First start up front oil seal conversion fail

Hi All,

Some input please.

I decided this was best in the XK forum as much of the detail will be early 120 specific.

1950 XK120 OTS RHD.
Rebuilt engine, gearbox etc all on chassis, body still off. Decided best to check for any problems now rather than after body on. Engine was rebuilt about 5 years ago.
First start up last week and went particularly well, plugs out - good cranking oil pressure 10psi, then when live. 4-5 cranks then fired. Another couple and she was up and running - purring nicely. Ran it for about 4-5 minutes, constant checks, no leaks, 60psi, hisser cut out as it should and settled into a nice idle. Ran it through all forward gears - all good - job done for the time being. Very happy - beer time.
Then I noticed BLACK oil running down the front of my nice clean sump and dripping on the floor. WTF? Checked dipstick - yes, nice and golden.
Seems my expensive front oil seal conversion has failed! It appears like the black seal material has partially disintegrated, leaked, and soiled the oil on the way out. Left it to cool and contemplated whats happened overnight.
Maybe in denial, hoping it was just"seating in" I started it up again the next day. Ran it for another 5 minutes for same result.
At the time of engine rebuild, I recall polishing the distance piece with a buffing wheel, no nicks or scratches, but maybe not good enough and also “end for ending” it so it would have a fresh sealing surface - The black material has me stumped.
SO, I’ve come to the realisation that the front seal will need replacing…
I’ve ordered another one at great expense, and am looking for some input on whether I can replace without removing engine mount/water pump/timing cover etc as they have sealed beautifully. Also it has the early front engine mount which will be a major PITA as I will have to support the engine another way.
My plan is…
-drain oil/coolant
-remove radiator(again!)
-remove flywheel
-remove sump
-remove distance piece
-wrangle old seal out
-hopefully, get new seal in with RTV, replace NEW distance piece

Your thoughts on the failure and also whether I will be able to get the new seal in without disassembling most of the engine again would be most appreciated. Has anyone done this successfully on an early engine?

First photo is current, second is assembly about 5 years ago.

Many thanks…Dave.

I can’t but help think that replacing the seal without having removed the timing cover would at the very least line you up for another failure.

If you have enough room to slide the distance piece back in after having seated the seal in the still fitted timing cover I would be afraid there wouldn’t be enough contact for a good seal.


I’m not at this stage of my rebuild but just a thought. Does the spacer require sealant on the shaft so that oil does not seep between the shaft and spacer.


Thanks to the Skippy contingent and… “Lest We Forget”.

First a correction - NOT flywheel - but damper.

Both raise some interesting points.
The distance piece should definately slide in, but originally did put seal in timing cover first. RTV would have set, then sump at some time later. Maybe not centred? but unlikely? Interesting point re oil between crank and distance piece-hadn’t thought of that. Black oil - still leads me to think poor seal material, but before I tear the whole thing down again, I might do some more homework and running time. I’m thinking It won’t be possible to replace without major surgery as the timing cover housing is very tight.


Hi Dave…this may help you Teflon Crank Seal

And this diagram…showing o ring if you used this type

1 Like

I’m shortly about to do the same thing myself. I’m on my second modern lip-type front oil seal - they both leaked.
I decided to buy a more rigid seal with a metal surround which hopefully won’t have the tendency to deform when fitting. Also acquired a newer-design spacer with an O-ring on the inner surface to prevent another potential path of oil leakage.
On a 120 timing cover the seal won’t fit in the groove without some machining, so my spare cover is away having that done at the moment. You want just enough clearance so the seal can find its own centre in a bed of mastic before it sets. I’m hoping the groove in the sump won’t need machining as well, but I’ll find out when it’s off.
Mine also has the early mounts, so I’ve been scratching my head about how to support the engine while all this is going on. I think an engine hoist with a rope sling under the inlet and exhaust manifolds might be the way to go…?
It will be necessary to have a clear plan of action so everything can be buttoned up before the mastic sets - timing cover, sump, gaskets, etc. Quite tricky.
Oh yes, the advice is to delete the oil slinger, as you want oil to reach the lip for lubrication.


You may want to have a look here at post 65 a video from Payen teflon seal suppliers showing that absolute cleanliness is required when installing to prevent oil leaks and some other important install requirements…Steve Front Crank Seal Fitting Tips Please - Page 4 - The 'E' Type Forum

Steve, thanks for your comments. I had researched the teflon seal in some detail and concluded it may have been problematic/not fit in my application and went for the modern lip seal (maybe should have kept the rope). The distance piece in the diagram also doesn’t seem to align top to bottom, but I get the idea. I also note it includes an O ring between the crankshaft and (modified?) distance piece. If this is my issue then easily solved. Will pursue this prior to engine tear down.

That distance piece with o ring is from the XJ 6 Series 3 and the earlier ones seal on the faces instead of on the shaft. A little bit of sealant of the faces is all the earlier style needs. The space for the woodruff key has just been turned to simplify the part in the newer version.

Chris, thanks for your reply. Two failures!! We’re both doing it wrong? I just ordered an new more rigid surround seal with new distance piece from one of the big UK suppliers. It will be circa $200AUD when I get it. I’m seriously considering re-installing a rope seal. I have an engine lifting bracket so it can be supported from overhead but prefer not to have to re-visit this. I will keep you and the forum updated if I can find an “easy” solution.

Thanks David, I think I can seal the distance piece to shaft without major surgery, but still worried about the black oil. Will keep you posted.

The distance pieces interchange if you’re wondering and they send you a newer one, the only advantage of the old style is that you can flip it around once to get a new running surface.

You will likely have to cut the new rope contrary to some instructions and you can use the crankshaft as a fitting tool. I imagine it is not easy with the engine installed but it can certainly be done. Good luck!

Hi Dave:

Did you check the archives on the Forum because there was some fairly extensive discussion of this issue a little while ago. If memory serves, two listers discussed fitting the newer lip seals, although possibly on later cars (Tom and Nick?). For what it is worth, following a rebuild of my engine ('53 120) and experiencing a front seal leak (rope seal) and on the advice of a well-known Jaguar man I dropped the sump and replaced the lower half with the later E-type rope seal that has a wire through the centre. This seemed to do the trick as following a good run I never see more than a slight film of oil sweat on the front of the sump never amounting to enough to form a run or drip.

I do recall reading many years ago in Jaguar Driver magazine of someone drilling out the timing cover around the top half of the seal in order to remove it with out lifting the cylinder head as one would otherwise have to do. Seemed a tad fraught with scarf issues I thought at the time!


Hi Dave and Chris,
Yes we have discussed this on the forum recently, particularly the details of the later and preferred distance piece on which the lip seal rides. The retrofit lip seal supplied by all the regulars has a metal outer casing and may or may not fit properly in the groove. Mine required a small bit of machining. The concept of the retrofit is to bed the seal in an oil resistant sealant, both in the timing cover and the sump, at the time of installation, so as to allow it to center itself. My sump did not require any additional machining, but needs to be checked.

Steve H has described the O-ring seal of the new style distance piece, closing off the oil path through the space between it and the crankshaft end. Very important.

Regarding going back to a rope seal, that will guarantee a continuous leak on the front of your engine, I would not recommend that.

The only way to fix it properly is to pull the radiator, drop the pan, pull the head, remove the timing cover, and start over with the seal installation. A total aggravation, but we have all been there. Why you have black oil coming out of the leaking seal is very mysterious, I am at a loss as to why that is happening.

Tom Brady

From the photo, we can see that you used the XJ6 Teflon seal and the associated tapered distance piece. What is the silver strip that appears to wrap over the top of the seal?

That’s my drawing. I can guarantee you that it was drawn to scale with all of the parts laying in front of me.


Yes, Tom, we had quite a discussion on this topic fairly recently. I’m planning to leave the head in place and remove just the timing cover and sump. The timing cover can be removed with the head in situ, I believe, but is a bit fiddly, requiring studs to be removed with double nuts. Water pump needs to come off, too.

If I took the head off I don’t know how I could possibly support the front of the engine (I have the early sandwich engine mounts on the plate). You can’t support it under the sump, as that needs to come off!


Hi Chris,

The original poster said that he will use “the engine lifting bracket so it can be supported overhead”. Perhaps he is speaking of the engine lift brackets that attach to the cylinder head nuts? That would be a easy solution. All of this is very interesting to me because of the 1950 early engine in my Mark IV.

not sure it’s a good idea to disturb the torque setting of the two front head studs to put longer ones in (temporarily) to take the lifting bracket…