A while back, having left my car sitting for nearly three weeks, I noticed a large patch of oil underneath her. Ooops. I can't tell whether that happened while she was sitting, or after the first drive when getting back. However, I have kept a careful eye on oil levels since, and while there has been a slow decline, it's nothing out of the ordinary. I tried putting cardboard under one night and got a couple of drips, but each time since that I've tried, it's either been too windy or too wet for the cardboard to stay put.

Anyway, today I got some photos of some drips with my tablet, and it seems confusing. It seems to be coming from what I think is the torque converter area. Or perhaps dripping from somewhere higher up. The colour is also odd. Some is darker, but some, on the bolt, looks rather fresh (I added some recently, but not much). I checked transmission fluid early on, although the engine was cold, but I don't think it's that. There was also some oil on the transmission case (? the large pan behind the round thing (torque converter?) behind the sump) that would sometimes form a drip ready to fall, hardly a torrential gush.

It's not a major leak, or at least it doesn't seem to be, but what I find odd is that the puddle could be so large initially, nearly two feet across, and then pretty much nothing. A seal drying out from not being driven and then getting moist enough to seal after a good drive?

Front of car to left in both shots. The first one has the three oily places I spotted with the tablet circled in red.
Any suggestions, hints, etc. would of course be gratefully received.

 

The red is probably trans fluid. If it's coming from the torque converter area it's possibly the front seal of the trans. Did it sit much before you got it? Have you checked the trans fluid?

 

Thanks, Timeisrelative.
I did check the trans fluid, but when the engine was cold--I gather it should be done when it's hot. But it was at the COLD level, so I wouldn't think enough could have leaked out to cause the puddle. And it felt and smelt more oily. Could be both, of course. That would be fun....

 

As said, the red/pinkish oil is trans fluid, and the TH400 is not welcoming of lack of use. It will drain back, as in the torque converter drain back into the pan, overfilling the pan, and leaks will be greater. Its just how it is. Mine all did it, as did the older BW12 units, and once they were returned to daily type use, not a drop.

Trans oil will spread quickly on the ground, so a mere egg cup, will spread out and look really huge.

Engine oil:

Different mongrel on the V12.

It will be up the top somehwere, and running down. That is my findings over the years.

Some common areas:

Oil sender units, both of them, but mainly the smaller idiot light unit.
"D" seals at the rear of each cam block, and the associated cam cover gasket.
The valley cover plate. the one that runs the length of the "V". NOT common really, but the gasket here is just like a tissue paper.
The o/ring seal of the distributor to the "V" plate.
The tappet block to head "seal" has failed. There is NO seal as such here, it is a chemical "seal" on a metal to metal coming together. Greg in France has an excellent write up of sealing this, due to a MAJOR tear down of the engine to reseal them as the factory did. Mostly these leak oil onto the exhaust manifold.
The 2 small (6mm) oil hoses at the oil filter to block area. They leak, run around the pan, and drip off at the tin cover.
The tin oil pan itself. Probably distorted now from Gorilla's overtightening the bolts trying to stop oil leaks, HAHA.
The rubber bung, front A bank side of the timing cover, just below the head gasket line. Well known leaker, and 5 minutes to fix.
Oil cooler hoses. Simply old age.


The list goes on, but they are the more likely suspects. Some easy to fix, some not so.

Proper identification of the EXACT starting point is critical to your wallet.

 

Thanks very much for that detailed write-up, Grant. I have found a couple of hoses that seem oily, and while one of them might be an oil cooler hose, I'm not sure what the other is. I'll get some photos and post them. And I'll give the top area as thorough an inspection as I can.
While it's odd that the trans fluid decided to leak this year and not last year when I also went on holiday, you suggest that as long as she's used frequently, it's not a major worry.
The rubber bung at the front has been replaced very recently, and I was wondering if that was the cause, but the area there seems dry.
This, I assume, is a good place to start looking: Oil Pressure Sender and Switch
Thanks again, Grant. Much appreciated.

 

One more, and 3 coffee's down.

FRESH OILS, and I mean ALL the oils, Engine, trans, diff, steer, brakes.

This keeps the seals/o/rings/whatever nice and pliable.

Many a leak/weep on any of my Jags has responded well to some simple fresh fluid, and that is soooooo cost effective as to be scary.

These cars are mostly "part time" cars, so do not do teh miles/kms, and the fluids are forgotten. Even my stored beasts get ALL fluids changed annually.

 

The easiest way is oil dye and a uv light you'll see where new oil is leaking down. My car has the same issues I drip 1 quart every 8 hrs at hard hwy speed, going to be doing all the top gaskets soon.

In the meantime I determined my camcover half moon seals are some sort of aftermarket blue junk and arevthe source of 90% the problem, I cleaned the area with electrical parts cleaner and foaming fabric cleaner sure enough a 1 hr boot down the highway and back the area was black again.

If you find your back half seals are done I have a spare machined aluminum set I can sell (at cost) as I accidentially ordered 2 sets of two.

 

Thanks for the offer, Van. If I need to, I'd like to take you up on that--I've heard good things about those machined seals. And I'll see about the oil dye idea, too--sounds like a very good tip.

Grant, I think she's fairly well replenished with oils. Might be time for some new ones, though.
Engine: Done every six months, spring and autumn. Coming up for her next one soon.
Trans: Was replaced when the transmission was overhauled, coming up on three years.
Diff: Had a diff oil leak last year, got that fixed, so that should be fairly fresh.
Steering: This one I can't remember offhand. Probably when bought, if not more recently.
Brakes: Not more than three years ago when I had a leaking brake line.

I went out and checked the engine over pretty thoroughly, and got a number of photos, which I shall post here as I don't know which is the most important.
Starting with the most obvious, this shallow pool of oil on top of the V right at the back. I wiped it up after taking these photos, and we'll see if it reappears (I took a drive afterwards to do some shopping, but it's decided to rain so I won't be cracked the bonnet right away).


Another angle:


This makes me wonder if the leak isn't from the cam cover (??) gasket, following the wiring bundle down, and dripping into the V.


The oil stain only goes partway down. Basically, to the V and then drips off?


More oily wiring on the outer side of the B Bank, near the water rail.


This nut also had a fair amount of oil around it.


These next two are also confusing. The first appears to be leaking from the power steering reservoir...? Maybe? It's just a hose damp with oil.


Another hose damp with oil. At least I think it's oil. Very black. My oil, by the way, gets changed twice a year.

 

MMMMMMMM.

What I see:

Oil pooling at the rear is 80% oil light switch related.
The "D" seals appear next, as do teh cam cover gaskets.
The leak near the AAV is either the camcover gaskets, and MAYBE the tappet blocks.
The steer pump hose is the RETURN hose. It is nothing special. I use standard Trans Oil Cooler hose, and memory is 10mm ID?.
The other steer hoses also look like return hoses, and OLD as well. They have a life of approx 5 -7 years IF the fluid is changed annually, as it should be,

My thinking is, remove the top items, Inlet manifold, etc. Replace the cam cover gaskets and the "D" seals.
Replace the smaller of the 2 oil switches.
Replace the oil filler cap seal, probably old and tired now.
Replace the steer return hoses, ALL OF THEM.

I see nothing out of the ordinary, just age related leaks and hoses etc that need attention.

 

Hmm. Thanks very much for the diagnosis, Grant. I think the first thing to do is track down the exact location of the oil light switch--it doesn't appear to be where The Book says it is on Palm's '83. See if that is mucky. And what it takes to replace it.

Then I have some reading to do. Starting HERE and HERE. Palm also insists that "If you have the aluminium half moons, you need to use the gortex gaskets! It’s one or the other: Either OEM rubber half moons with no gasket, or aluminium half moons with gortex gaskets."

What are the "other steer hoses" you refer to? Is what I think might be the oil cooler hose, bottom photo, not an oil cooler hose after all?

 

The oil light switch is basically facing 6A spark plug. Lean over the RH side, look down the rear of the throttle capstan, between that capstan and the fuel rail, there it is.
The snap included is the one on the Red car. The larger one is the gauge unit, and below it, partially hidden is the Toyota idiot light switch.

Alloy updates for the "D" if you wish. I have never used them, OE, with a good coating of Hi-Temp RTV is more than enough.
Just to clear up something. NO matter, OE or alloy for the "D", cam cover gaskets are still needed, and the later 6ltr spec Gortex spec are what you need. There is NO either/or, cam cover gaskets will be needed.

YES, they look like the steer hoses to me.

Quick check. reach down the rear of each camcover, COLD engine please, and wipe your hand on teh "D" seal. If you come out dry, they are OK, but I bet you come out wet and black.

Its simply the age of things, NOT a design fault. Thousands of engines use these "D" seals, and they are replaced periodically, COZ THEY LEAK. OK, most dont need the dismantling the V12 does, but thats the luv affair we have.

The idiot light switch is a simple switch, NOT unique to Jaguar. Mine run Toyota switches, in there. 1/8BSP thread, spade terminal., JOBS DONE.

 

Thanks again, Grant. Noted about the gaskets. So the 6.0 litre ones will fit the facelift 5.3 litre then? Gortex it is.
So the XJS has a power steering cooler? Why else would there be a hose running out from the starboard (right) side of the radiator area, going down? There's a coolant rad, an oil cooler rad, and an aircon rad. I'm just confused.

Anyway, I had another poke around, and discovered a few things.

First off, after about an hour's driving total in suburban traffic, the V remains perfectly dry. In fact it seems cleaner than I had managed to get it before....

The oil pressure sensor stuff, neatly tucked under the Y-shaped tube that does whatever it does, looked quite dry to me as well. (It's not quite in the same place as yours, or at least it's better hidden.)


This is the B Bank rear, and there was liquid oil (about a drop) on top of the wiring bundle, as arrowed.


The B Bank seems distinctly grottier than the A Bank, for what it's worth.

I also managed to grope around the rears of the camcovers, and yes, both half-moon seals left black residue on my fingers. Using a boroscope, I poked around down behind the engine, which is fairly black in parts with muck. Hard to tell what is more than quarter of a century of muck, and what is leaking oil. Photos did not come out at all well.

I checked the power steering fluid levelrecisely at the "Cold" mark. The engine wasn't fully cooled down--still a little bit warm to the touch, but only a very little bit. I assume that's not going to throw the reading too far off.

I think we have the source more or less determined. So thanks again for all your assistance and advice!

 

Confusion clearing time.

3rd beer, beware of spelling issues.

You are RHD, GOOD.

The steer cooler is tucked away under the LH engine mount to cradle bracket. BARELY visible fro above, and not much better from below. In that sanp of yours with the hose at teh steer pump, follow that hose aft, and it will terminate AT the cooler. Then another hose runs from that cooler TO the rack, HOWEVER, that hose becomes a metal pipe at about the oil filter area, give or take a few inches.


THIS is the steer cooler, clearly OUT of the car.
The hose joints AT the cooler do leak, OLD AGE, and new hoses will sort it quickly.

Looking at your recent stuff, I still reckon the MAIN leaks you have are the cam cover gaskets and the "D" seals. Once they are done, and the engine given a good bath, the rest will be simple fixes, IF there are any.

The radiator has a trans cooler in the RH side, and the 2 hoses on your year model will be swaged style, and connect to 2 steel pipes at about the alternator area, and these pipes go down the RH side of the engine (at about sump level) to the transmission.

Then there is the A/C condensor, which sits atop the ENGINE oil cooler. This engine oil cooler has 2 LARGE diameter hoses, and pipes, which sometimes leak, again old age, nothing more sinister.

ALSO

A lot of the "upgrade" gaskets/seals, are the 6ltr stuff, same basic engine in more ways then most realise.

 

Very much appreciated, thanks. I'll re-read that a few more times and look at diagrams, but for what it's worth, I think your diagnosis about the main leak is the correct one. I'll see how fast the V fills with oil again, which should tell me how serious/urgent the problem is.

I suppose leaking tranny fluid is a good thing, as otherwise I'd never have investigated the possibility of an oil leak....

 

Grant,

I am in desperate need to find the "2 small (6mm) oil hoses at the oil filter to block area" and the "rubber bung, front A bank side of the timing cover".

I have had an oil leak since I got my '91 Coupe (no big surprise - someone, maybe even you, welcomed me to the group and advised that she would be "marking her territory" commencing immediately!!). Last night I wiped everything down underneath (it was a real mess!!) and then went for a short drive. I clearly have a leak at the front and at the rear, but I've ruled out the "D" seals and the oil pressure sending and warning switches. See the attached pics.

What do I have to remove to get to the 6mm oil hoses? Presumably I can't have to move much to replace the aforementioned bung, becuase you say it's a 5 minute fix, and I can't even check the oil and water in 5 minutes on this thing (don't get me wrong - I absolutely *LOVE* my XJS. This has been on my "list" for a long long time....)



Fresh oil (not transmission fluid) on the bottom of the torque converter....



Fresh oil dripping from oil filter (and yes, it's on good and tight....)



Fresh oil dripping off of the front of the engine (A bank side...)




Fresh oil dripping off of the lower radiator hose (B bank side)

 

bknorwood,

If you go to the Jaguar parts website and select engine, then go to the timing cover section and you'll see the bung and its position.

Cheers

Paul

 

Thanks to VancouverXJ6, I now have some machined aluminium half-moon seals ready to go into the car. They're rather smaller than I expected, no more than 2 cm across. And they were very tightly packed in an old cotton glove wrapped thoroughly with duct tape. I believe that with these and the Gore-Tex gaskets, and a bit of gasket maker around the arc and nowhere else, they should prevent leaks until the heat death of the universe....



Now I have the half-moons, as well as all these new gaskets, the oil leak might be tamed. It's not fast--in six weeks, the oil level is now down to about 1/4 up the "Normal" zone, from being a bit high right after the oil change. But it's faster than I like.


Also, the valve cover seals are definitely the new Gore-Tex over metal ones. As my nice macro lens makes clear:

Metal sandwiched between black stuff which I assume must be Gore-Tex, not that I am really sure what Gore-Tex is....

The only question remaining is, what is this about the "triangular thread" bolts? Is this applicable to facelift cars as well? And, even though the car's running very well these days, is there anything that ought to be checked while the valve covers and all that are off? Okay, two--no, three (technically)--questions, but this isn't the Spanish Inquisition....

 

The cam cover bolts are NOT round, they look like a triangle when viewed end on.

Never had an issue with them, ever. Some have, no iea what or why.

Over-tightening maybe to try and stop an oil leak, rather silly exercise to me.

Mine all went back in, wth Anti-seize compound on the threads, and that was in 1996,and still OK today, as are all the other V12's I have done.

Trick with the Goretex, is a VERY smooth surface, NO nicks, or gouges. If you find any of those, a SMALL dressing of Hi-Temp RTV in that imperfection will aid sealing. My PreHE was a shocker, must have been an angry Wombat that attacked it, so a dressing of RTV, and the Goretex gaskets, oil tight, in that area at least. It weeps from the tappet blocks, and at 640000kms, I an not brave enough to open that engine up,.

If its running fine, do not re-invent the wheel. Do the gaskets, drive the thing. There is nothing to mess with in there without going DEEP into things that are perfectly OK.

 

Thanks as usual, Grant. Nice to know I don't need to worry too much about the bolts. (Triangular bolts? Presumably the thread section can't be triangular, or else how would they screw on?)

Doubt it was a wombat that attacked yours. Harmless cuddly things. Probably a drop bear. Gotta watch out for those--that's why convertibles aren't popular in Oz.

640,000 km.... I have a way to go yet. Mind you, a return trip to the Moon would get me there....

 

HAHAHA,

Wombat the marsupial is a nasty little sucker when cornered, like most of us I suppose. Solid as a Brick Outhouse. Hit one years ago with the Road Train, bent the front axle, and the &&astard walked away.

Wombat the "fiddler" is the expert that reeks havoc.

Love the thought of triangle threads, that spilt the beer, good on ya.