Thanks guys. I am building a shopping list, and it's very confusing, to be honest. Sean, I don't understand this - "do a pulley upgrade, the later R runs a different idler tensioner bracket and belt, also see if you can match them for the accessory belt in metal. I'd be inclined to do a lower pulley upgrade for the s/c too while down."

Which pulley are you talking about? I've read about the 4.2 lower pulley, but since that requires a 4.2 timing cover, it could get expensive.

I am replacing two idlers, and a bearing in a 3rd metal pulley. I don't mind plastic too much, especially if it's new and inexpensive. I'll price out metal though.

I was thinking of posting my shopping list, and perhaps in a new thread to get maximum visibility. What do you think?

Thanks

 

Actually your failure mode looks pretty much like mine!
And in pretty much the same place!

 

Why can't I find any crankshaft information in JTIS? No torque vales, bearing information, or procedure. Con rods, yes, but no crank. I found that water was in the oil and I am wondering if there's any bearing damage. The con rods are easy to do, but why not the crank, I wonder.

 

If you are going to do a pulley upgrade, on the 4.0 going to a larger lower pulley will give you about 4.5 psi of boost vs about 3 psi for the smallest of the s/c pulleys. Plus changing to a smaller s/c pulley requires shaving the snout. Going to a larger lower pulley will get you about 50 HP in mid- range. Plus no irreversible modification.

 

Ah, but which lower pulley? From what manufacturer?

 

Try this link:
Jaguar Supercharger Upgrade | Jaguar Supercharger

There you will find +/- for upper & lower (both) mods.

 

Lawson is good to deal with regards the above link posted by TF...if you decide to add power, you'll need a slightly shorter belt to go with it, the original will not fit...

As your refreshing bearings no problem on the pulleys.

 

You need to download the engine repair course manual originally posted by motorcarman.

 

Was that the '99 or '02?

 

Well ,the 4.2 idea didn't go anywhere, so I am back to fixing the 4.0. The only holdup now is my confusion over which headgasket to buy.

Any ideas, I'd be happy to hear them.

Thanks

 

plums:
Sorry about taking so long to reply... I did not see your post. It was my MY99 XJR with 175,000 miles. No overheat, and no real warning, although I am now showing high LTFT on the bank that the blown gasket was on. I am afraid I may have a plugged injector, and maybe it is running lean. However, the gasket looks to me like it crushed incorrectly on initial assembly. What do you think?
I am not driving it until i figure it out. I just have not had time to go at it with the scope. I will probably build a injector balance tester, or just break down and buy one.

 

The blowout of the fire ring looks like others that have been pictured in other threads.

As you may know the 4.2L gasket is a MLS type and known to fit the AJ27 4.0L. Others might know if it also fits the AJ26.

Now, the reason I have been recently been asking/tracking/searching what years tend to blow head gaskets is a little snippet of information in the technical documentation that notes a running change to a MLS type in the 2001 model year superceding the use of the conventional composition gasket with fire ring. Perhaps the same as used in the 4.2L. Searches through past threads would seem to support a hypothesis that it is the 2000 and earlier v8's which have had blown head gaskets and not 2001 model year and onwards.

BTW, DexCool is known to attack silicone, nylon66 and swell composition head gaskets. See that tear next to the fire ring in AVT007's failed gasket?

 

Yeah, I noticed that, but mine had no such distortion. The crush marks on the "fire ring" for the cylinder in question on my gasket can be seen pretty well, and on AVTs , it looks like it has the same shape, although not as well defined. It looks to me as if the ring was displaced inwards during assembly and eventuaklly burned.
In any case, I would agree with you that the MLS style gasket should not have the failure modes that these two showed. Since I do not intend to push this old engine, I figured the stock gasket should do fine as long as I carefully cleaned the mating surfaces (they shined like a mirror!) and followed the tightning procedure carefully.

 

BTW, which cylinder failed?

 

The firstor front cylinder on the LH bank failed. However, 7 out of 8 cylinders had the same failure mode of the gasket.
This is why I am looking for a better gasket.

 

Plums:
In mine, it was B2 or B3, as I recall.

 

If yours counts as a AJ27, then the 4.2 MLS is the suggested choice.

If it is a AJ26, then see if the AJ26/AJ27 gasket number are the same. If so, then again go for the MLS from the 4.2L.

Maybe someone like XKRacer will chime in on the early engine.

You could also contact cometic who make a MLS gasket and ask them if they are indeed the same part number or if they have one for your specific engine.

BTW, others have found that the Lincoln LS head gasket does *not* fit due to a difference in the oil return passage at the front.

 

FWIW, Wikipedia says it is an AJ26S. S for supercharged.
And Cometic doesn't list the AJ26 or 27 engine on their website.

Here's the EPC for my car:

 

Well, assembly has begun. [IMG][/IMG]The LH cylinder is in place, awaiting my new torque wrench. Next is the RH head, replacing the valve seals and cleaning up the seats.
It's nice to see pieces going back on to the block!
[IMG][/IMG]

 

I have no proof it is important, but Andy Bernstein (not Stodart!) who used to hang around Jag forums swore that having the mating surfaces shiny clean helped prevent headgasket failures. I got mine like to not quite mirrors!