So my DD Xj has developed a leak. ( Imagine that). The odd thing is we're it's leaking from.

It seems like like all the oil originates from behind the starter and then puddles and runs down from there. It's dry able. The starter so I don't think it's a head gasket or VC. Initially I was thinking rear main but looking in the bell housing you would think there would be more oil in and about the converter than there is.

Looking at a parts diagram it looks like the the rear main has a adapter or housing that bolts to the back of the block and there might be a gasket there and it's flinging it into the starter nose and then it runs down the block.

Any thoughts ? Or pictures of the rear main and adapter area.

 

Hi Jeh,

Two other possibilities are the cam cover gasket, particularly the two half-moon sealing plugs at the firewall end that seal the recesses left after machining the camshaft beds (Part 7 in the diagram below):



And also the gasket for the rear cover of the cylinder head at the firewall end, Part 11 in this diagram:



It is possible that oil leaking from those areas can leak down around the bellhousing and then drip off the bottom of the belhousing. I once suspected our rear main seal of leaking but discovered the oil was actually coming from the cam cover seal near the rear end of the head. I hope it's that simple for you. I actually purchased the rear seal assuming I was going to have to pull the transmission and do the replacement, but it turned out I didn't have to. If you discover you really do need the rear main seal, I'll be happy to send you the one I purchased (if I can find it!).

Cheers,

Don

 

I ended up steaming it off and getting it back on the lift and its looking like the head gasket.
Its at the extreme rear of the head by #6 inlet port.

Though looking at your 2nd picture its entirely possible its the gasket 11. its just so hard to see with all the stuff in the way. Is that gasket serviceable without taking the head off? And by chance you have a part number? I see its included in a head gasket set but I haven't found it by itself.

Thanks

 

A small inspection mirror with an adjustable angle and a bright light may help you identify the source of the leak. It may also help if you can figure out a way to move the engine away from the firewall as much as possible. Parking the car downhill or raising the rear end might help. Maybe also loosening the screws/bolts for the subframe Vee mounts?

The part number for that rear cover gasket is EBC2568, per jaguarclassicparts.com (it's on the diagram for the "Cylinder Head Less Valves - 4.0 Litre").

Searching that part number at jaguarmerriamparts.com, they show the gasket as available at $11.21.

I have only replaced that gasket while the head was on the bench. With the head in place, access would certainly be tight, but it should be possible to remove the cover and replace the gasket with the head in situ. A ratcheting box-end wrench/ring spanner would probably help a lot. You'd want to remove the cam cover and displace as many other obstructions as possible (maybe the EGR pipe?), and use whatever method you can figure out to move the engine forward away from the firewall.

Cheers,

Don

 

Thanks for the part numbers Don.

I went out and took a look again this am and that gasket looks pretty tight. I've looked with a mirror and a boroscopebut just couldn't get the right angle.

I will try again on Monday but I have a gut feeling it's going to be the head gasket. All in all it doesn't look like a bad job to do and I know it needs valve seals so maybe just suck it up and do it.

I saw conflicting info on the head bolts one source said you must replace another said check them. My experience has been if the engine hasn't been overheated you can usually get away with using the old ones again.

Any thoughts

 

The head gasket job isn't terribly difficult but it does take some time, and there are several other jobs you'll want to also do while the head is off, including the valve seals, checking the valve clearances and correcting them if needed, replacing the heater water control valve and oil pressure sender, cleaning and sealing all the common left side oil leak points, replacing the upper timing chain tensioner, etc.. So personally, I would want to confirm for certain that the oil leak is at the head gasket and not one of the easier-to-replace spots like the cam cover and rear head cover. I can't personally recall an XJ40 cylinder head gasket leaking oil at the rear of the head. Usually it leaks oil above the distributor or the aluminum head erodes between a coolant jacket and a combustion chamber creating the huge cloud of white smoke from the exhaust and rough running. Perhaps other members will chime in if they've had a head gasket fail at the rear end of the head.

Search the TSBs because I don't want to rely on my memory, but what I recall is that, initially, Jaguar stated that the head bolts must be replaced every time because they are tightened by the torque-to-yield method, where you torque them, then turn them some additional amount (90 degrees?). During that additional twist, the bolts actually stretch. But I believe Jaguar later revised its instructions and stated that the bolts could be reused once assuming they were not damaged. It's been a few years since I did a head gasket so please don't rely on my memory.

Cheers,

Don

 

Hi Don

The Cam cover and seals where done about a year ago, so maybe that rear cover is worth another look. For under $20 and maybe an hour or so vs $$3-$400 and a good 10-12 hours its worth another look with a boroscope and some brake clean.

Thanks for the input.

 

Oddly enough I took another look when it was darker with my Boroscope and did see the leak was coming from the intake 1/2 moon on the V/C gasket.

Ordered and installed another and boom, the Hazmat cleanup crew stopped following me around.
Im not sure what happened as the gasket was only 1 1/2 years old.

 

Hi Jeh,

I'm glad you tracked it down without having to remove the cylinder head!

I have not personally had this problem, but I recall at least one other member having a problem with a cam cover gasket set not lasting long, and his conclusion was that he had used and aftermarket set and was going to use an OE set to replace it. But I've always used aftermarket sets and they have typically lasted, I would say, about 5 years.

I don't know why some gasket sets seem to fail prematurely. Have the temperatures in New Mexico been unusually high over the past year and a half, or have you driven a lot more miles than in the past?

I wonder if carboned up valves that aren't sealing completely could be allowing combustion chamber pressure to escape up the valve stem and into the cam cover, forcing oil to escape past the gaskets? I tend to doubt it. I've done the head gasket job three times, once on our '88 and now twice on our '93, and the valves were not badly carboned, though they did benefit from being lapped. I doubt you have to worry about that. Sorry I mentioned it.

Cheers,

Don