3.8 Series 1 - specific : Removing The Sump And Changing the Sump-To-Seal-Carrier Seal ?

[rfs1957]

Can someone with a 3.8 (different sump ?) that has actually DONE this, and recently, so they remember everything (I couldn't), tell me what's necessary when one wants to get the sump off, please ?

I have read just about everything I can find on the Forum about this, but didn't find anything about doing it specifically for the rear sump seal.

First, the context.

I have been squirming with embarrassment since I totally rebuilt my car (2018-2024), as having made something of a personal crusade around the snake-oil rear-crank-seal merchants, and supposing that I had got to the bottom of it ...........

viewtopic.php?f=3&t=16408&p=134682&hili ... al#p134682

.......... I then discovered that I had a - er - leak from the back of the engine

If you didn't see that post, this picture should whet your appetite for the "thesis" :



HOWEVER, the problem I now have is, I think, from the seal between the sump and the rear seal carrier.

Here's why.





First of all, in order to be able to use the car I fitted a "period accessory" from the mid sixties that enables one to hide a couple of sponges from any casual glances in the locker-room, and found that I had an autonomy of about 1.000 kms before any drip became visible.





This was to give me time to lick my wounds and pretend everything was okay.

After eliminating everything else - cam-feeds leaking, main oil-gallery plug loose, weeps from the tacho-drive, cam-cover weeps drifting backwards and then south, it became apparent that the leak was not so much mileage-dependant as time-dependant.

Incidentally, and someone did mention having had a problem here in another post, that gallery plug can leak, and here's the tool that makes it possible to tighten without removing the engine.



The flywheel is oil-free to the point of even having traces of rust, which - legend has it - precludes it being the actual crank seal, although I was suspicious that if the pressed-steel cover was a really close fit to the crank - as I believe mine is - then it might just cream off any leaks and divert them away from being centrifuged by the flywheel.





Scrupulous cleaning of the whole area with brake-cleaner showed that after 24h with no engine use there was already an incipient drip :



right at bottom of the visible sump-to-carrier seal, which very definitely originated there rather than being from the crank-seal per se, as a cotton-wool bud wiper on that specific small zone drew a blank.

48h had the weep accumulating under the back of the sump :



and then 72h saw the first drip on the floor.



Pictures below are from during the 2020 engine assembly.





Now I assembled this engine in absolutely perfect, accessible, clinically lit conditions ; and the sump-to-seal-carrier procedure is hardly a complicated operation.



However, I can see from the above picture, taken during the rebuild, that I used a "modern" rubber-cork rear seal, as this is what was supplied by SNGB ; this was before I moved to sourcing everything from Rob Beere, from whom I will now no longer deviate.

(Update - see further on, in fact that picture was from the Phase One build, which I later ripped apart again, before finishing the engine, and I did in fact complete Phase Two with the more modern "correct" Jaguar black rubber/plastic seal, and with Cometic side-gaskets rather than standard gaskets with grey RTV.)

I'm nervous about having another go at this, with the engine in-situ, as if I cocked it up "in the lab" then what chance have I got with it up on the car-lift, with my arms in the air ?

I think my main questions are ;

1. are those rubber-cork rear seals known to be crap ? Even when fitted with a gasket compound ?

2. with the crank in the right position (which is ?) will the sump come off without having to remove the reaction plate (which means the exhausts) ?

3. is that easier than trying to lift the engine to get more room ?

4. does the crank damper assembly have to come off - I otherwise wasn't going to touch the front oil seal, which is fine.

No postcards please, just concise electronic answers, and with a bit of luck Australia will chime in overnight, always a pleasure to read over breakfast.

[44DHR]

Rory,
Concise answers :-
1. Yes.
2. No on a 4.2, so pretty sure No on a 3.8.
3. Yes.
4. No.

See my post regarding replacing duff shrunken cork seal with ribbed rubber rear seal :-

viewtopic.php?f=3&t=19921&p=161846#p161846

Crank position has to be set correctly, but reaction plate still has to be removed to drop sump down if front pulley left in place - which I did not remove. Post above details fitting temporary dowels into rear of torsion bar mounting to keep the bars in place so reaction plate can removed to drop sump. The difference in the rear of the 3.8 sumps and 4.2 sumps is covered in another of my posts below, but this difference explains why I believe answer 2 should still also be “No”. Hopefully, the photos still work, but basically the photos show the 3.8 sump has a single curved sealing area to place the seal onto, whereas the 4.2 sump has an extended area with a curved groove to place the seal into.

viewtopic.php?f=3&t=4256&p=28996#p28996

Hope this helps,
Cheers,
Dave

[nichmoss]

I have removed the sump from my 3.8 without removing the reaction plate. It was a long time ago and I don't remember the crank setting to do this but someone will - I think you're trying to level the crank (best as possible) for cylinders one and two (rear of the engine).

I am pretty sure that I left the damper on but loosened/removed the vertical steady bar so that I could lift the gearbox slightly. The car was on ramps and the access is fair but you are lying on your back so it's uncomfortable.

Good luck and I'm sure someone will drop in with the crank position.

Chris

[mgcjag]

Hi Rory..Worth a read here and explains crank position..Steve https://forums.jag-lovers.com/t/e-type- ... val/450751

[david muir]

I, too, have removed the sump on my 3.8. Again, it was a while ago but I didn't have to remove the reaction plate or the front damper. I also don't remember having to have the crank in a certain position but easy enough to turn with plugs out.

[44DHR]

I think we’re getting towards an answer Rory, but either way - removing the Reaction Plate, or alternatively the Front Pulley, or jacking up the block, or removing top engine stabiliser - you have choices.
My preference would still be to remove the Reaction Plate as this gives a clear run when reinstalling the sump and takes away the worry of the new rear seal getting out of position on installation if you choose to jigger it over the Reaction Plate.
As regards the exhaust, as I have headers, I just unbolted them from the head and left the exhaust system attached so they just dropped down to give me room to unbolt and subsequently re-bolt the sump as there are a lot of bolts to work on while the sealant remains in a workable state. I did manage all this with the car jacked up on stands and laying on my back, but with my wife assisting with the trolley jack to hold the sump up guided by temporary dowels in the block.
Cheers,
Dave

[tim wood]

Mine is a 4.2 and I have no experience of 3.8 but…
When I first dropped the sump with the reaction plate in place I used a cork gasket. Result was a good leak.
On removing the sump it was clear that the cork had become slightly dislodged during sump fitting.
I refitted with a rubber gasket and all well.

The issue I believe is that if you leave the reaction plate in situ then the sump must be canted to get it in place whereas with the removed it’s much of a straightforward positioning.

Tim

[rfs1957]

Many thanks indeed for the input so far.

Long chat with Rob Beere and Carl this morning, they use the genuine Jaguar ribbed rubber seal C36499 and NOT the SNGB C36499* which is a copy.

TBH I wont’t know what I actually used until I get the sump off as I know that I “went back in” after worrying about the vile split-seal method that I had initially adopted.

I used to be confused and now I am not so sure.

I will however definitely get the reaction plate out as a straight/level approach upon reassembly appears to be a must.

PS - look at the picture above that shows the sump baffle plate, Carl pointed out that you can see in its past life where a bent dipstick has failed to hit the bulls-eye and put scratches everywhere, as well as provoking significant overfilling. I only got 8.20 litres out this morning, so at least I didn’t get that wrong as well.

[Simonpfhc]

I’ve got the exact same problem as you Rory, so all this info is going to be useful to me too

[rfs1957]

Suspension dismantled, torsion bars relaxed, exhaust system on the floor, reaction plate off, and sump drops off a dream.



I think irrespective of crank position, tho I was perhaps lucky with cylinders 1 and 2 being mid-stroke.



Even with the Aussie damper, which I think sits a little further back, the critical pair of nuts at the front nose remain accessible and there is no need to remove the front crank components.

And the front seal looks quite undisturbed, ready to be re-entombed.

I had in fact used the black grooved rubber “official” seal, at the back, NOT the cork/composite one, just shows how even ones pictures can be misleading - I had indeed gone back in for a second go, but was too ashamed to take any pictures.

It looked like I had just been too parsimonious with the gasket sealing compound on either side of the rubber U-seal, trying not to behave like every other fast-and-loose mechanic - they obviously know better than I do, me with my pussyfooting neatness.



Ready for Round Two.

[rfs1957]

Interesting to note where the oil-level is, in practice, as I've heard (and probably ;-(( made) wild claims about its effect on leaks.

I've not seen this properly measured elsewhere ? Give or take 5mm I would think.



I reckon from these measurements that with the dip-stick reading max, on my engine this puts the oil level such that the wire-basket's collar is fully submerged, but the baffle plate's front and rear upper slopes are dry.



Hence the rear sump seal is about 5cms higher than any normal oil level, and the front crank seal some 9cm above that level.



It would therefore take fully 7.50L more oil beyond the usual 8.50L max (22cm x 68cm x 5cm ?) to get the rear seal permanently wet, to feed any leak.

Drips, then, from the rear seal - when static - are coming from the oil that's inside the crank, or above it it, on the block walls, that is draining back past the rear crank main.

[mgcjag]

Very good oil level info and drawings here....Steve viewtopic.php?f=3&t=19928&p=161932&hili ... ng#p161932

[rfs1957]

Doh - so Dave Rose got there first ; teach me to engage Search before Keyboard.

Here is his original posting, referred to in the one you have highlighted Steve.

viewtopic.php?f=3&t=19922&hilit=%E2%80% ... pacity+%3F

[rfs1957]

Waiting for new parts, I have been trying to work out why this leaked in the first place.

I had used a reasonable bead of Loctite/Henkel 5910 gasket cement both on the seal-carrier and the sump, buried the ends of the Cometic side-gaskets correctly, and the seal was a genuine Jaguar one from Rob Beere - and it was correctly centred.

But it didn't look like it had found it hard to let go when the sump came off.



Now the diameter of the sump orifice measures up at 132.50mm, and the diameter of the seal-carriers (both new-type, for the Flexi-seal, and the old-type, in my case for the scroll) is 122.50mm on both.



That suggests the gap we're trying to fill is about 5.00mm.

Yet the old seal measures about 5.30mm on the shoulders, which already seems a bit thin for the application, and in the centre it measures up at only 4.30mm.



It's been in place for about 5 years and maybe 4.000 miles.

You would have expected a flexi material in that context to be 6mm at least, and have a genuine crush on it, with some residual spring in the material, no ?

And for the seal to look like it had been entombed in sealant ?



Which it doesn't.

What am I not grasping ?

[Gfhug]

Is it just incompetence in the original design of the seals, Jaguar or not, and an acceptance of weeping seals as normal? Might sound silly but I could believe it from that period of industrial strife

Geoff

[Series1 Stu]

Hi Geoff

It is ludicrous to suggest that the engineers working at Jaguar were incompetent or negligent in any aspect of designing and engineering these magnificent cars.

Given the number of times we heard Norman Dewis regale us with stories of constant intensive testing of these cars under all sorts of adverse conditions do you seriously believe they would let something like an oil leak pass into production vehicles?

It's amazing how dismissive lay-people can be of the hard work and diligence of the people that worked so hard to bring us the machines that still delight us 60 odd years on.

It's more likely that the sizing issues are down to the parts suppliers giving us whatever falls easiest to hand.

Regards

[rfs1957]

Yes, no suggestion that the design is bad ; it just requires a seal that is of an adequate section, and the use of an appropriate sealing compound.

I’ll speak to Beere’s on Monday.

Would anyone have a new one of either of the seal types to hand, the all-rubber or the cork/rubber, and could measure the thickness ?

[Gfhug]

Hi Stuart

I was not trying to be dismissive of all the hard effort put in by Norman Dewis et al. But more thinking along the lines of your last sentence and I apologise for the poor way I expressed my thoughts. How much is down to the poor seals supplied to Jaguar and marketed under their name?
Manufacturing precision has improved remarkably since the original design of the XK engine.
My engine, and others report similarly on here, has a steady weep, something I’ve accepted as inherent in an engine design from the 1940’s.

Stuart, please accept my apologies.

All the best

Geoff

[40GT]

The thickness of your seal at the lowest point ( 4.30mm ) is dictated by the sump gasket. Unless of course there's something wrong with the sump ( skimmed perhaps? ).
I would be looking at the centre line of the crank and taking some measurements from there to compare vertical to horizontal.

Sean.

[mgcjag]

Hi Rory...Worth a read here and Dick Maury,s reply....Steve https://forums.jag-lovers.com/t/rear-su ... ion/443364