My mechanic and I have been chasing a bad oil leak from the engine and would welcome some leads from here. We have tracked down oil leaks from the following areas, and replaced
(a) the oil cooler bypass O-rings (CAC5118), although my XJR does not have the oil cooler fitted;
(b) the cam cover gasket (NBC2525AA) where oil was leaking from the rear end of the cam cover;
(c) the engine rear cover seal (EAC2911).

BUT they did not completely cure the oil leak problem. The leak is from the left side of the engine above starter flowing downstream and dripping whenever engine is running, and leave a pool of oil on the floor the next morning if stationary. The symptoms are similar to those as previously described by forum members TopHatChef and 95Leaper in their respective threads Oil leak issue, and Huge oil leak/weap.

I found an almost identical complaint entitled "X300 Oil Leak" in the UK forum, and shall let his description explain mine :
"….It has developed a bad oil leak which has me puzzled. Its coming from the back of the engine, where the gearbox and engine join, just by the starter motor. It is definitely engine oil and not auto trans…..there is a constant drip of oil with the engine running, hence it only took a short time to find where the leak was coming from. That is the problem, it effectively makes the car undriveable as it leaves a big oil puddle where ever it goes……The oil leak was coming from the end of the main oil gallery. It is usually sealed with a metal plug with an O-ring, but the O-ring had become brittle and broken up, hence the oil leak. The fix was a 40p O-ring, but to get to it the gearbox and torque converter, plus the sandwich plate and flywheel had to come out. In the end I got an independent specialist to do it, didn't want to risk trying all that on axle stands….."

There is another write-up on the web possibly about the same issue, Oil leaks near filter (XJR) from “The AJ16 Engine”
"An oil leak which looks to be coming from below the oil filter housing might be from the bypass pipe which is the little half do-nut thingy below the filter housing. A single, central nut allows the pipe to be removed (kind of a U bend pipe) and you will see clearly an O ring on each end. These degrade over the years probably with heat etc and it's a simple case of replacing them. don't use EPDM rubber rings, only nitrile, preferably viton. I think this is the number KSH119530. You don't need to drain the sump although there will be a little oil spillage. The other path is to remove the "sandwich" of the adapter. One new gasket and 4 shorter bolts and you can eliminate the o-rings permanently."

Am wondering what O-ring are they all talking about. My XJR does not have the oil cooler fitted, and hence do not have O-ring KSH119530, but have already replaced the 4 O-rings CAC5118.

My mechanic and I are both hesitating whether to remove the gearbox from the engine to find and fix the leak. If there is an anatomy of the engine block with the manual gearbox, it would definitely help. Thoughts? Suggestions?

 

" Catch Can " option not to be returned back to engine oil system ? Never heard of it in this application

 

There is a plate on the rear of the cylinder head that has a gasket this covers both water and oil could this be the source of the leak?
Item 3.

https://www.google.co.nz/search?q=aj...YjnH-7wJASBYM:

 

Item # 4 ? Jaguar # EBC2568 . Can a ratchet wrench get on it as is a tight space

Jaguar GASKET FOR BLANKING PLATE ON REAR OF CYLINDER HEAD - EBC2568

https://www.jaguarclassicparts.com/u...4-0-litre-aj16

 

Thanks Robman25 and Parker. No, this has been dealt with in (c) of my Post #1 above. No more leak from there. The leak is a more serious one like bleeding from somewhere above the joining place between and engine and the gearbox sandwich plate, and near the starter, a mysterious spot beyond access and visibility.

 

Found TSB 03-2-03 on Engine Crankcase Oil Leak but it only applies to the XJ12 engine. The TSB describes "oil leak at the oil pan gasket or at the baffle tray and sandwich plate bolts", and advises removal and thorough cleaning of the oil pan, sandwich plate, bolts and replacing the gasket and applying Loctite Primer to the bolt head threads and Loctite 545 to the sandwich plate and baffle tray bolts. Wonder if the AJI6 engine has similar set up and problem.

But don't let me misguide you with this TSB. Wonder if there is any other possibilities which I have not covered. Background is the original oil leak led me to identifying leak from the oil cooler bypass, then the cam cover gasket and the engine rear plate. The leak is definitely not from the crankshaft seal, but higher above where it is unknown territory. A possible suspect is a blown head gasket.... but car has not shown any symptoms other than oil on the floor. Car has done 180,000 km. Just spent hours fixing the engine noise by overhauling the supercharger (bearings, gasket, oil, belt...). Noise is gone, but oil leak continues, something like "operation successful, but patient died". Sigh...

 

Did the D's on the aft section of the valve cover gasket fall out of position or not be aided with the use of a high temp sealant in the corner of the D's ? You can feel the D's with your finger as you slide it back there .

 

 

Update: It is so nice to work with a mechanic who never gives up. Unconvinced that he could not locate the leak, my mechanic washed out all the leaked oil and let the car stand for a night and then raised the car, started the engine and then carefully observed underneath to catch sight of the first stream of running oil. Bingo! Apparently there is an oil passage running from the oil pressure sensor to the back of the engine where it meets the gearbox housing, near the starter. Oil was running down from the junction of the engine housing and the gearbox, implicating that some sort of oil seal or O-ring inside the oil passage has given up. See pictures taken from below the left side of the engine.




Am wondering which part of the parts diagram is relevant to find the right replacement seal or O-ring.

Also, since access is only possible by removing the gearbox this would be a major operation where the opportunity should be taken to consider also replacing other parts otherwise difficult to reach or would not justify removing the gearbox again. The clutch kit is only 3 years old, and was largely unused until recently.

 

I have no personal experience of this but my best guess is this diagram. https://www.jaguarclassicparts.com/u...-3-2-4-0-litre See, Part 9 and 10 (Plug and O Ring). Although this shows the front of the engine, it also states that 5 of the O rings are required for the vehicle. So it's a fair assumption that the same plug and O ring are also at the back of the engine on the far end of the oil gallery (It makes sense from a manufacturing point of view also).

 

Bugger, if I had known we were talking about a MANUAL car I would have refused to suggest any repairs, just joking envious as hell
would love a manual

 

The diagram seems largely showing the back of the engine, as I imagine the far left is the sandwich plate between the engine and the gearbox? Anyhow, I imagine that there is a similar plug and O-ring at the other end of the engine? Hopefully I don't have to find where the other three are. In my recent thread replacing the O-rings inside the oil cooler bypass, I asked if the O-rings are sold in sets of five each, where would the fifth one go (only 4 were needed), Grant joked about the fifth one being spare as Jaguar Classic Parts is being considerate to save us looking for any O-ring falling and rolling away....

 

Auto and manual XJRs share the same engine . Perhaps a good lesson to be learned for anyone trying to convert from auto to manual that during the conversion project, do not overlook the need to replace all seals, plugs and O-rings in otherwise hidden places as they will come back to haunt you when any of them fail. For me, assuming that this oil plug and O-ring in the diagram are indeed the culprit of the dreadful oil leak, they can't be reached without removing the gearbox. The only consolation, my mechanic utters, is that a manual gearbox is easier to remove than an auto one, primarily due to size and weight.

 

I have an engine out of the car if you need more photos of the area.

 

Even with the gearbox out, access is going to be very tight working around the front suspension. This is how it looks with the suspension removed:



If you need to drop the rear of the engine, the radiator shroud and preferably the radiator has to come out to avoid damage.

Graham

 

@QVHK
"The diagram seems largely showing the back of the engine, as I imagine the far left is the sandwich plate between the engine and the gearbox?"


No I think it's showing the front of the engine. The plate you refer to is the timing cover.

 

Thanks, would like to have the photos of that area so my mechanic knows what else needs to be removed to gain access. At present, he figures that the exhaust pipes and gearbox have to give way. Also is there just one oil plug and O-ring on the back side of the engine, or there is another one in front as per b1mcp's advice?

 

Thanks for the picture. My head starts spinning learning that there is so much to remove just to get to the toasted O-ring(s). Hope there is only one at the rear of the engine, not both ends.

 

The part circled in the first photo is the sender for the oil pressure gauge, that should be replaceable from underneath. I didn't see anything on my engine that would leak in the area circled in the second photo. I didn't pull the starter either.

I can do that when it warms up a bit, it's -23C outside and I've cranked up the heat in the garage.

 

Not quite! They come in packs of 5, that's the minimum order quantity, but price is per each.