General Coolant cap not sealing!

[Meep]

Hi all, brand new member here so apologies of this isn't the best place for the post...

I've been having some bother with my 08 plate GP in that the coolant levels drop super quickly but there's no obvious signs of any leaks. I think I've narrowed it down to the cap on the reservoir itself not making a good seal/pressure valve being faulty - there's no build-up in the tank when hot and there's spray/spatter round about as if the coolant has been firing out rather than being contained...

Wondered if anyone else had the same issues and if there was an easy temp. fix until I can get a new part... speaking of new parts, any pointers on the best place to go? I did manage to find this (image attached) which is pretty similar to the OEM cap and apparently compatible....

 

[eeeno]

First, make sure that you have closed the cap tightly as it needs to make a click sound when completely closed and it needs some amount of power to accomplish that. There's these pieces of plastic that will hold the cap tightly closed.

Buy only the cap with same pressure rating which matches the part number. No mystery there. Many online part stores are happy to help you finding the right part by reg number and vin code. Good luck.

 

[Meep]

Thanks! It's definitely closed fully, those plastic tabs are a menace!
Managed to find an OEM cap on shop4parts so hopefully that'll be there on Monday to solve the issue

 

[portland_bill]

Sadly it is unlikely to be the cap at fault, although it may fail as a victim of the problem.

Most likely pressure from a head gasket leak.

 

[eeeno]

Did the new cap solve this problem? Check if thermostat gasket is leaking. It's a very common source of a leak. Sometimes it really is the cap and you can get away with it if replaced soon enough.

 

[Meep]

Sorry, been away for a few days celebrating birthdays!

The new cap seems to have sorted it for now… no more coolant loss and no signs of any leaks…

I’ve seen a few comments about the thermostat/head gasket being a source of issues in the cooling system though so I’ll keep my eye on it just to be sure… fingers crossed it was a rare example of it being just the cap!