Engines that are run long enough, get the oil hot, have no moisture in the engine or the oil can be running in the wet, stop and parked with a hot engine and then H20 gets sooked in. Much the same thing as condensation under other circumstances.

 

Plant and 4x4's or the likes can have 'Axle Breathers' and that is so you can wade in water.

Where the breather goes up high on the vehicle but has no non return valve you can have hot oil in the diff and then stop and as the oil cools H20 gets sooked in.

Finally got my compression tester working properly so it holds the pressure and lets it build up and got results more like I was expecting from other cars I've tested:

1) 32 bar

2) 31.5 bar

3) 32 bar

4) 31 bar

So nearly a week after I started trying to find a garage to do the test, I have definitely ruled out the cylinder head and gasket!

(minimum is 19 bar with max difference of 5 bar between cylinders so everything is well in)

 

Double checked temperature with VCDS, not a very comprehensive test this evening but it looks like the gauge does move as the temp goes up and down, but it reads 15C higher than engine management is seeing. I assume mine is one of the engines which has 2 sensors, I suppose it is possible that because I only just ran for long enough to get to 90 on the gauge that the temperature may not have evened out through the system (one on the engine, the other at the radiator), but the radiator one would be for the gauge and that should be cooler because the radiator is bypassed until the temp gets high enough to open the stat so probably one of the sensors is duff.

 

The fact that there is no oil mixing with the coolant makes me think it probably isn't the oil cooler.

 

I didn't check the air ducts or filter because it is hammering down with rain here and I would be introducing moisture not finding it!

 

Starting to look very much like it is just running cool and not clearing the vapour out of the engine. I guess it is time to look at the the thermostat and temp sensors, they are usually pretty cheap, and not likely to lead to catastrophic failure in the mean time.

 

Thanks for the help guys!

 

 

 

 

2 minutes ago, Jim-octavia said:

Starting to look very much like it is just running cool and not clearing the vapour out of the engine.

Which is what I thought from the word "go".

Just do an oil and filter change and keep your eye on it. It's been Biblically wet/damp recently so plenty of moisture in the air.