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[Varche]

Did quite a long journey yesterday and was surprised to find I had used about a pint or so of water when I checked it today. It has always used a bit of water for years so I am not too worried UNTIL I looked underneath and found the orange stain down the passenger side of the engine to gearbox mating area.
Can't see anything up top leaking

Would I be right in thinking that this maybe coming from somewhere in the Vee? A banjo maybe? The oil cooler (which is the original factory one)?

Any suggestions on where to look and how( e.g. does the plenum have to come off?) would be gratefully appreciated.

El despondente Varche

[Andy H]

My Omega was leaking in that area when I first got it.

Found a receipt for a heater control valve in the paperwork,  spent lots of time looking for the problem but eventually found that my headgaskets were weeping coolant onto the DIS (ignition coils).

My theory is that a previous owner ran with a leaking heater valve & topped up with raw water which rotted the head gaskets

Whatever it is it is a pig to inspect. I had to take off the wiper motor just to get a mirror in to look for the leak when I pressure tested it

Good luck.

[Varche]

Andy H - so did you have to replace the head gasket then? I have been topping up with a mix of antifreeze and water but it hasn't been as accurate as doing a coolant change so maybe mine has "rotted" too.

I'm not liking the sound of a head gasket change one tiny bit.

[Andy H]

I ended up taking the cylinder heads off and getting a local machine shop to give them a light skim.

Before assuming the worst though you do need to pressure test the cooling system. I have an old pressure cap (from a Carlton/Omega A) that happens to fit the Omega B that I have drilled a hole in and fitted a Schrader valve to.

With a cold engine I can pump the cooling system up to 1 Atm (when the pressure relief valve opens) and take my time looking for a leak.

There is a jumble of rubber pipes behind the engine (including the heater control valve) which might leak. The pipes to the oil cooler are hidden under the inlet manifold in the vee. The oil cooler itself is immersed in oil in a well in the top of the block so a coolant leak here would be from the where the pipes connect to the top of the oil cooler.

I don't know what happens if the heater matrix leaks, it might find its way to the A/C condense drain pipes and drip out in the vicinity of the bell housing?

[alank46]

The oil cooler itself is immersed in oil in a well in the top of the block so a coolant leak here would be from the where the pipes connect to the top of the oil cooler.

Surely its the other way round, the oil cooler is immersed in water in the V of the block and the pipes carry oil?

[Andy H]

The oil cooler itself is immersed in oil in a well in the top of the block so a coolant leak here would be from the where the pipes connect to the top of the oil cooler.

Surely its the other way round, the oil cooler is immersed in water in the V of the block and the pipes carry oil?

Oops! I think you might be right. It was 5 years since I last saw the oil cooler.

I think the seals I was thinking of are on the coolant bridge (also hidden under the inlet manifold) a lump of aluminium that carries water from the rear of the cylinder heads and has the coolant temperature sensors screwed into it

[Varche]

So it might be the oil cooler connections?

I can't see it being the heater bypass valve as that is near the left bank rather than the right bank. It is the original but I have never seen liquid under the connections.

v

[Andy H]

I took the engine out to clean it up and do a pressure test. While it was out I took photos of it. Sorry about the quality, some time in 2003 I seem to have tried to copy the pictures to a cd & I cannot find the originals.


The first picture is of the rear of the engine while pressure testing the cooling system. The coolant bridge is visible & coolant is dribbling from the left hand cylinder head.

The second picture shows the top of the oil cooler. I suppose you could have a leak from around the nuts under the oil pipes or from the aluminium plate that the oil cooler is fixed to but I didn't find a leak on mine.

The aluminium lump to the left of the picture is the crankase breather / oil seperator. Mine was totally clogged with solidified oil & sludge. I spent a day trying to clean it but I eventually gave up and bought a new one.....