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[Scatmancraig]

My 2.5 TD Omega has a slight cooling issue.

Up till now, it has been fine in normal driving. Temp gauge goes up to about 95, at which point the thermostat appears to kick in and it settles back down to approx 92, and stays there. The viscous fan kicks in at just over 90, which seems to low to me, but this is a separate issue.....

The problem is, when you drive the car a little more "enthusiastically", the temp gauge rises quite quickly to around 100. It may even go higher than that, but I didn't risk pushing the car any further. It comes back down fairly quickly afterwards, which is reassuring.

Last weekend I had a look under the bonnet. The radiator seemed to be fairly caked up externally with black gunge from a previous oil leak. So I removed it from the car and took it for a blast through a high pressure jet wash. I also ran a hose through it and made sure that there was no dirty water blocking things up internally.

The car still gets hot quickly when pushed. It's still perfectly fine under 'normal' driving. Both electric fans work as they should. It doesn't loose any coolant anywhere, so there clearly isn't a leak. I ran a hose through the rest of the system today to give it a decent flush out, so it's currently running on straight water. The water pump is pumping as I disconnected various hoses and left the engine running, and it was coming out at a fair rate. Got some anti-freeze waiting for me to collect tomorrow, so that'll be going in asap.

Any ideas why it might get so hot so quickly when pushed, but runs perfectly fine the rest of the time?  The last TD I owned also seemed to get hot when pushed, is it a characteristic of these engines?  I've no idea what normal running temp is on a TD, so I may not have an issue at all, but i'd be interested to hear others thoughts!

[Shackeng]

I found mine was the same until I gave the radiator a proper clean out. It now runs happily without the viscous fitted, & never gets above 95.

[Scatmancraig]

I found mine was the same until I gave the radiator a proper clean out. It now runs happily without the viscous fitted, & never gets above 95.

I might take mine off again and give it another go with the hosepipe.  It's a bit confusing as it has four hoses connected to it.  Two big ones that appear to be connected to the engine, and two smaller ones that seem to be attached to a small auxiliary electric pump mounted on the drivers side inner wing.  I've no idea of the best method of removing any internal crud.  No matter which way I connected the hosepipe to it earlier, all I got was clean water out. 

I took the viscous off mine last weekend.  It ran a little hot and even a normal journey got the electric fans on at low speed.  So I refitted the viscous.  Because I removed the bi-metallic strip thinking it was the same as a Senator (their viscous units are bolted from the front), I managed to bend the strip, now my viscous fan is on permanently!  No bad thing I suppose, apart from the excessive whooshing noises and detrimental effect on fuel consumption.

I'm collecting some anti-freeze tomorrow, it might help a bit.  Although I'm reluctant to put it in until I'm happy with the rest of the system.  I've got to do a transmission fluid change soon, so I'll probably remove the rad and blow the last of the old fluid out of the oil cooler part, then refit it all with the fresh anti-freeze in.  I've also got my eye on a new viscous coupling, so then I'll know if my old one was faulty as it used to come on at just above 90 degrees, which I always felt was too soon.

[TheBoy]

TD rads start to sludge up around 120k, esp with poor servicing.

Oilways, particularly the piston jets, sludge up with poor servicing.


Both can cause issues you've had, both *WILL* destroy head and/or HG if you hit 100C on gauge (110C in reality)

[Scatmancraig]

TD rads start to sludge up around 120k, esp with poor servicing.

Oilways, particularly the piston jets, sludge up with poor servicing.


Both can cause issues you've had, both *WILL* destroy head and/or HG if you hit 100C on gauge (110C in reality)

Well today I took it on a 40 mile journey to Cleethorpes.  25 degrees outside, and 4 people in the car.  There's a few long hills, 2nd or 3rd gear with foot hard down (auto box), and it peaked at 95 degrees on the gauge.  So it's not at critical just yet, and normal running it is fine, its only when driven hard when it gets hot.

Is it worth running some flushing oil through the engine before I change the oil next weekend?  I'd heard some horror stories about using it in engines as it can cause more problems than it solves.  The radiator is running nice and clean now, although it still has straight water in it and no anti-freeze at all.  Picked some up today so that'll be going in shortly after the oil change.  Is there any kind of cooling system flush product available, as I could run that through just to be totally sure.

[TheBoy]

Never run neat water in the coolant system, even this time of year, it will opps it.

If its history does suggest poor servicing (ie, longer intervals than the specified 4,500 mile oil change), put a very strong oil flush through it (not the type you leave in for a few miles, the sort you idle for 15mins).

Now you've shagged the coolant system as well, that probably needs a decent flush through - not the Holts shite Halfords sell.

[Scatmancraig]

Never run neat water in the coolant system, even this time of year, it will opps it.

If its history does suggest poor servicing (ie, longer intervals than the specified 4,500 mile oil change), put a very strong oil flush through it (not the type you leave in for a few miles, the sort you idle for 15mins).

Now you've shagged the coolant system as well, that probably needs a decent flush through - not the Holts shite Halfords sell.

Opps?  I'm not with you??

Any recommendations for a decent coolant flushing product?  Never used it before.  Do you add it in then drive the car for a while? 

The straight water has been in since yesterday afternoon, done approx. 80 miles since. I have 5 litres of GM red anti-freeze now, not sure what the cooling system capacity is on the TD nor what ratio of anti-freeze to water to add.

[Diamond Black Geezer]

For winter use 50-50, you can drop to 25-75 (or even less) for summer, but I run on 50-50 because it 'can't hurt' sort of thing. Also antifreeze has anti-corrosion properties, don't forget. From memory about ten litres in total went in, might be a bit under.   

[Scatmancraig]

For winter use 50-50, you can drop to 25-75 (or even less) for summer, but I run on 50-50 because it 'can't hurt' sort of thing. Also antifreeze has anti-corrosion properties, don't forget. From memory about ten litres in total went in, might be a bit under.   

Nice one.  I'm going to collect some coolant flushing product on my way home tonight and run it through the system.  Not sure what the procedure is, I guess it depends on which product I use.  I have a friendly motor factors that should be able to advise something suitable.  That anti-freeze you got me is 5 litres, so in theory I'll be pretty much using all of it, plus the same quantity of straight water to completely fill the system. 

Hopefully, this will improve things on the cooling front, if not I guess either my water pump is shagged or part of the system is badly blocked.  The water in the header tank is still clear, so I don't think there's a huge amount of crap still in there thats going to come out, but then I don't know how powerful the coolant flush is so I might be surprised.

[Shackeng]

Best to use filtered rain water if possible. Our water is heavily limed.

[Diamond Black Geezer]

Let us know how you get on with the coolant flush.. at present I've got my eye on my special product which is 79p/litre from Asda 

[Scatmancraig]

Let us know how you get on with the coolant flush.. at present I've got my eye on my special product which is 79p/litre from Asda 

Well, things are improving slightly.

Bought some coolant flush from my friendly local motor factors.  No time like the present, so I got home and cracked on.  Added the coolant flush, which conveniently says on the label that its better to use this in straight water, and left it running for the required amount of time.

Couldn't get enough of a grip on the drain plug in the radiator, so removed the small radiator hose that's next to it and dropped the contents of the radiator.  Flushed the system with more water, and tried to get as much out as I could be disconnecting various hoses and blowing through them. 

Mixed up some anti-freeze 50/50 and added it back in.  Had my tea, then went for a drive.  Viscous fan was howling away as usual, as it was when I arrived home a few hours earlier.  But as if by magic it stopped howling all by itself!  My return journey back home a couple of hours later was promising as well, as the viscous fan didn't cut in at all.  I thought that this must be a fluke, but the journey to work this morning was the same, normally the viscous fan used to kick in approx 3/4 of the way, I even deliberately went a very long way round and still no viscous fan.

Now all of this means that a) the viscous fan has decided to freewheel permanently, or b) the coolant flush and fresh anti-freeze has made enough of a difference to keep the engine cool enough to stop the viscous fan from reaching its locking point.  Confusingly, the temp gauge still reads exactly the same as it did before (sits at just over 90 normal running), and I haven't tried pushing the car harder yet to see if the gauge still gets hotter more quickly.  But I'd certainly say its a step in the right direction! 

[Diamond Black Geezer]

I've gone and asked a question you've already answered in another thread, re: the drain plug/hose - I'd say right choice pulling the hose off. So what was this wonder product? 

[Kevin Wood]

Temperature gauges often lie about what's really going on. Specifically, they have a dead point around normal operating temperature so the needle doesn't move too much with the normal fluctuations of temperature and panic the driver.

No experience of the TD's gauge, but bear that in mind.

Sounds like you've made an improvement. If the viscous fan gets annoying, bear in mind that many TD drivers report that it works perfectly well with just the electric fan. Store the viscous fan vertical if you do decide to remove it.

[Diamond Black Geezer]

Same with me, I reckon a new stat would help my engine, but there's nothing apparently wrong on the temp gauge... pinch of salt, really, I think. I does sound like Mr Scatman has done good. 

[Scatmancraig]

Temperature gauges often lie about what's really going on. Specifically, they have a dead point around normal operating temperature so the needle doesn't move too much with the normal fluctuations of temperature and panic the driver.

No experience of the TD's gauge, but bear that in mind.

Sounds like you've made an improvement. If the viscous fan gets annoying, bear in mind that many TD drivers report that it works perfectly well with just the electric fan. Store the viscous fan vertical if you do decide to remove it.

I removed the old fan previously, and the engine got a little too hot for comfort, to the point where the electric fans were coming on at low speed after a short but spirited drive.  It was at this point I broke the original viscous as I removed the bi-metallic strip in the centre.  I thought it would be like a Senator/Carlton unit where the fan assembly is held to the shaft by an allen headed bolt under the strip.  I refitted it, but the viscous fan was then on all the time as I'd bent the strip to the point where the little button under it wasn't pressed in at all.  I still refitted it as it was though, better to have the fan on all the time than not at all.

The replacement fan, a second hand unit off Diamond Black Geezer, was initially working in exactly the same way as the one that came off (before I broke it), i.e. it would be silent until you'd driven the car for about 4 miles, then it would kick in.  Definitely not the case now, thankfully.

Same with me, I reckon a new stat would help my engine, but there's nothing apparently wrong on the temp gauge... pinch of salt, really, I think. I does sound like Mr Scatman has done good. 

I can't remember the name of the product I used, other than it wasn't the Holts stuff I'd been advised not to use.  The instructions said to add it to the header tank and leave the engine ticking over for 15 minutes.  I wasn't holding out any hopes, and the liquid I drained was brownish, but no sludge to speak of.  But as the cooling system was 100% water for the past week, it maybe has dislodged a bit of crud, and the added bonus of having proper new coolant in the system would also help. 

To drain the system, I removed the smaller bottom hose that sits next to the drain plug on the passenger side of the rad.  God knows how you're meant to get the drain plug open from the position its set in, there isn't enough room to grip it to turn, or get a screwdriver in the slot!  Don't forget that I previously removed the radiator from the car and took it to the local jet wash to clean it externally, I also turned it both ways up and ran a hose through it, plenty of brown shite came out then, so I guess most of the remaining crud was hiding in the rest of the cooling system.  I also flushed the system out with a hosepipe last Saturday, so from then till last night it had clear water in it.

Once I've changed the oil, I'll give it a good blast up the bypass and see if it starts to get hot again.  The viscous fan can remain on for the time being, I main even drain the coolant again in a few weeks just to be sure.

[Diamond Black Geezer]

Happy days. Glad that fan is a good 'un, anyway 

[Diamond Black Geezer]

Just looking at the Howto re: flushing out the coolant/HBV/heater matrix etc... and it mentions that you can't 'fully flush out' the system without removing the water pump...that's interesting. How did you remove all traces of the cleaning agent, was it literally sitting there with a gardenhose in the top, and the hose off at the rad, sort of thing? Ta 

[Scatmancraig]

Well I thought it was too good to be true.   This viscous fan kicked in again on my journey home from work, during normal stop start driving.  A short burst of foot to the floor driving also saw the gauge climb quickly, although only up to an 'indicated' 95, by then I was fast approaching a 30 milit so had to back off sharpish!

I was going to change the oil anyway today, so got that out of the way when I got home, can't do any harm if it doesn't do any good.  Noticed that the centre of the radiator (the bit directly in front of the fan) is cold, but the viscous fan still remains locked in.  Both edges of the radiator are quite warm though, is this normal?  Or have I got some sort of restriction in flow around the coolant circuit.

I'm reluctant to believe that the water pump has failed completely, as surely if it had, the car would boil up quite easily, which it doesn't.  There's barely any pressure at all in the header tank if you release the cap just after switching the engine off.  You can drive it all day as it is, and providing you don't thrash it, the temperature remains what I consider to be normal at just over 90.  Even in traffic it never goes higher than 95, and soon goes back to normal when moving again.  Is it possible for the pump to get less efficient over time?  Or is there an issue with the thermostat?  I guess a sticking thermostat would cause the engine to get excessively hot and not allow water to pass through the radiator, so maybe its worth taking it off to see.  Is there any way of testing the water pump without removing it?

What exactly activates the viscous fan?  Is it the heat from the engine passing through the metal shaft and releasing the switch, or hot air passing through the radiator?  And where is the thermostat on these engines?  Is it under the cover on the front of the block, just to the left hand side a little?

Any further advice would be much appreciated!

[Nick W]

That still sounds like a coolant flow issue to me.


Your short lived improvement from flushing the radiator suggests that you were on the right track, and once again proves that chemical coolant flushes aren't particularly effective. A new radiator would be the cure if you were certain it is the fault, but unfortunately isn't something you can easily check.


A failing waterpump due to a loose or damaged impeller is easy to check, common and cheap to fix. I would remove it just to be certain.


Finally viscous fans: my understanding is that they only turn at low RPM and have little to do with temperature sensing. This explains why you can normally hear a faulty fan coupling from the racket it makes over the 2500(ish) RPM it isn't designed to work at. A new coupling is also cheap, and new BMW waterpumps won't be warranted without a new one.

[Scatmancraig]

That still sounds like a coolant flow issue to me.


Your short lived improvement from flushing the radiator suggests that you were on the right track, and once again proves that chemical coolant flushes aren't particularly effective. A new radiator would be the cure if you were certain it is the fault, but unfortunately isn't something you can easily check.


A failing waterpump due to a loose or damaged impeller is easy to check, common and cheap to fix. I would remove it just to be certain.


Finally viscous fans: my understanding is that they only turn at low RPM and have little to do with temperature sensing. This explains why you can normally hear a faulty fan coupling from the racket it makes over the 2500(ish) RPM it isn't designed to work at. A new coupling is also cheap, and new BMW waterpumps won't be warranted without a new one.

Yes it definitely seems to be a flow issue like you say.  I have removed the radiator once before, and plenty seemed to be coming out of either end when you ran water through it.

With regards to the viscous fan, there's a bi-metallic strip across the front of them, which keeps a small plunger depressed.  When the metal strip heats up, it bends slightly, thus allowing the plunger to rise, then locking the fan on.  My old fan worked exactly the same as my current fan, until I removed it and accidentally bent the strip so that the plunger was out all of the time.  hen I refitted the fan, it was locked in all the time. 

Is the waterpump easy to remove on the TD engine?  I have no Haynes manual as guidance.  Well actually I do, but only for petrol Omegas.  Just had a quick look for water pumps and they do seem cheap enough.  I wonder if they are Omega specific, or will one from a BMW 325 or 525tds be identical (loads more to choose from then!). 

[Nick W]

The pump seems to be pretty much the same(it may even be the same) as BMW petrol sixes. In which case, you remove the fan coupling, undo 4 bolts, and knock it off with a mallet. The mallet is quicker and easier than using the provided tapped holes to draw it off.

[Scatmancraig]

The pump seems to be pretty much the same(it may even be the same) as BMW petrol sixes. In which case, you remove the fan coupling, undo 4 bolts, and knock it off with a mallet. The mallet is quicker and easier than using the provided tapped holes to draw it off.

I've just read an article on a BMW forum about it.  Looks an easy enough job.  Water pump prices aren't bad either, although I guess that ones with metal impellors are better.  I'm guessing my issue is either a failed or partly failed water pump, or a partly blocked radiator.  Water definitely passes through the radiator, I can blow through the system from one side to the other, and plenty comes out the opposite side.

[Nick W]

The pump seems to be pretty much the same(it may even be the same) as BMW petrol sixes. In which case, you remove the fan coupling, undo 4 bolts, and knock it off with a mallet. The mallet is quicker and easier than using the provided tapped holes to draw it off.

I've just read an article on a BMW forum about it.  Looks an easy enough job.  Water pump prices aren't bad either, although I guess that ones with metal impellors are better.  I'm guessing my issue is either a failed or partly failed water pump, or a partly blocked radiator.  Water definitely passes through the radiator, I can blow through the system from one side to the other, and plenty comes out the opposite side.

The only problem is that doesn't prove that the water is flowing through the radiator in a manner that will cool it. it can still be badly silted up.

[Scatmancraig]

The only problem is that doesn't prove that the water is flowing through the radiator in a manner that will cool it. it can still be badly silted up.

I agree.  I'm not 100% sure which direction the water is supposed to flow in either.  Water would appear to come through the big top hose on the passenger side, and out of the big bottom hose on the drivers side.  But then there's the two smaller hoses, that are attached to what appears to be an electric auxilliary pump, the top one being on the drivers side, the bottom on on the passenger side.

The viscous stayed silent again this morning, so at least there's been some sort of an improvement over previously.  I need to go on a slightly longer journey from cold to see exactly how long it does take for it to cut in now.  The journey home last night was interrupted by a short stop to collect my oil filter.  It was after this stop when the viscous kicked in. 

What purpose does the auxilliary electric pump serve, and would it affect things in any way if it wasn't working?

[Scatmancraig]

On a related matter, what is the purpose of what appears to be an electric auxiliary water pump mounted on the drivers side inner wing, alongside the fuel filter?  It is connected to two smaller diameter hoses, one of which goes to the top of the radiator on the drivers side, the other appears to be connected to the small lower hose on the nearside of the rad, just above the drain valve.  I've never had a car with this type of device fitted, I was wondering exactly what purpose it serves, and whether if it had failed, would it have any effect on the problems I'm having?

I've ordered a new main water pump anyway, it was cheap enough.  No idea if it has a plastic impellor or not, but even a new one with plastic impellor ought to be better than one that has failed.  When it arrives, I'll take the rad off once more and try and flush it again to see if any more brown crud comes out like it did the first time. 

[TheBoy]

you can drop to 25-75 (or even less) for summer

No, no, no, no, no. NO.

No.

No.

NO.


In case that was unclear, NO.

[Doctor Gollum]

1. Does it have aircon?

If no, move to last question.

2. Does the front fans work?

If no, find out why. If yes, go to next question.

3. Does the compressor work as expected?

If yes, skip to last question.

4. Is the aircon gassed, or has it recently been done?

If yes, skip a question.

5. Get it regassed.
 
6. Does it now all work as it should?

If yes, go to last question.

7. Does the condensor leak?

If yes, order one when you order your radiator.

8. Have you fitted your new radiator yet?

  

[Doctor Gollum]

Whilst my last post may seem flippant, it does raise a genuine point...

If your aircon, assuming fitted, doesn't work, then the lack of additional cooling effect from the extra fan or two may well be limiting the effectiveness of the radiator, even more so if auto with a separate cooler.

Leaving the working aircon in Eco mode has the same effect as it not working... ie the auxiliary fans will be off.

If you don't care about aircon, then remove the condenser keeping the front fans and fit an inline switch to the fan circuit in lieu of the aircon ecu input.

A new radiator is easy enough to fit, but to change the condenser requires radiator removal, hence the question

[Scatmancraig]

Whilst my last post may seem flippant, it does raise a genuine point...

If your aircon, assuming fitted, doesn't work, then the lack of additional cooling effect from the extra fan or two may well be limiting the effectiveness of the radiator, even more so if auto with a separate cooler.

Leaving the working aircon in Eco mode has the same effect as it not working... ie the auxiliary fans will be off.

If you don't care about aircon, then remove the condenser keeping the front fans and fit an inline switch to the fan circuit in lieu of the aircon ecu input.

A new radiator is easy enough to fit, but to change the condenser requires radiator removal, hence the question

It is auto, and it does have aircon, but there's no gas at all in the system.

I have tested the twin fans, both work at low and high speeds.  I did remove the viscous altogether for about a day, but this resulted in the electric fans coming on at low speed after a relatively short drive.  I wasn't happy with this as I felt they shouldn't have come on at all, but at least it proved that they do work.  I refitted the viscous, which by this time had decided to lock up permanently as i'd managed to damage the bi-metallic strip that activates it.  This has since been replaced with one that works properly.

The other day I opened the bonnet after getting home from work (viscous had already locked up).  The temp gauge was reading 92.5.  The centre of the radiator, i.e. the bit directly behind the fan, was stone cold.  The edges of the radiator were quite warm, particularly the passenger side end that has the larger hose at the top.  So either the radiator is blocked, the thermostat is stuck, or the water pump isn't pumping.   

I've already had the radiator out a couple of weeks ago, lots of brown water came out.  But it seemed to flow from one end to the other ok when I ran a hose through it. 

A water pump is on order, should be here today or tomorrow.  It may not need replacing, but I'm doing it for peace of mind and to eliminate it as the cause of the problem.

Where does the auxiliary electric pump come into the equation?  I've still no idea of its purpose!

Another question....  Is the radiator on the TD unique to that engine or the same as the petrol versions?  Mine has the integral oil cooler for the transmission, and connections for smaller hoses for the auxiliary pump.  Having never had a petrol Omega, I'm not sure of the set up.

[Doctor Gollum]

Which aux pump? The one under the expansion tank, or the one on the radiator?

The one under the expansion tank is for cabin heat with engine off, and therefore largely irrelevant.

The one on the radiator is for helping coolant flow across the radiator, this might not be working...

If you have both, simply swap them over as they are identical

[Kevin Wood]

The radiator electric pump only runs after shutdown on the v6. Can't remember if it's different on the td. It's just there to prevent after boiling.

[Scatmancraig]

Which aux pump? The one under the expansion tank, or the one on the radiator?

The one under the expansion tank is for cabin heat with engine off, and therefore largely irrelevant.

The one on the radiator is for helping coolant flow across the radiator, this might not be working...

If you have both, simply swap them over as they are identical

The I was referring to is the one under the expansion tank. 

I've not seen one on the radiator itself, so I assume I haven't got one.  At least I know that it can be discounted from investigations!

Just need the water pump to arrive now.  Will remove the rad and have another go at cleaning it.  It probably is the cause, but it's a damn sight more expensive than a pump, unless there's a decent secondhand one about, hence needing to know if one off an auto V6 would fit?

[TheBoy]

Check all the "Project TB2" threads.

But to summarise:

Cooling issues with TD
Waterpump shed is vanes (instant overheat)
Rad silted (overheats on long periods of heavy throttle)
Cylinder jets blocked (overheats on long periods of heavy throttle)

Side effects:
If you hit 100C on gauge (which is 110C in reality), you have probably damaged the head and or the HG



You can bugger around with fans and other shit for months, and spend a fortune trying to avoid the 2 slow overheating issues above, but eventually you'll have to accept those.  Hopefully before you've done further damage.

[TheBoy]

And, shit, that forum saga has left me far too familiar with the tractor lump 

[Scatmancraig]

Check all the "Project TB2" threads.

But to summarise:

Cooling issues with TD
Waterpump shed is vanes (instant overheat)
Rad silted (overheats on long periods of heavy throttle)
Cylinder jets blocked (overheats on long periods of heavy throttle)

Side effects:
If you hit 100C on gauge (which is 110C in reality), you have probably damaged the head and or the HG



You can bugger around with fans and other shit for months, and spend a fortune trying to avoid the 2 slow overheating issues above, but eventually you'll have to accept those.  Hopefully before you've done further damage.

I'm guessing that the rad is blocked, or at least partially blocked.  I checked it earlier as I pulled up within seconds of the viscous fan kicking in, the centre of the rad was hot, so at least some water is passing through it.  Checking it after a few minutes of the viscous howling reveals a rad with stone cold centre and hot edges. 

I've only had it up to 100 on the gauge once, very briefly.  If it has buggered the HG or head then so be it, it'll have to take its chances until it finally fails.  I'm changing the water pump when it arrives, and having another go at cleaning the rad (internally).  Cheapest replacement rad I've seen is just shy of £100, and I haven't got that spare for a couple of months at least.  With the car only costing me £250 in the first place, I'll take my chances.  Unless anyone has a cheap second hand rad I can take off their hands?

If the oil jets are blocked then I'm not really sure what I can do.  I changed the oil earlier this week, used some additive to flush the old oil before dropping it all and replacing with GM's finest 10w40 semi-synthetic.  The car has history up to 140k (it's on 164k now), and I know the oil was changed at least 12 months ago as by coincidence I got my oil filter from the same place a previous owner bought theirs from, the registration was still on their records.  As I have enough oil in stock for another couple of changes, I may drop the oil again soon, just to be doubly sure.

I'm not going to give up on this car just yet!  I've 24 years history of running banger money cars on a shoestring budget, and I haven't too many total failures to my name.  It still drives spot on, noisy fan excluded, and its such a comfy old barge. 

[Scatmancraig]

Water pump arrived today, so I've removed the old one tonight.  I doubt if the water pump was at fault as it is a metal impellor one and seemed to be intact.  I've removed the radiator, drained the coolant (which was still the correct colour so at least there's not too much crap floating around the system).  The radiator is now laid flat on the garage floor and I've filled it with a rather unconventional liquid known for its cleaning powers to try and see if it shifts anything.  I'm clutching at straws a bit as I doubt if it will work, but I've had good results with it in other applications.

I'm wondering if something like a dishwasher cleaner or drain unblocking liquid left in the radiator would shift any crap that has built up?  Has anyone tried anything like this before?

[Nick W]

I'm wondering if something like a dishwasher cleaner or drain unblocking liquid left in the radiator would shift any crap that has built up?  Has anyone tried anything like this before?

You are going to really struggle to get enough of the cleaner into enough of the radiator to achieve anything useful. Let alone get all of the resulting mix out of the radiator. Even brass radiators were cleaned by mechanical means(they unsoldered the tanks, and poked rods through the passages) not chemical ones. Aluminium radiators are a typical modern product; they have production advantages, but are not expected to be maintained or serviced, just replaced. And is the £100 you mentioned really a lot to fix the problem?

[Scatmancraig]

I'm wondering if something like a dishwasher cleaner or drain unblocking liquid left in the radiator would shift any crap that has built up?  Has anyone tried anything like this before?

You are going to really struggle to get enough of the cleaner into enough of the radiator to achieve anything useful. Let alone get all of the resulting mix out of the radiator. Even brass radiators were cleaned by mechanical means(they unsoldered the tanks, and poked rods through the passages) not chemical ones. Aluminium radiators are a typical modern product; they have production advantages, but are not expected to be maintained or serviced, just replaced. And is the £100 you mentioned really a lot to fix the problem?

You have a valid point. A new radiator would be ideal.  It will probably happen eventually.  After nearly 25 years of messing about with cheap cars, I've never had one with this issue so I'm still learning!

[Scatmancraig]

Well I'm almost certain now that it's my radiator that is at fault. Well that or there's another more worrying problem.

The car has a new water pump now, and it's still just the same. I've tried 3 different products on the cooling system, no difference.

Is the TD radiator any different to those in the petrol cars? Or were all automatic Omegas with air-con fitted with the same radiator? Just makes my search slightly easier.

[Seth]

The rad is 'TD specific'

I experienced the exact same problem on a previous TD; and fitted a brand new rad.
That helped ... though the gradual increase in engine temp re-occurred when towing the caravan up long inclines.

I'm now convinced that it was a damaged cylinder head/blocked piston oil jets that was my problem.
Our present TD runs constantly (and correctly) at the mid-point on the gauge.

And a 50% antifreeze mixture is critical at all times. Good luck anyway! 

[Scatmancraig]

The rad is 'TD specific'

I experienced the exact same problem on a previous TD; and fitted a brand new rad.
That helped ... though the gradual increase in engine temp re-occurred when towing the caravan up long inclines.

I'm now convinced that it was a damaged cylinder head/blocked piston oil jets that was my problem.
Our present TD runs constantly (and correctly) at the mid-point on the gauge.

And a 50% antifreeze mixture is critical at all times. Good luck anyway!

Well it's not much different from before to be honest, marginally better but not much. Just weighing up whether to bite the bullet and get a new rad, have seen new aftermarket ones for less than 100 quid delivered, which doesn't seem too bad.  The car is very solid underneath and ought to be ok for another mot when it is due in January, so providing nothing else expires, i reckon it'll be worth it.

When I do change the rad, I'm going to change the gearbox fluid and filter as well, as already got the parts and fluid ready to go.  Plus I'll give the engine oil another flush and change, as got enough oil for another couple of changes. 

[Scatmancraig]

Well I've bitten the bullet and ordered a new radiator.  Will hopefully be here tomorrow so it'll get fitted on Sunday.

Here's the link....

http://www.fastrads.co.uk/partfinder/?id=1&manuid=92&manu=Vauxhall&model=Omega&transmission=Automatic&year=1996&doors=5&trim=CDX&ModelType=Estate&engine=2.5&varient=2.5%20TD%20CDX%205d%20Auto

If this doesn't cure the problem, then I'm guessing my piston cooling jets are blocked or I have head problems.  The latter I doubt as no other issues like oil in the coolant or excessive pressure in the cooling system.  Blocked piston jets more likely as its on 164k now, albeit with reasonable history.

[Diamond Black Geezer]

Was the 'unconventional cleaning agent' what I think it is, Craig? How long was it in for, if it was what we were discussing?

[Scatmancraig]

Was the 'unconventional cleaning agent' what I think it is, Craig? How long was it in for, if it was what we were discussing?

Approx 2 litres of full-fat Coke!  I used it ones to clear the limescale from a particularly disgusting toilet bowl at a place I moved into a few years back.  It worked a treat in the toilet, not so well on my radiator.  I also used some heavy duty kettle descaler afterwards. 

I'm hoping that the new radiator will fix it for good.  Going to change the oil again, and run more oil flush through the system, to give it every possible chance to sort itself out.  May also get a new thermostat too.  With new coolant, new water pump, thermostat and radiator, you'd have thought that I'll never have to hear the noise of the viscous fan ever again!!

[Scatmancraig]

Yesterday I changed the radiator and thermostat, plus gave it another oil and filter change, and if anything it's now reading higher on the gauge than before.  I also changed the transmission oil and filter, that was fun!!

The new radiator does seem to be a lot thinner than the old one, it was advertised for my spec car (i.e. 2.5 TD Auto with air-con), so not sure if that's going to be why it is hotter. It doesnt boil over or pressurise, but that viscous still cuts in eventually. The replacement Thermostat looked slightly different to the old one too, its fits, but I swear that it doesnt open until the engine is hotter.

For now I'm going to have to live with it as it is, as I can't really see what else I can actually do!  Normal driving it seems happy enough, if you can put up with the fan howling most of the time.  I have a 200 mile round trip to do in it this week, so it'll be interesting to see how it behaves on the motorway.

[Shackeng]

I forget, have you already replaced the plastic pump with one with a metal impeller? If not, consider doing so ASAP, as they are a known failure item on these.

[Scatmancraig]

I forget, have you already replaced the plastic pump with one with a metal impeller? If not, consider doing so ASAP, as they are a known failure item on these.

I replaced the pump a couple of weeks ago, both the original pump and its replacement have metal impellors.

[Scatmancraig]

Maybe I was a little hasty in knocking the car down.  On the journey to work this morning, the viscous fan didn't cut in at all, despite going a longer way around and giving it a huge bootful of throttle when an arsehole in a chavmobile decided to try and overtake me up the inside (he lost!). 

What is weird is that the gauge seems to be reading slightly higher, but the fan doesn't come on?  I need to find a thermometer and check the real temp of the water, I've had an issue last week when I ran out of diesel with the gauge still showing that I had fuel, so it wouldn't surprise me if the temp gague was over reading as the car doesn't show any other physical signs of running too hot now.

[Kevin Wood]

You'll probably find the old thermostat was a bit lazy and opening early. If it's not rising on "spirited" bits of driving any m,ore, it does sound like you've improved it. My guess is that the radiator was past its' best.

[Scatmancraig]

You'll probably find the old thermostat was a bit lazy and opening early. If it's not rising on "spirited" bits of driving any m,ore, it does sound like you've improved it. My guess is that the radiator was past its' best.

I was thinking along those lines. It just worries me that the replacement rad is a lot thinner, than the original one.

[Diamond Black Geezer]

Don't let it, man. I'd say keep your eye out for a nice nick 2nd hand unit, and also for and original GM on NOS on ebay and the like. And factor in how long that rad will last, vs the proce of a GM one (did you ring Vauxhall and see how much they wanted?) don't lose sleep over it 

[Omegatoy]

sludge pump! "shudders"
thing your missing Craig, is when you give it a bootful, not only is the engine producing a lot of heat but so is the autobox, which has its cooler mounted in front of the main rad, ergo you now have two sources of heat so the temp rises slightly while booting it,its pretty normal behaviour on a sludgepump td,with a tired autobox as long as it comes back down while cruising after booting it, wouldnt worry to much,except autoboxes on the td are not ong lasting really and the extra heat is a sign of it being a little worn,the fluif flush on the box plus filter should have helped slightly which if im reading it right it did on the trip to work afterwards,ar35 change to it!

[Shackeng]

sludge pump! "shudders"
thing your missing Craig, is when you give it a bootful, not only is the engine producing a lot of heat but so is the autobox, which has its cooler mounted in front of the main rad, ergo you now have two sources of heat so the temp rises slightly while booting it,its pretty normal behaviour on a sludgepump td,with a tired autobox as long as it comes back down while cruising after booting it, wouldnt worry to much,except autoboxes on the td are not ong lasting really and the extra heat is a sign of it being a little worn,the fluif flush on the box plus filter should have helped slightly which if im reading it right it did on the trip to work afterwards,ar35 change to it!

Not now!

[Scatmancraig]

sludge pump! "shudders"
thing your missing Craig, is when you give it a bootful, not only is the engine producing a lot of heat but so is the autobox, which has its cooler mounted in front of the main rad, ergo you now have two sources of heat so the temp rises slightly while booting it,its pretty normal behaviour on a sludgepump td,with a tired autobox as long as it comes back down while cruising after booting it, wouldnt worry to much,except autoboxes on the td are not ong lasting really and the extra heat is a sign of it being a little worn,the fluif flush on the box plus filter should have helped slightly which if im reading it right it did on the trip to work afterwards,ar35 change to it!

The autobox cooler is inside this radiator!

My journey home was encouraging, viscous fan stayed off for longer than normal. Temp raised a little after I got up to 70 on the bypass, then there was heavy traffic at crawling speed for the next mile or so, which is when the viscous cut in. When I turned off the bypass, the fan cut out again in less than a mile. That's never happened on the journey home before, the fan normally stayed on till I goy home.  So that proves to me that the coolant is circulating better than it was. Plus you have to factor in that it was 25 degrees out there.

I'm off to Walsall on Friday, 100 miles from here and mostly  on dual carriageway. So if the fan stays off for that journey, I'll know that things are better.

The autobox is definitely tired on this car, the old fluid wasn't a great colour. There wasn't any broken bits in the sumps, and the magnet was nice and clean. The only real symptom that it's not the best is that it's a little slow to engage reverse. Takes up forward drive quickly enough though, so it can stay where it us until it breaks!  I just need to sort the larger sump out as a previous owner had put a load of chemical metal over the filler plug, which itself was rounded off. It was also slightly bent around that corner. Consequently it now leaks a couple of dribbles when parked. I wouldn't be too bothered if it had a normal filler tube, but it's such a pain to top up!!

[TheBoy]

Is it still getting hot on long periods of heavy booting? If not, . If so, strong oil flush I'm afraid...

[Scatmancraig]

Is it still getting hot on long periods of heavy booting? If not, . If so, strong oil flush I'm afraid...

A little, but not as bad. I've flushed engine oil twice and replaced filter and oil with new, first time a couple if weeks ago and again when I did the radiator and transmission fluid. 

What's the best engine flush to use?

[TheBoy]

Hopefully Omegatoy can remember the bloody paint-stripper one he got for my TD....

...not a brand I'd heard of.

[Doctor Gollum]

sludge pump! "shudders"
thing your missing Craig, is when you give it a bootful, not only is the engine producing a lot of heat but so is the autobox, which has its cooler mounted in front of the main rad, ergo you now have two sources of heat so the temp rises slightly while booting it,its pretty normal behaviour on a sludgepump td,with a tired autobox as long as it comes back down while cruising after booting it, wouldnt worry to much,except autoboxes on the td are not ong lasting really and the extra heat is a sign of it being a little worn,the fluif flush on the box plus filter should have helped slightly which if im reading it right it did on the trip to work afterwards,ar35 change to it!

Not now!

You question the radiator thickness, yet don't retain the separate oil cooler... the mind boggles

[Shackeng]

I may have misremembered this, but when I replaced my TD rad with an aftermarket one, I had to use the built in oil cooler for the gearbox. Why I wasn't able to use the separate one I can't remember.

[Scatmancraig]

My car doesn't have a seperate transmission oil cooler, both the old and new radiators have it built into the drivers side of the radiator.  I wasn't even aware Omega's had a seperate cooler, I know older Senators and Carlrons did, but I think even they went for the integral cooler on later cars.

[Scatmancraig]

Well today I took the car on a near 200 mile round trip to help my daughter move house. Viscous remained silent for 95% of the time, it only really came on after idling in heavy traffic for a while, and soon went off again once moving.  And bear in mind as well tha I had two passengers and a very full boot for 50% of tbe time, plus it was over 20 degrees outside.

In other words, it's a hell of an improvement on how it was before!  Still not perfect as it still warms up quickly under full throttle, but cools down again soon after. And it will happily sit at 80+ without getting hot too.  I think as long as I don't take it racing then I can probably trust it a bit more now!!

[Diamond Black Geezer]

Good news 

[Scatmancraig]

Good news 

Indeed.  And it continues to behave, viscous hardly cuts in at all since the weather has cooled down a bit as well.

Still got to do that bloody belt tensioner though.  I know its only a 10 minute job to change it, I'm just tight and I don't want to spend any more on it just yet!!

[Diamond Black Geezer]

You might be tight, but the tensioner certainly isn't! 

[TheBoy]

Remove the viscous, it helps keep the I/C fan in functioning condition.

[Diamond Black Geezer]

The Turbo Weasel ran without a fan for almost its entire time in our family... in fact I think that's actually the one you now have! 

[Scatmancraig]

Remove the viscous, it helps keep the I/C fan in functioning condition.

I may try it again without the fan once I've sorted the tensioner.  The viscous hardly ever comes on, so I know its cooling a lot better than it was.  I also know that the electric fans work as they came on before when I tried running it without the viscous for a very short while before I replace the water pump and radiator.

You might be tight, but the tensioner certainly isn't! 

Don't give up the day job.....! 

[Diamond Black Geezer]

Haha. Actually I am, sick of the ruddy place!