Valve cover nuts

The torque figure is 6 Ft lbs. But wrenches (spanners) were made in specific lengths. the bigger the fastener head the longer the wrench, A 7/16 wrench was 5-6 inches. The early engineers worked out that an average man using such a wrench would be able to tighten it correctly, this worked for all sizes and types of fasteners. Of course when torque wrenches were designed it made it easier and today you can find a 7/16 which is 12' long.

It's a good idea to anneal the washers before reuse. You do this by putting them on a wire and heating to red hot for a minute or two. Let them cool, and they will have regained their ductility and should seal better. Be careful to put the flat side against the cover, providing that there are not nut indentations on both sides. Hardware washers are ok, but should possibly be annealed also, as you don't know their hardness. Hardware washers are also too big and would be an obvious deduct in a Concours.

If you are truly anal about this, it is possible to put a tiny bit of sealer on each washer to seal them...

Edited on 2008-10-07 11:01:57

Chuck, you don't mention which series car you have. If Series 1, read below.

I have a theory on WHY Series-1 cam cover bolts leak and crack. But to answer your question, I have never seen a specific torque setting for these nuts in a manual. DoesnÔÇÖt mean there isnÔÇÖt one though. Seems Jaguar improved on these cam covers in the Series 2 and 3, making them stronger and less prone to cracking.

But in regards to Series one cam covers, follow me on this. What is the first thing a mechanic or owner does when he opens the bonnet and sees leaking at the cam cover nuts? Naturally, he grabs a wrench and tightens the nut. Do this enough times and pretty soon small cracks form around the hole, making the leak even worse, and the repair ultimately more difficult and expensive. And if the holes have cracks, tightening the nuts simply enlarge the cracks, making the leak worse.

In their wisdom, Jaguar used copper washers under these nuts. Why? Because at the time, it was the only material on hand that could withstand the high engine temps while providing a good seal. So why do they leak? Short answer: You cannot re-use the copper washers, period.

When you put a new, flat copper washer on the stud and then tighten down on it, the soft copper indents to that studs specific location in relation to the hole, as well as the nut sealing on top of the washer. Every hole, every stud, and every nut is minutely different.
What most people do wrong (it took me a while to realize this myself) is when they remove the cam covers for whatever reason, they throw the washers and nuts together into a little pile. They then re-install the washers and nuts, not giving it much thought, right? But what happens is that the used, deformed washer is NOW on a stud that it never sealed. And because it is already deformed from the previous position (stud), it is not pliable enough to reseal or reshape itself to this now ÔÇ£differentÔÇØ stud and nut, which causes it to leak, which causes owners to over-tighten the nuts to the point of cracking the cam cover.

SOwhenever you remove a cam nut and a copper washer, you MUST reinstall new, flat copper washers otherwise it will not properly seal. Luckily, these are fairly cheap, and I think you can find them at most Ace/True Value stores.best to buy a box if you find them. Of course, if you dont care about concours originality, then you can probably find nylon, fiber, or Teflon washers that will do as good a job.

In regards to tightening down on the copper washers, I usually finger tighten, then go ?? turn on the wrench. Since practicing this method of replacing with new copper washers, I have NEVER had a leak at the cam cover nuts.

The copper washer CAN NOT seal any cracks adjacent to the hole. If you have cracks, you must take the cam cover off, thoroughly clean the inside surface, and apply an epoxy to seal the crack. Much more expensive is to weld the cracks shut and re-machine the flats and stud hole. Frankly, IÔÇÖd just as soon buy a new pair of cam covers ($$$) before going to that extent. Or just live with it. All depends on how you use and maintain your Jag. (If you are lucky, you might find a set of covers on EPay that do not have cracks at the holes...make certain you ask before bidding, otherwise your just buying someone else's junk)

Hope this helps.

Patrick McLoad
JC Houston

PS: If your leak is down at the cam cover gaskets, tightening the cam cover nuts probably isn't going to fix the problem. I have personally never had any luck with the silicone gasket stuff in a tube. I always coat both sides of a cam cover gasket with the brush-on Permatex Aviation gasket sealer (do this on a piece of cardboard). Yep, its a nasty job, but it works. Wipe off any excess with thinner or alcohol, being careful not to remove any gold or pumpkin color head paint.