I wouldn’t worry about that. Any pressure that collects under the valve cover is immediately exhausted into the intake manifold via that hose that connects your valve cover to the intake elbow. Blow in both sides to make sure neither side is blocked. That should alleviate pressure concerns. If you were going to have a problem, my guess would be from the hose going back into the valve cover.
If you’re not into trying that, then I can’t diagnose any further.
The screws are shouldered, so changing them isn’t going to do a thing for you, but replace them if that makes you feel better. I would suggest you replace all 13 of the little gaskets that go in with the bolts, however failing gaskets would only decrease the possibility of valve gaskets blowing out!
Short of a blockage in the camcover, I’d support the idea that the cover is either warped or aftermarket valve gaskets stink regardless of who makes them!
Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
22
If not plugged, that would prevent a gradual pressure buildup, but it might not prevent damage from an explosion in the crankcase. It’s important that there’s an actual flow through the crankcase to prevent the buildup of explosive gases.
Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
23
Somebody here please make up their minds. Better yet, someone please post a photo of the original screws and perhaps photos of the gasket, half moon, cam cover and top of engine with cover removed. Thanks!
Will do just that shortly, Kirby. Yes, I wondered when VK said that about the bolts … also, unlike the AJ16s, there are no “isolators” (i.e. rubber bushings/“washers”) that go with each of the screws for the AJ6s - just screws and washers (the latter of which are copper, but apparently steel ones work just as well and are re-usable).
Here is a diagram (from one of the usual Jag vendor suspect’s website) showing a comparison of the AJ6 valve cover assembly and that of the AJ16. Note that the AJ6 cover uses the machine screws + washers, whereas the AJ16 uses shouldered bolts + “isolators” (rubber bushings/washers) + (metal) washers.:
I’m not good at posting links. U do Google quite well. arp-bolts. You can go there and then to the catalog.
The long fastener I see down posts seem to have a POZI drive head. Similar to Phillips, but not quite as secure for the driver. For me reason enough to get a better bolt. Sealing flat washers are available. I forget the name.
Well, that crankcase is vented in some way. No pipe off the valve cover, finding it’s way to some limiting device and thence to the intake manifold???
With this question in mind search the engine bay and your documents. “How are the crankcase vapours removed in tis engine?”
PS:
That fastener seems rather generic. Take one down to your local Hardware like ACE. Mine has a great selection of fasteners and guys that know their stock…
The head matters little unless you insist on “original” I used head bolts from ARP
on my flat head V8. Male TORX.
And more than a few there and there on my Jaguar are Allen head. Most of the slotted heads are gone. I hate 'em…
Carl
Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
29
Really? I’ve found Pozidriv to be so vastly superior to Phillips that I get irritated when I run into Phillips.
Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
30
That looks like the '95-'96 cover (i.e. magnesium?). Note the black-headed bolts and isolators, which are consistent with that MY range. Also, it may be that the gold-toned screws on our '94s are posi-drive and not torx-head, as mentioned. I get those two names mixed up. One is “star” (what I call them) and the other is an “almost phillips but not quite” I just know I often mistake the “almost phillips” for phillips and by playing around with the fitment when r/ring them learn that they are of the other type and, FWIW, I agree with Kirby that the “others” are much more secure when driving in or out than phillips. btw, someone suggested the ACE idea to me, too (I think it was a dude in hardware section of Lowe’s) . I was about ready to try that route to locate new screws, but then I noticed a post by someone on here that the gold tone is actually indicative of a certain type of metal (or plating?) used for fasteners that have to sustain high temps w/o deforming/warping. My luck, I’d use regular metal type and they would deform and I’d have hell getting them back out again later on, if need for doing so were to arise.
Oops - to answer your question, no on the '94s there is just the “lip” on the underside of the cover and the matching groove is in the rubber gasket/seal. You install the gasket onto the cover before putting in place on top of the head and torquing down.
I kinda wondered about that, as I had read somewhere that the temp of V.C.s can get as high as 400+ F… However, I was talking to a local tech about that figure recently and he told me it was more like only 1/2 that high.
Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
37
Why not pick up pozidrive heads for yourself? Not expensive and it seems to give you grief. The #2 is really all you need…
You do not have a rubber hose connected to your valve cover??? Anywhere? I see one in the picture I’ve attached. Does that not exist on your valve cover?!?!
Agree, even “hardware store grade” fasteners
should do just fine, The “gold” is for looks!!
Yup, that hose off to left of the engine is more than likely the vent system. Track it down. Assure that it is clear all the way into the intake. that is where I think it is going.
I just know I often mistake the “almost phillips” for phillips and by playing around with the fitment when r/ring them learn that they are of the other type and, FWIW, I agree with Kirby that the “others” are much more secure when driving in or out than phillips. btw, someone suggested the ACE idea to me, too (I think it was a dude in hardware section of Lowe’s) . I was about ready to try that route to locate new screws, but then I noticed a post by someone on here that the gold tone is actually indicative of a certain type of metal (or plating?) used for fasteners that have to sustain high temps w/o deforming/warping. My luck, I’d use regular metal type and they would deform and I’d have hell getting them back out again later on, if need for doing so were to arise. 
