2000 XJ8, 52,000 miles. 1 year ago my (former) mechanic replaced both valve cover gaskets, valve cover seats, all spark plugs, spark plug seals, clean out breather lines/hoses.

Now, 1 year later, I just started to have a burning smell in the engine compartment. I traced it to a small oil leak on the passenger side in the back corner of the valve cover. Just under the back corner 10mm bolt. I checked & the bolt seems tight. (closest to the firewall)

I assume the oil drips onto the hot manifold & burns. I’ve been wiping it up daily (maybe a spot the size of a dime) which has mostly eliminated the odor. How can it be leaking so soon after the gasket was replaced? Does this suggest an incompetent job replacing the valve cover gasket or something else? If the gasket needs to be replaced again, I will probably have a mechanic do it as it seems fairly involved.

If I need to bring it in to the Jaguar dealer to redo the valve cover gasket (I don’t know a trustworthy, competent mechanic in Phoenix, AZ) I wonder if I should have them inspect & replace the secondary tensioners with the metal ones. I assume mine are plastic & will break. I do not hear any noises suggesting this has happened though. Also to inspect -- but not replace unless damaged -- the primary tensioners, chains, chain guides. Anything else to replace as preventative maintenance as long as they already have done the disassembly? I had replaced the thermostat myself in 2004 but not the water pump.

BTW, is the valve cover the same as the cam cover? Under the Ignition coil cover on both sides of the engine?

Thanks,

Steve

 

The tensioners are really not difficult and can be changed for less than $200 in parts and tool rental including the gasket set. You are going to spent $1200 plus at the dealer. And yes, removing the valve cover, which is leaking, exposes the tensioners for replacement. Here is a link found in the XK8/R Forum FAQ Sticky to a great pictorial of the work if you are interested in trying it yourself:

http://www.mediafire.com/?mijhydngtog

I am sure some of your Jaguar neighbors in Phoenix can recommend a reliable independent shop if you chose not to change them yourself.

I would refer to the gaskets as seals and suggest that they leak more often from over tightening the cover bolts than anything else.

Also, you cannot effectively inspect the primary chains and tensioners and guides without removing the front engine cover which involves the majority of the cost of doing the complete job.

The tensioner work does not affect the cooling system so there is no financial advantage to having that work done at the same time. Your '00 car is past the critical water pump failure era and since the pumps tend to fail gracefully I might wait until there is a sign of coolant leakage in that area.

Tight Wad Tom (my wife's affectionate nickname for me)

 

Many people change the gaskets/seals but don't change the rubber isolators (NCA2575CA). The old ones collapse and the the new ones add clamping force to the cam cover. I think there are 14 per cam cover.

bob gauff

 

Thanks Test point, great link to PDF how to document. Based on the pic I see that The valve cover and Cam cover are the same. So, one possibility is my (bad) mechanic had over tightened cover bolt or bolts. Work must be redone. The procedure described for tensioners seems lengthy & complex with many places for error. I don’t have a helper so removing the hood w/ damage would be very difficult. I never have used a torque wrench so looked up some video on doing so & seems fairly simple once you purchase the tool. Yet, the tool seemed very large & some of the bolts are in hard to reach locations. I wonder if this is a shortcut taken by some bad mechanics who can’t reach (for example) the back corner bolt (that is the leaking area on mine) & chose to use a regular smaller wrench to get that last bolt & over or under tighten it. Speculation I know but, to have it leak 1 year after spending much money is beyond annoying.

Motorman, these rubber isolators are called gaskets for the camshaft cover bolts in the PDF how to document linked to by Test point. So there is another possibility for error by a bad mechanic. I don’t know if when you order parts from Jaguar they come in a kit where you get the valve cover gasket plus the many little gaskets or isolator for each side or if you must order them separately. My guess would be ordered separately. So, perhaps on other types of cars you do not need to replace these many little gaskets so, a sloppy mechanic would assume it is the same for Jags & just look up the valve cover gasket part number & order that only & not bother to look up any procedural information.

Maybe he failed to apply RTV silicone or did so improperly?

I would not have known there was a leak if it didn’t smell like burning oil. I am certainly going to check all along the edges of the valve covers after any future repair especially before the typical 12 month warranty expires.

Steve

 

I cannot buy some RTV silicone & smear it around the back edge of the Valve cover where it is leaking, can I? Wouldn’t work I’m guessing.

One can hope <GRIN>

Steve

 

Nope.

 

I have seen valve covers cracked in the corner from overtightening the valve covers on these cars. Not that much torque is needed, like 10Nm I believe. Remove the cover and inspects that outer edges of each bolt hole.

 

I have seen this happen on many other models too. People think that just because the grommets dont come with the other gaskets, they arent part of the valve cover replacement requirements. When he unseated them from their original position and tightened them down into a new one, the grommets arent always able to conform to the new shape. I am up for doing my VCs soon also and I can tell you 100% that I will be replacing the "grommets" while I am at it.

What about the seals for the VCT solenoids? Do they come with the fel pro kit? I will most likely be using fel pro on this is why I ask.

 

I just checked my 12-2009 invoice from the former, bad mechanic. I was charged for 2 valve cover gaskets & 28 valve cover seals so they must have replaced all. Probably overtightened bolt. I just checked with Jaguar dealer & total will be $475 to redo the valve cover gasket on just that side (Passenger side). It is very tempting to do it myself. I have successfully replaced an ignition coil so, I know how to remove all that stuff & put it back. But, I have no torque wrench & not sure what type I’d need to buy to ensure it can reach all the bolts. Also, I didn’t understand the how to instructions for putting on the RTV silicone. Don’t know exactly where to apply it. My 1st thought would be to run a bead all along the entire large gasket but, I think I am supposed to apply a specific, exact measured, amount to only certain spots. Whether I end up doing it or Jaguar does it I sure hope the former mechanic has not cracked the VC which probably cost hundreds to replace.

 

You only need to put silicone in places where there will be a seam under the rubber gasket. For example the joint, or seam, where the timing cover meets the cylinder head creates the valve cover gasket mating surface, is one of the places needing silicone. With rubber seals there is no need for silicone unless something in the area requires a little extra "filler." The gaskets do look easy to change, I will give it that.

You would also need an in-lbs torque wrench that can start out as low as 40in-lbs or so to properly torque it down. I will have to check out torque specs, but usually VC bolts torque down around 100-125 in-lbs which is very easily attainable by hand.

 

You will have to get the VVT seals separately. Autohaus is at least one that has them. I had success with Felpro gaskets when some of the other generic ones failed.

 

Yes, wise advice. These cam cover seals do NOT need any assistance from gasket sealants. Another tip - you don't really need any silicone on the part lines if the factory sealant dab is undisturbed. Only use silicone sealant on the part lines if the front timing cover was taken off. I've been doing customers' cars like this for years now and never had a leak.

The MOST sound advice in this entire thread is proper torque. If the cam cover bolts are overtightened, even by a modest amount, you can be guaranteed an oil leak and it won't make much difference at that point whether you put the cover on dry or with silicone, or even peanut butter for that matter.

 

Agree with everyone about torquing the bolts correctly..... when I did mine I checked the torque setting from 3 different places because it did seem very low. When I torqued the bolts to the correct setting I was almost sure something was wrong because it just didn't feel tight enough..... however, I stuck with it, kept them at the correct torque and have had no leaks after 1 year.

And yes, this is the ideal time to do the yucky plastic top tensioners too.... There's a lot of debate on this forum about which method to use. For sure the correct method is using the special tool and it's totally understandable the Jag techs recommend and use this method, as they are doing so on customers cars and need to be 100% sure its done properly. There is another short cut way of doing it (loosening the bolts on the outer cam and lifting it slightly while pulling the tensioner out) which has also been successful for many people when working on their own cars, but again, it's up to you if you want to use this shortcut method. (I did and so far after 1 year no issues. Both my tensioners were cracked, thats on a 2000 100k miles XJR)

 

Sarc - can you recall the torque setting you used for the camshaft cover bolts. I am about to refit the right cam cover which I removed to check if the tesioner had been upgraded. The figure I have is 10 Nm. Is that the torque setting you used.

 

Feels not much but it is sufficient.
10 Nm = 7.5 ft lb = 88.9 in lb (valve cover)

 

At that low a torque, what keeps the bolts from loosening due to vibration - is blue loctite or equivalent used on the threads?

 

You could, but none is called for. It wouldn't hurt anything.

There is tension in the various rubber bits and the bolt underside is riding on plastic, not metal, so that probably helps. Finger tight plus a "smidgin" is about all that has ever been required on just about any valve cover. The trick is to let the seals move and work. Oiling or greasing the gasket is usually helpful in letting the gasket squirm around to get the best seal.

 

Could someone please expand on the "yucky top plastic tensioners". Where are these located and what do they do?

 

The plastic cam chain tensioners are located under the valve covers and are intended to keep the chains tight enough to prevent the chains from jumping the sprocket teeth, getting the exhaust cam out of alignment with the piston operation and destroying the engine.

The plastic versions will very predictably fail.

The link in post #2 of this thread lays it all out.

 

Hello folks,
I was cleaning the TB and egr and dropped a drill bit into the hole on the driver's side breather, pulling it out the drill caught on the hose for the intercooler and just slipped right down into the hole. I was planning on getting to the cam chain tensioners pretty soon so I just kept going, got the valve cover off and got the drill bit out. It would not have presented a problem because the breather has a filter that would prevent the object from ever falling into the top end of the engine. Oh well, now I'm in there.
The link for the tensioners is broken http://www.mediafire.com/?mijhydngtog but it must be around this site somewhere.
I can take some pics of my repair if anyone is interested.