Hi
I have Jaguar S-Type 2008, 6V
I had issue with water pump and I already replaced it
After one month of the replacement of the water pump I saw there a little oil in the water reservoir tank and cap of reservoir tank only
I checked the engine oil, it totally clean and there is no water inside engine at all
The oil only inside the reservoir tank
I attached photos for the oil inside the reservoir tank
Any suggestion ??

Note : Car never get hot, and the transmission working well.







Thanks
Black

 

Are you running coolant or plain water? In the picture, the liquid looks very clear, as if just water.

Are you positive the froth you're seeing is from oil?

I'd suggest doing a pressure test of the cooling system. This uses a simple tester that looks like a bicycle pump. It connects in place of the cap on the reservoir. You pump up the system to the rated pressure marked on the cap. Let it sit for 15 minutes and check the gauge. It shouldn't drop more than a needle’s width.

If the pressure test is good, the cooling system is sealed tight. Oil would have no way to get in. If you don't have a pressure tester, many auto parts stores have free loaners.

 

What Karl said...

Also, running straight water in the cooling system is a bad idea, even if you live in an area which does not experience extreme temperatures. Coolant contains corrosion inhibitors which are needed to keep your cooling system and engine block happy...

 

+1 on the above two replies.