I was looking at a couple of Jag XJS cars on EBAY. I noticed that from 1994 to the end the 4.0 cars had the same cam cover as the X300 4.0 cars. But the covers on the XJS cars looked to be very smooth and in perfect condition unlike most of our X300 covers which is due to the X300 covers being made out of magnesium. My question for the XJS guys is, are these cam covers on your cars also made out of magnesium? Or were they smart enough then to use aluminum?

Looking forward to your comments.

 

MY94 XJS and XJ6 (XJ40) for that matter, both used the AJ6 engine. The MY95 XJS and X300 used the AJ16. The valve covers are completely different for each engine. The MY95 cars all had magnesium covers.

 

Near as I can tell part number NBC2564CB Camshaft Cover was the same for all AJ16 engines whether installed in an XJS or X300.

An alternate number, NBC2564CA is shown but there's nothing to describe what the difference is. Like the "CB" variant, it shows both XJS and X300 usage.

I think most XJSs see less use than X300s so the cam covers simply stay pretty longer. The cover on my XJR was almost pristine until about 100k miles.

Cheers
DD

 

All AJ16, X300 or XJS engines used the same gray magnesium covers that eventually turn to dust.

 

You meAn the paint on the covers turn to dust, right?

 

Nope. I mean the covers themselves. Until I replaced mine with a NOS part I found, it leaked oil into the coils, and no amount of adjusting or new gaskets would totally solve the problem. They tend to corrode and turn to crap.

 

It really was a dopey idea switching to a magnesium cover. The cover on my new to me XJ6 is in a state, with corrosion all over it. Unattended to it will quickly eat through the material. When I refurbish it, I may look at some alternative materials to coat cover and especially the plug wells, some kind of high dielectric epoxy or perhaps ceramic powder coating?

Meanwhile the alloy cover on my XJS looks as good as day one. The Jaguar experiment with magnesium covers did not last long and for good reason!!

 

Allen, if you come up with a coating you think is going to work please share your info. I now have a spare that is in pretty good shape and would like to coat it with some material that will control this electrolysis. I am presently considering power coating or a good two part epoxy paint. I think the paint idea is presently the best bet. Of course the main problem is the plug wells. I'm not sure it wouldn't be bad idea to coat the inside of the wells with JB Weld.

 

While not nearly as durable as powder coating, Dupli-Color Paints offers a line of paint called Engine Enamel Dupli-Color :: Engine Paint with Ceramic, which incorporates ceramic resins. Although the current products only seem to go up to 500°F, I have several cans of NOS aluminum color (product number CDF1606), which looks & feels great, and is rated to 1200°F.

VHT Paints also offers engine enamel with ceramic resins. It is rated to 550°F. They also have a line called Engine Metallic, which is rated to 650°F, as well as their Flameproof line of paint, with a silicone ceramic base, which is rated up to2000°F. The Only problem I have with the Flameproof line is that it is only offered in a matte finish. VHT FlameProof™ Coating

 

I have a 96, so I'm going to assume it's also magnesium.

Replacing it with a similar part doesn't really seem to solve The problem.

Finding a part and then coating it, as suggested above seems to be the right solution, doesn't it?

Surprised I haven't come across this before...

I'd like to resolve this issue permanently.

 

It does solve it for several years. These did not go bad in 5 years. I tried to see how to fit the cover from a
aJ6 into my engine but the definitive answer was that it could not be done.

 

I did consider that (using the AJ6 cover). Thanks for killing that thought immediately.

Looks like I'll get it powder coated. That should solve the problem?

 

One thing about powder coating is that they sand blast the surface before applying the powder. Depending ont the condition of your spark plug wells there is a good chance they will sand blast right through the plug well walls.

One thing that I think will help and we all should do regardless as to what paint or surface protection we apply and that is to use a dielectric grease on both sides of the new coil gasket and on the threads of the coil attach bolts. The idea is to isolate the coils as much as possible from the can cover itself.

 

I have a correction to my original thread. The XJS and the XJ6 (X300) both shared the same engine starting in 1995. The 1994 XJS is totally different than the X300. But the 1995 XJS has the same engine and cam cover as the 1995+ X300 to the best of my knowledge.

 

I don't know if it will help but there are two different aluminum AJ6 valve covers, the one used through 93 with a remote oil filler and fewer hold down bolts and the 94 only, with built in oil filler and more hold down bolts. I don't know if the 94 aluminum valve cover would work to replace the magnesium one. I always liked the look of the 95-96 valve cover, I had no idea it was made out of magnesium.

 

Has any one done a powder-coated cover and if so how is it holding up

I was going to use the engine enamel paint have used it extensively on my Capri X pack resto
when its been left out in the sun for a week it gets pretty hard

 

https://www.jaguarforums.com/forum/s...ad.php?t=72047

This may help.

Again, yes the 4.0 na AJ16 engine, including cam covers is exactly the same on x300's and 95-96 XJS's and no, no cam cover from a Aj6 car, even very late model, will work

 

Basically, the other thread got to the same conclusion we did: will powder coating it solve the problem?

I know that the shop will have to be careful, but is it possible, and is it worth doing? I'd hate to have it done only to find that it flakes off, or causes some other problem.

The Aston Martin cover was a good idea....

 

Or ceramic coating?

I dunno. Just throwin' it out there

Cheers
DD

 

Did anyone do any testing with powder coating or ceramic coating?

One additional question is: Will the "wool" up under the cam cover that is a filter for the vapor recovery vent "melt" when powder or ceramic coated? Is that filter material metal or plastic and will it hold up to the heat of coating?

.