Hello fellow masochists!

As my parts begin to trickle in for the (hopefully) final major mechanical refresh of my XJ12, I have yet another question about parts! I'll be pulling off the upper sandwich plate, water pump, and harmonic balancer in order to replace gaskets and have the latter two preventatively rebuilt. However, I usually get a pretty severe case of "while we're in there" when doing these sorts of things, and I was toying with the idea of replacing my timing chain cover gaskets while I'm at it. The parts are cheap, so that's not a concern, but the way they seal against the head gaskets looks like I might be opening a pandora's box of introducing other leaks.

Considering that mine don't appear to be leaking at the moment, would you even consider doing this job as an add-on, or would you leave well enough alone?

 

If you are going that deep seems it would be a good idea to reseal the timing cover. It would give you a visual on the condition of the timing chain gear. New dampers might be a good idea if you can find them. New crank seal too right?

I don't know the intricacies of the cover gaskets vs. the heads, but hi-temp RTV as insurance could be useful. The classic V12 people will likely have some advice in XJ-S land.

I like high-maintenance things! V12 powered Jaguars, a 60 year old house, and living with a blonde woman! Though some things are easier to "fix" than others.

 

I now see how the heads seal up on the timing cover edges. Where the "1" points. I think I must reverse my previous "good idea" recommendation. Unless the heads are removed it would be near impossible not to ruin the head gaskets there. Memory refreshed.

 

Thats what I was thinking...

As I dove further into the rabbit hole of items to terrify me, I took a look at the timing chain tensioner and yikes. Its pretty much made entirely of plastic and tends to shatter if you try to release it. I was looking into replacing it preventively (AJV8 style) but after talking with an XJS specialist, it was recommended to not even consider touching it or removing the timing chain cover for that matter. Considering that I've only seen a handful of tensioner failures reported online, I think I'll just stick with the sandwich plate gasket and replace the timing cover rubber plug. Any further seems to be tempting fate.

Out of curiosity, other than watto700, has anyone else here experience issues with the timing chain tensioners on their 6.0 liters? Have any of you expressed or had any concern about them?