Hi, I have a problem with coolant leaking from the header tank on my 1998 XJ8L. I noticed there is an expansion tank as well. What is the purpose of the header tank if theres an expansion tank? How can this issue be resolved. Thanks

 

Can you see where it's coming from? And how bad is it?

 

it is coming from the top of the tank, when the engine gets hot it starts to leak only from the header tank not from the expansion tank

 

OK, have you pulled the plastic cover off so you can see the whole tank? I mean that big flat plastic piece that makes it look tidy, hiding all the oily bits.

Double check that the cap is actually screwing down properly. Both my XJ8s have a thing where if the threads don't catch right, it feels like it's on, but it isn't. Watch as you turn it, looking to see if it actually travels down the threads.

Can you see exactly where it is leaking from? Does it look cracked?

If that isn't it, look for the condition of the oil. Does it look like a chocolate milkshake. It's possible that you have a bad headgasket and it is pressurizing the coolant system.