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[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!!