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[gbh]

Had this problem of slow water leak or top up after a long run.Its been going on a very long time and I've never managed to solve it.When I did the cam cover gaskets a couple of months ago I noticed some slightly pinky crunchy powder like stuff by the oil cooler so I was thinking maybe there?But when the engine was going and I was underneath I thought their maybe some water on the alternator.After said longish run or fully warmed up you do get that smell of warm water and sometimes a puff of steam but still I can't find it.Your thoughts would be appreciated Glenn

[tunnie]

First off check the HBV area is all dry 

[gbh]

I'll try and get my hands in there if possible! When I checked the other night the 2x1" hoses one i think goes to the HBV was very hot and pressured this maybe normal?

[05omegav6]

Could also be a pinhole in the rad or a pipe... needs pressure testing to be sure

[jimbo125]

Just to add to this thread, I own a 1998 2.5V6 CDX recently strong smell of coolant from under the bonnet did a long motorway run about 120 miles no loss of coolant but around town loose about 1/2 liter of coolant over a 2week period. No obvious leak checked under the car on numerous occasions after a trip nothing to be seen on the tarmac thinking slow HBV leak, any other ideas? Cheers

[05omegav6]

Just to add to this thread, I own a 1998 2.5V6 CDX recently strong smell of coolant from under the bonnet did a long motorway run about 120 miles no loss of coolant but around town loose about 1/2 liter of coolant over a 2week period. No obvious leak checked under the car on numerous occasions after a trip nothing to be seen on the tarmac thinking slow HBV leak, any other ideas? Cheers

More likely a radiator leak... hbv will leak all the time the engine is running

[gbh]

I checked the HBV without engine running and seems dry.But i'll have another check tomorrow with engine running mind you not much room to get your hand in.

[Andy B]

I checked the HBV without engine running and seems dry.But i'll have another check tomorrow with engine running mind you not much room to get your hand in.

You also need to cycle the heating hot/cold & with and with air con on too 

[jimbo125]

Just to add to this thread, I own a 1998 2.5V6 CDX recently strong smell of coolant from under the bonnet did a long motorway run about 120 miles no loss of coolant but around town loose about 1/2 liter of coolant over a 2week period. No obvious leak checked under the car on numerous occasions after a trip nothing to be seen on the tarmac thinking slow HBV leak, any other ideas? Cheers

More likely a radiator leak... hbv will leak all the time the engine is running

Thanks for the reply will check it out surprised I do not see a tell tale patch when parked. Cheers.

[Kevin Wood]

Just to add to this thread, I own a 1998 2.5V6 CDX recently strong smell of coolant from under the bonnet did a long motorway run about 120 miles no loss of coolant but around town loose about 1/2 liter of coolant over a 2week period. No obvious leak checked under the car on numerous occasions after a trip nothing to be seen on the tarmac thinking slow HBV leak, any other ideas? Cheers

More likely a radiator leak... hbv will leak all the time the engine is running

Thanks for the reply will check it out surprised I do not see a tell tale patch when parked. Cheers.

Park it on the lawn. The brown patch on the front lawn where mine overhangs led me straight to my last coolant leak - once I'd noticed it and put 2 and II together.

[gbh]

Went for a run today set temp to high,well the wife was happy as it did get quite warm.However the HBV seemed quite dry although its difficult to get your hand there and hot too.Will put up on ramps tomorrow and try again

[gbh]

I was thinking of getting some dye in the system that might be more spotable?

[Gaffers]

That pinkish residue is classic oil cooler plate leak.  It sits and gets hot so unless the leak is significant you don't get any runoff. And when you strip down it has all evaporated.   In the dark run your engine very warm and with about 2k revs shine a high power torch around the plenum area to see if you can see any vapour coming off, hopefully it's not oil from the rocker covers though

[Andy H]

The coolant transfer pipe is another possible culprit.

On my previous Omega it was a leak from a rotten head gasket (but that is unusual apparently)

[gbh]

Hopefully not the rocker covers i've just changed those.But when i was doing it i did notice this pinkish/white crystalised crud between oil cooler and head.I think i'll have to take the oil cooler plate off and reseal.I wonder can i use the same sealant as for the rocker covers?

[Andy H]

Hopefully not the rocker covers i've just changed those.But when i was doing it i did notice this pinkish/white crystalised crud between oil cooler and head.I think i'll have to take the oil cooler plate off and reseal.I wonder can i use the same sealant as for the rocker covers?

The cooler plate itself can corrode, it then leaks through pinholes in the plate 

[05omegav6]

£140 for parts, readily available on ebay, plus a tenner for the grey goo and a days work, including leaving the car unused for 24 hours once the cooler plate is stuck down...

[gbh]

Had a good look under today and with heating system off its weeping down the oil cooler pipes or on to them from above and then down by the crank sensor.With heating system on made no difference and the HBV is dry.From the top nothing to be seen so if i get the car up to temp and then strip the top down i may be quick enough to see the damp spot or i could use dye what do you think?It might be that the gasket is gone on the oil cooler so i can just replace that.Is there any play on the oil cooler pipes?

[Andy H]

When my previous V6 was weeping coolant in the same place I converted a cap for the header tank so I could pressurise the system without running the engine. Doing it this way allows you to take the inlet manifold and sandwich plate off so you can see the leak.

Pressure testing the cooling system

Mine turned out to be a leaking head gasket but I couldn't see it until I had lifted the engine out. In this photo I have got the system pressurised and coolant is dribbling down the back of the block from the head gasket.

[gbh]

Thanks,I hope its not the head gasket though.

[JamesV6CDX]

Thanks,I hope its not the head gasket though.

HIGHLY unlikely. The 2.6 uses a multi layer steel gasket, as opposed to the composite material used on the 2.5 and 3.0 (which does corrode over time and cause leaks at the back)

We have never seen a metal head gasket leak on an Omega on this forum.

I have a lot on work wise (applying for a new role etc and have a lot of revision to do) but I am happy to meet up again and have a look sometime in the not too distant future?

[gbh]

Hi James,Listening to the news I think you'll be rather busy,but if you're ever in the area please pop by for a cuppa anyway.Looking at that crunchy stuff by the oil cooler something must have caused that!!

[Andy H]

Hi James,Listening to the news I think you'll be rather busy,but if you're ever in the area please pop by for a cuppa anyway.Looking at that crunchy stuff by the oil cooler something must have caused that!!

Crunchy stuff on the oil cooler plate does point to that being the cause.

[Malcolm_D]

Recently cured a long term, and very annoying, water leak on my 2.6 It wasn't the HBV or the transfer pipe O-ring although I did replace these to rule them out. It did turn out to be the oil cooler cover plate sealant. Finally found it by stripping it down, thoroughly cleaning the suspect area and pressuring the system when cold, looked in the dark with a powerful torch and you could just see it slowly weeping. Before this I thought it was the power steering pump as the coolant ended up just under the AC compressor and evaporated leaving a slimy pink fluid just like ATF!
Decided to replace the oil cooler even though it looked in good condition (due to good maintenance i.e. keeping the coolant topped up and regularly replaced). Not too bad a job although getting to the bottom of the oil cooler pipes with a 19mm crows foot spanner was a pig! I also had to buy a full set just to get the 19mm I needed!
Happy days. 

[gbh]

An AA guy suggested i use Radweld!Any thoughts

[Andy H]

An AA guy suggested i use Radweld!Any thoughts

Have you done the pressure test?

I would only use radweld for a cars final journey to the scrappy. Budget for a new radiator and heater matrix if you do use it.

[05omegav6]

An AA guy suggested i use Radweld!Any thoughts

That's because he's an arse.

You could try replacing the oil cooler cover plate, sealing it with the correct sealant, and reassmble it, wait twenty four hours and then not have a leak...

Might as well change the oil cooler whilst your at it along with the thermostat for convenience, it's next to the oil cooler