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Different Valve Covers?

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Old 01-07-2019, 01:50 PM
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Default Different Valve Covers?

Hello everyone - my friend just picked up a 1998 XJ8 with 74,000 mi and we are going through the car mechanically getting it ready for a trip from San Francisco to Texas.

I found oil pooled in the spark plug wells, took off the valve covers to inspect the gaskets and found that each valve cover has a different gasket profile. The left cover had a thinner grey gasket and separated spark plug gaskets. The right had a thicker orange gasket and connected spark plug gaskets. I know that these gaskets go by engine build date and from everything ive read online I think someone replaced the left cover at some point hence the different gaskets. I'm wondering if there is someone here with more experience on these cars can take a look at these photos to tell me what's going on here. I also want to make sure I purchase the correct gaskets for the valve covers themselves so if someone could provide the right part numbers that would be very helpful, I believe I have the spark plug/center ones figured out.

This community has been helpful for us in diagnosing and fixing a handful of issues, including the ABS light issue and very soon the plastic timing chain tensioners we just uncovered.
Thanks in advance!


left cover markings

right cover markings

both
 
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Old 01-10-2019, 08:51 AM
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The different gaskets are correct for the two different covers. You are right in assuming one of the covers was replaced at some point with the later version (thinner gray gasket).
 
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Old 01-10-2019, 10:00 AM
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Samilcar is correct about the orange & grey gaskets for the earlier valve covers. The new sets though come with the connected spark plug seals for both sides. I got mine from SNG Barrett, one of the board sponsors and they fit nicely when I did this job last summer.. Even better they seem to be sealed up, although I don't think they've even got 5k miles on them yet...I ran into lots of cracks in the plastic valve covers most of which seemed inconsequential but I did have to JBWeld a few of the steel compression limiters back into place before everything went back together. Yours may be in better shape. Don't forget to smear a little RTV over the seam between the front chain cover and the heads. No need to do this job twice!
 
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Old 01-10-2019, 11:40 AM
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Originally Posted by Samilcar View Post
The different gaskets are correct for the two different covers. You are right in assuming one of the covers was replaced at some point with the later version (thinner gray gasket).
Cool, thatís what my gut feeling was all along just wanted some peace of mind.

thank you!
 
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Old 01-10-2019, 02:23 PM
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The cam cover with the separate spark plug well seals ('B'bank) is likely from a later 4.0 supercharged engine (AJ27?)

All the AJ26 engines used the 'double' plug well seals with the 'slits' in the cam cover.

bob
 
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Old 01-10-2019, 08:50 PM
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Originally Posted by motorcarman View Post
The cam cover with the separate spark plug well seals ('B'bank) is likely from a later 4.0 supercharged engine (AJ27?)

All the AJ26 engines used the 'double' plug well seals with the 'slits' in the cam cover.

bob
Thatís odd. My 98 had the seperate gaskets.

ltd
 
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Old 01-10-2019, 08:55 PM
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So does mine. That's how I discovered the engine had been replaced at some point.
 
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Old 01-11-2019, 10:48 AM
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The 'double' connected spark plug boss seals are used To Engine (9810290000).

Replacement engines and people replacing covers/gaskets are some of reasons why there are different gaskets in the engines?

From engine (9810290001) onward should use NCE2578AA and NCE2577AC but there is a superseded part number for each.

If the cam cover has the 'slits' to hold the early 'double' plug boss seals, then that is what should be used!!

bob
 
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