Working on the '01 Bronze XK8, did the complete tensioner overhaul, water pump valley hoses, etc and my brand new valve cover (edit: I did not use a Mahle or Felpro kit; I used what came with my timing chain kit so this may be the root of the problem, will replace with MAHLE set and verify) gaskets are leaking on BOTH sides.... This was my 3rd time replacing XK8/R gasket sets, so not my first rodeo, but wondering what I could have done to possibly FAIL on both sides this time. I thought I examined the valve covers pretty well for cracks, and everything was cleaned thoroughly as the previous times on other cars, and followed the manual exactly regarding order of tighten and 9-11nm torque spec..

I've seen a few post about the rubber isolators not being made to spec as high, etc. and wondering if this could be the case. Both sides leaking backwards down the heat shield onto the exhaust manifold and leaking in front of the engine dripping on the ground. Not a small leak in combination, plus completely embarrassing at stoplights when smoke comes up...

Oh well, if anyone has seen this, let me know. Looks like I'll be tearing it down again to inspect and replace.

I also see the Lincoln LS Felpro sets are dirt cheap right now so may try those.

 

Lincoln Felpro worked great on my supercharged motor with the thinner black gaskets so it should fit the NA 27/28 motor.

 

I have not found information on whether those Lincoln LS Felpro gaskets are also suitable for the 4.2 SC engines. Do you know if they're acceptable in that application?

 

4.2 non-VVT valve covers and its gaskets have a different part number than the 99-03 4.0. I doubt it but who knows.

 

I had the same thing with the secondary tensioner "kit". The gaskets were fine but the little rubber grommets were too soft. That was like 8 or 9 years ago. No telling what comes in the "kit" today.

 

Im glad (or not) to know I'm not the only one. This wasn't my first rodeo with AJ valve covers, so when both sides started leaking, i knew something was up.

 

Had same issue with cam cover gaskets leaking at lower rear corner of cylinder head on both sides, resealed one side twice and still had minor seepage. At first thought that I might have cracked cam cover, but close inspection did not reveal any cracks. Finally went with felpro gaskets and a small amount of RTV just in the area of the leaks on both sides. No more oil leak.
This was a couple of months ago and Rock Auto had a close out for the Felpro kit, really inexpensive, not sure if they are still available.

 

I can confirm I used the nicely discounted Felpro gaskets from Rock Auto and they have absolutely fixed the leak on the '01 Craigslist Cat. Although I didn't want to do it, it gave me a chance to inspect my tensioners after 400+ miles. Everything was nice and clean and tight.

I cleaned up the mating surfaces, added new RTV to the correct gaps, and tightened per procedure.

With any luck, I'll be attempting some paintwork this spring.