I've now had my spark plug well gaskets changed twice. Initially it was a small amount of oil in the spark plug in the number 3 spark plug well. My mechanic changed the spark plug gaskets as well as the cam covers. 2 months later I get this acrid oil burning smell and I didn't know where it was coming from until I lifted up the cover for the spark plugs. I found that there was oil seeping around the 4th plug well and leaking around the cover and dripping on the exhaust manifold. So, I called up my mechanic and he took a look. He replaced the gaskets under warranty. Now just two weeks later I get smell again. I haven't checked it yet because it's been raining. But I have a high suspicion that it is leaking again. Does anyone know why that might be happening so quickly?
Thanks for any advice here. I'm sure my mechanic is not going to be happy to have to replace it again under warranty.

 

The cam covers are plastic. Maybe they are warped? Never heard of it just guessing.

Whenever I change spark plug well gaskets I apply a thin layer of silicone sealer just because of the problems you are having. I put a thin layer on both sides.

Jaguar must install them pretty good because I am at 94K miles on my 2005 STR and they are still fine.
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Maybe your guy is tightening them too much in a reflexive attempt to prevent leaks.

Mine are the factory original, reused after opening for a tensioner change and no leaks.

I oil all the rubber surfaces and tighten lightly ... just over finger tight with a nut driver, not a ratchet.

 

To add my $0.02 on this:

Good points noted above.

I also use a very thin layer of RTV sealant on the bottom side of the spark well gaskets (that come in contact w/ the cylinder head.

I have also used a bead of RTV sealant on the lower rear corner of both cam gaskets for extra insurance.

Over tightening the cam covers will wreak havoc over time.

Did the mechanic use Jaguar OEM parts or aftermarket gaskets? Hope these pointers help, thanks

 

I'm afraid I still have leaks and they must becoming from the cam covers now. I had my mechanic replace them under warranty one time before as it was still leaking in the spark plug wells then dripping to the back of cam cover where the spark plug wires come through the back. I still smelled burning oil and checked the spark plug wells, which now are clean and not leaking so I'm assuming it it's actually leaking from the cam covers in the back. My mechanic uses OEM Jaguar parts and will be checking the cam covers to see if they are warped and will be changing the gaskets again. If they are warped, I'll have him put RTV sealant on and hopefully that solves it for good. Though he says that I shouldn't need it with OEM Jaguar gaskets.

 

The gaskets need a dab of sealant at the corners where the casing joints are.

 

Make sure that he removes all of the old gasket material and cleans the valve covers. I've seen people try to do this and leave residual gasket material in the grooves, never sealing since they won't sit level.


This is actually a pretty good sealing system. Do the following:


1.) Remove valve cover and remove all gasket material, including the solenoid seals.
2.) Run small screwdriver along groove and remove any residual material.
3.) Wash valve cover in hot soap/water, dry with paper shop towel.
4.) Install new valve cover gaskets in groove, making sure that they are fully seated and make sure that the rectangular bosses face down, against the head.
5.) Use razor blade to trim old RTV flush with the head surface.
6.) Wipe head surface and gasket surfaces with brake cleaner.
7.) Install new solenoid seals with the wide surface down, toward the head. Make sure they fit nice in the round hole.
8.) Put 6 dabs of black RTV on the surfaces of the head where there is a seam - two at front where the front cover mates and four in the rear with the half-moon cam plug fits.
9.) Wait 10 minutes.
10.) Install valve cover, snugging the valve cover evenly but not "tight". Make sure you install the new o-ring type seals on the valve cover bolts.


It will not leak if done properly.

 

From my experience, the aftermarket gaskets do not do as good a job sealing the cam covers on the 4.0 Litre as do the original Ford or Jaguar gaskets. After several attempts with aftermarket gaskets/seals, which ended up leaking after a very short time, I replaced them with the OEM parts and have not had any additional issues with leaks of any kind.

If you use the factory gaskets, you only need to put sealer at the points where the timing case meets the cylinder heads and torque the bolts evenly.

 

Disagree. Then why did the factory put black RTV at the half moons of the cams?

 

Can you post a photo of the 'half moons' on the 4.0 Litre V8 heads? I never recall seeing them on any engine I worked on and could have somehow missed them.

 

Norri, I know this post is about 4.0, but could you tell me what exactly valve cover caps are on a 3.0?

"Apply a 5mm diameter bead of silicone gasket sealant on the valve cover caps and apply an 8mm diameter on the two places where the cylinder head and front cover join."

Interestingly, the procedure for 4.0 is without this:

"Apply RTV sealant WSS-M4G320-A3 to two places on the joint between the front of the valve cover and the cylinder head.The application of sealant must be 3mm diameter by 12mm long. Install the valve cover immediately after applying the sealant.The cover should be fitted directly to the head without smearing the sealant or the seals."

 

Go ahead and put them together as you wish. Enjoy the oil smell when they leak again. I've been through this before and am simply trying to save you time. However, I'm sure that my experience means nothing.


Please carry on and thank you.

 

What exactly is your 'experience'? If you have any experience working on a 4.0 Litre engine you would know they do not have 'half moons' while the 3.0 Litre V6 does at the back of the heads.

There are many forum members looking for accurate information to help them with repairing their vehicles for the least amount of money and to save time. The original poster on this thread has a 4.0 Litre engine and is requesting help for that particular engine. Random and impertinent comments are not at all helpful and can be confusing.