New member here and new owner of a gorgeous XK8.
Checking the coolant level today in the expansion tank (OK) and the pressure cap came apart in several pieces. Put it back together and reinstalled, but suspect this is not normal. Ordered a new replacement cap. Am I on the right track?

Well, certainly it needed a new cap. But it may be indicative of deeper issues. If that cap, which is pretty sturdy, fell apart, how much more plastic stuff is on the verge of joining the enemy? I'd consider going on a preventative maintenance spree before something expensive happens.

I wouldn't be surprised to hear that the header tank was not filled to the brim ..... which means that the atmospheric expansion tank is empty. It's very common with XK8s.

Richard

This exact same thing happened to me about 2 weeks ago. It was a cap I purchased on ebay last year and was made in China. Just bought another from Oreilly's and is also made in China, but works for now.

Jack

Expansion tank was at normal level.

normal level is 100% full when the engine is cold..

note: the expansion tank cap seals with 2 O-rings. Just put it on snug If you tighten it really tight it won’t last long.

the o-rings seal just fine without much cap tightening. I learned that on this forum.

Z

As @kstevusa mentioned, always back the cap off a little. It will last a lot longer that way

​​​​​​​Z

I'm just wondering why the update a year later? 🤔

​​​​​​​Richard

Hello “leave-no-stone-unturned” Richard,


early onset Alzheimer’s is a good possibility.

Z

I wouldn't worry about Alzheimers, zray, you just replied to the wrong thread. There is a current thread entitled "Coolant Overflow Tank Cap" also started by MV Monarchthat you have been posting to that you took that quote by ksteve from. As someone else said in that thread, " Words matter.
Best,
Rick

Motorman,

I'm sorry I didn't properly identify you as the source of the quote that I also mangled in the post, above. I've benefitted from your knowledge and experience often and sincerely apologize. My problem is that I don't know how to edit my posts without losing them and starting over. Maybe I need to write them out before I start entering them on my phone.
Best,
Rick