Oil leak repair cost estimate

I have a 1991 xjs v12, 5.3 jag. I’ve returned it several times to resolve and oil leak with no success. The mechanic returned it to me twice stating the leak was repaired
when obviously it isn’t. He states the oil is coming from the CAM CARRIER TO THE CYLINDER HEAD and needs to be resealed while stating there is no gasket between the two parts. Due to the long standing issue, I will undoubtedly need to take it to another mechanic who are scarce for my area. I also took it to another jag mechanic who appeared skiddish aoutg

This is a continuation of my earlier comment which went haywire.
My question is, anyone have an approximate estimate of the cost to repair the oil leak?

Is it the half moon seal ? I’d like some clarification here. Are you talking about the cam cover?

No. The cam carrier is separate from the head, and uses sealant to seal it to the head, no gasket.

Theres a ton of work involved to reseal it. The cams have to come out before you can remove and reseal the carrier, which means disengaging the chain tensioner, taking off the cam drive gears, etc, etc.

I’d make certain the half moons, the cam feed banjo bolt seals, and the valve cover gaskets are absolutely not the culprit(s) before tacking that job.



Thx much Jon. I also concluded this must a big job, which is why the mechanic who rebuilt my motor hasn’t

performed the repair after making the diagnosis and telling me he would have to “pull half the engine apart.”.

The info you provided confirms my suspicion.

I can only state the info provided me by the mechanic which I attempted to provide using his wording verbatim.

“Oil is coming from the cam carrier to the cylinder head and I will take them apart and use a gasket sealer

to stop the oil leak.”

What IS a “cam carrier”, and do we have them on our 4.0s? If so, might be the source of my major oil leak … :thinking:

It’s a separate component, bolted to the head, that holds the camshaft and tappets on the V12 engine. The 6 cylinder doesnt have a separate piece like it.


As Jon said make sure it’s not the half moons, cam feed banjo bolt seals, or the valve cover gasket.
Give the engine a wash, drive it and examine.

How long ago did he rebuilt the motor?
Wouldn’t he be responsible?

He is responsible and as such will be taken to small claims because ‘HE HAS DIAGNOSED THE PROBLEM”, yet fail on numerous occasions to

perform the repairs even after telling me what work is involved. Apparently, he wants the warranty period to expire.

IF the heads were removed and rebuilt, then you would remove the tappet block from the head to reseal it to the head with a more modern sealant than Jag used originally. Some of the gas additives affected the sealant Jag used originally. That is easy at that point but a nightmare to do at this point.
Completely fixing all leaks on an XJS would require teardown equivalent to a rebuild and that is unjustifiable if paying shop prices. The last XJS total rebuild we did was $14K 20 years ago so you can see the only total rebuilds are being done on E-Types.
Was there some repair done that was supposed to fix this leak and now it is still leaking?

The engine was rebuilt in 2022. The oil leak was present after the rebuild. It was taken back twice

And I was told the issue was resolved. Each time I returned it. He diagnosed the

problem in 2023.

The term rebuild can cover a wide range of work but pretty much has to mean a valve job was done.That means the tappet blocks would have been removed from the heads and been resealed when they were reinstalled. If that is now the source of the leak, then that should be covered under warranty for the warranty period. I hope you have paperwork showing the leak being reported during the warranty period. Realistically, modern sealants should be good for decades. A shop that adjusts valves would likely send just the heads to the machine shop. If they were relying on the machine shop to adjust the valves, then the machine shop would have to install the tappet blocks and the cams in order to adjust the valves.
I don’t see it but for some reason I was thinking you are in California, where the BAR helps with these problems. If you want to send me a copy of the Estimate and Repair Order, I’ll be happy to give you a general opinion. I don’t know if you can attach it in messages but you can email it directly to Greg@JagUSA.com

It sounds like the mating surfaces may no longer be flat, if so, sealant is unlikely to work.
The cam carrier needs stripping off, check both surfaces for flatness, possibly machining flat, then resealing.
Not sure if the Jag engines have a recess built in for the sealant to push into and act as a gasket/O ring.

Does this seem highly probable ( surfaces no longer flat) after a complete rebuild?

Just curios Greg……are you a jag mechanic as you appear XJS knowledgable ? If so, possibly

I plan to use your comments during

my small claims court action. I spent Friday checking local jag mechanics and as I assumed,

none except one works on the xjs, which I already ascertained. I ask the one mechanic who has done work

recently if he might consider performing the task ,but he appeared hesitant as he had already stated it is

a big job and he works alone.

Again, thx.

It’s a gasket less metal to metal joint, so any distortion and it is unlikely to seal.
If the head has warped at all, the upper surface will need machining, and the lower surface of the cam box will need checking.

There is a reason the sealant isn’t working. Maybe it’s that the mechanic isn’t allowing enough time for the sealant to solidify somewhat before final clamping, but maybe the two surfaces are no longer flat enough.

If, for whatever reason (example overheating) The head or cam carrier became slightly warped, then no mechanic would be able to fix any associated oil leak without sending the affected parts to a machine shop prior to assembly. In fairness to the average mechanic, a straight edge test for head or cam carrier straightness is not something that they would normally do. So he might have in good conscience, replaced the gaskets and considered the problem solved.

I’m afraid your responses are coming from people who are also not familiar with that motor.
A warped head would cause you problems with the cam running in their journals that are not straight. If the head was in a curve and then surfaced on the head gasket surface, you will have other problems but the head to tappet block would still not leak if resealed properly.
The tappet block would simply match the shape of the head when the fasteners were tightened. #9 in the attachment. You need to determine IF that is the source of the leak, which means a clean engine and then checking the source of the leak.
My shop is no longer open to the public but the mechanics that are still working have rebuilt many Jaguar V-12s so I could write you a generic estimate to reseal the tappet blocks but that doesn’t help until you are sure of the problem.
I’m expert witness on a number of Jaguar restoration law suits but that isn’t justified with damage in between the $5-12K limit of small claims and $200K where you can justify attorney and expert witness fees. Even then, it is a bit of a joke.
XJS_TappetBlock.pdf (68.0 KB)

Seems you might be correct as most aren’t familiar with that auto/engine as it’s a bit more complex and takes

someone familiar with that particular model. I know this because I’ve been through hell over the years and spent too much. But

“if you dance to the music, you must pay to the piper.”

The mechanic who initially rebuilt the engine wrote this statement to me was: “it appears the oil is coming from the cam carrier to the cylinder head

and I will have to go ahead and reseal those now. There is no gasket between those two parts and so I need to take them apart and use the gasket sealer to stop the leak that’s gonna take a little bit of time and I have to pull half the engine apart again.”

I took the car back twice to resolve the problem and on each occasion, he stated the problem was fixed. This was after his above aforementioned statement.

I “assumed” his written statement contained sufficient information to deduce the problem if presented to a knowledgeable jag mechanic familiar with that engine.

I recently had the transmission rebuilt which was also part of his rebuild. That will also a part of my small claims suit. Obviously with seeing and examining

the car, you cannot be totally sure of the issue, but I can only assume your knowledge allows close speculation based on his written statement.

If after reading this, you feel you can present a generic estimate, we can discuss your cost.

Much appreciated.

That sounds reasonable. If you are taking him to small claims, then an estimate for the work he says is needed might help. An estimate from a shop no longer open to the public and not having seen the car might be discarded pretty quickly by a Small Claims Commissioner. Most of them are attorneys filling in and can be very erratic in their rulings, frequently just making a compromise between the two parties when the issue is complex.
I can’t get past the fact that any valve job should have had the tappet block sealed properly to the head. If they weren’t removed, that is a scary thought. That was why I suggested that you email me a copy of the original engine work to look for clues.
Another point, removing enough to reseal the tappet block is a large job but still far less than removing the engine and doing a proper overhaul.