Head gasket or oil cooler?

[Dan-87]

Hi all I’m a new member having just purchased a mk5 gti as a project,it was sold as needing a head gasket-there is oil in coolant and also coolant in the oil-looking around it doesn’t seem too much of a common issue on these but I’m aware the oil cooler can be problematic? Question is,is it likely that due to a failed oil cooler the coolant and oil mixes both ways or is it usually just oil in the coolant?
Obviously the cooler is much cheaper and easier so I’m tempted to start with that,I’ve only got previous owners info to go off at the minute which I don’t really want to take as gospel I need to be starting afresh with it,for now I’m just curious as to wether anyone has experienced oil in coolant AND coolant in oil due to a failed cooler?

[titchy]

get the cooling system pressure tested

[LC5F]

Not experienced an oil cooler failure myself - but they do occur - the VW design has not really changed since they realised water was a better coolant than air.

Due to pressure differences, oil tends to be the first to break into the coolant, once engine is stopped the coolant then gets a go to mix with the oil. over time the split opens up more and both liquids can mix easily.
To confirm its the cooler I would pressure test the coolant connections.

If it is just the cooler this could be a nice cheap fix.

[Stupots]

The oil cooler failed on my girlfriends Mk1 TT. I didn't know that was the problem, but there was oil in the coolant... I replaced the oil cooler in situ (It's pretty easy to get to on a Golf also) and then flushed the coolant system through with a proper flush meant for the job... problem solved.

If it's the head gasket it does tend to only put water in the oil, so finger crossed. The only way you'll know is to do proper pressure testing as @titchy says, but an oil cooler is about £25 and will take you a couple of hours, so worth doing.

Certainly on TTs it wasn't unheard of for them to fail, especially after a water pump change strangely, which is exactly what my other half had done a few weeks before the problem... odd.

Good luck!

[Dan-87]

Thanks guys,I don’t have access at the min to the coolant pressure tester although I have got a cylinder leakage tester on the way,I have a compression tester and have carried out a test tonight,cold engine dry test gave 175psi ish and was even across all 4 cylinders

I obviously don’t want to start stripping head off if I don’t have to,following on from the positive compression test results tonight I think the oil cooler,for the money and time it’ll take me,seems like it’s worth doing