Just removed the valve cover on my 199k-mile XJR6, and am encountering things that many members of this forum have mentioned before. One of the previous owners overtorqued the bolts to the point where the gaskets for the bolt holes were visibly split, and you can even see this in engine bay shots from the for sale ad as posted on Cars and Bids last year.

The damage to the bolt hole gaskets was enough to have oil practically pouring out from under the main seal around the valve cover, and it came off without any effort once all the bolts were loose. After removing the valve cover, I noticed that one of the spark plug holes was no longer oval, as you can see here. Interestingly enough that particular spark plug well looked pretty dry, so the spark plug gasket seal wasn't affected by the funky shape.

The thing that really gave me pause was this chunk of plastic that fell out when I removed the valve cover, coming from the front of the engine where the timing chain is located. It seems to have been chewed up by the timing chain at some point, but the engine itself has been running fine without any noticeable rattling. Could this have come from one of the chain guides or tensioners?

 

Hey guy,

Yes that looks like a piece of timing chain guide to me. Evidence of the duplex links. Good for you that piece is not sitting at the bottom of the chain cover (although there are probably many bits collected there at 197k). Minimal worry with this as the timing chain and guides are very durable (aside from the plastic guide pieces) and without undue noise or rattle a full rebuild can safely wait. Chain jumps are very rare with the AJ16, touch wood. Without noise your chain tensioners are working too. Don't switch to a "thinner" oil like 5W.

Since you have the cover off you probably noticed the bolts for the valve cover have a shoulder. That prevents them from creating too much pressure on the gasket. But as you know the bolt grommets will split and leak. So use the genuine Jaguar gaskets. Then this is a one-time job.

 

Thanks for the reassurance; a spirited drive confirms that it isn't heading toward its doom, still no rattles or untoward noises from the front of the engine. Annoyingly the gaskets now look wet on the outside after the drive; given the age and mileage of the car, it's hard to tell if the valve cover itself is on its way out, or these Uro-branded gaskets are to blame. Until these things split again, I'm just going to keep topping up the oil and not think too hard about these leaks.

 

that spark plug well looks nowhere near as bad as mine did. i recently did a huger restoration on my valve cover. just make sure it has a flat surface to it when you reinstalll.

 

Well, after putting it all back together, it still leaks a ton of oil from the gaskets. Took it apart and looked at everything, and there looks to be a lot of paint flaking off of the valve cover in the grooves where the gasket sits, among other places. I'm considering applying a lot of RTV anaerobic gasket maker to get it to seal better; do other folks have recommendations on using normal RTV or something else to improve the sealing?

EDIT: After searching around on the forum, it looks like I made a mistake by using an aftermarket gasket. I've just ordered an OEM gasket and will add RTV anaerobic gasket maker on each of the bolt washers just to be on the safe side.

 

Whew, fingers crossed, but it looks like the combination of an OEM gasket and sealing both sides of every seal (bolt isolators, spark plug well seals, and the main gasket) with anaerobic gasket maker has done the trick, and 30 minutes of highway driving no longer comes with oil pouring onto the driveway and a cloud of oily smoke. It is hilarious how misaligned everything is though; the outside of the valve cover isn't lined up with the edges of the head, and the spark plug holes in the head are off-center from the ones on the valve cover. If this were a German car somebody would've been shot.

 

I just redid my gasket too. Mine never seem to last too long. Maybe a year? I’m wondering if gasketmaker isn’t the way to go, but I shudder at the thought of cleaning it up when I have to get back in there.

 

with all the hard work put into mine i wonder how long it will last?
got the surfaces as even and level as possible, and used the gaskets along with a nice bead of rtv.

 

I've got to assume that the RTV will prolong the life of your work significantly.

If you happen to remember, can you let me know when your gasket fails? I will do the same.

Just for record, I did use fuel resistant gasket sealer....Hylomar AF.

 

I have to correct myself, I used Permatex anaerobic gasket maker on mine; it'd be good to compare different types of sealant over time. I don't drive my XJR much so it'll probably last a while.