Starting main rear seal and crankshaft reassembly. Words of wisdom?

Hello all,

the time has come to reassembly the XJ6 SII engine.
New stock size top hat cylinder bores, new +10 crankshaft bearings, crankshaft it self needed only a good polishing.
I am now here:

I have read lots of threads, watched many videos, including this one:

I have:

  • Oil soaked rope seals
  • Assembly lube
  • GM sealant
  • Oil resistant RTV
  • Spare crankshaft (good condition) to use as main rear seal sizing tool
  • Lint free cloth
  • Razor blades
  • Torque wrench

My objective for next Saturday is to fit the main rear seal and crankshaft in under 3 hours.

I’d love last words of wisdom before I get into what seems to be a procedure reminding me of the operating theater and orthopedic surgery…

Thank you :slight_smile:

Yeah um, erm… try to enjoy it, big fat hammer and something to save the crankshaft; and best of luck! Keep the videos coming if you want - did I say how much I like the silver engine bay…


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Rear main seals of the “rope” type can be problematic based on my many decades with the warranty department of Jaguar USA. We had to continually remind dealer service departments that the crankshaft rear seal sizing tool must be used to ensure correct clearance between the seal and the wearing surface of the crank. Too little clearance and the seals overheated and leaked, too loose and they also leaked. Toward the end of XJ6 III production we had instances of bent cranks that caused the rear main bearing to wear excessively and also interfered with the seal function as well. The only acceptable fix was to remove the crank, have it straightened and replace the bearings and seal using the factory sizing tool. . Even when done properly rear main seal leaks can occur hence the availability now of updated seal kits. However, I have no experience in how well they work.

I am a little confused by your comment “new 10+ crankshaft bearings but the crank only needed a good polishing”.

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Thanks for this.

On disassembly we found that the crankshaft had already been reground to +0.10 and was in great condition, so only replaced the +0.10 bearings with new suitable ones as a matter of course.

Guess I just lucked out, for all those years…:grimacing:

A note…the oil filter canister is the exact circumference as the proper Churchill rear seal sizing tool. I WAS ABLE TO USE IT. IT WORKED. at least for the last 2 years I have no leaks.
Having said this, obviously, I would use the Churchill…if I had it…
And, that is an excellent video…thank you for bringing it to my attention
Might ask…can I get the exact title of the video…youtube has become difficult to deal with
Also, the oil canister as fitted to the 4.2 E type…oil filter canister with a cartridge filter

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Only ever used the sizing tool as an apprentice. We used a ball pein hammer and trial and error - helped with “ Rocol” and a light smear of silicone sealant on the back of the seal, to prevent the ropes turning. Too tight causes burning. Plenty of lubricant on start up is the key. Having said all this, every crank we fitted, was reground and checked for straightness. Make sure you check the crank end float.

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You mean this video?
“Holden V8 Rear Main Seal Installation”

Yes Eric,
Thank you…and I have your videos marked

More or less the method I successfully used on all rope-sealed engines I rebuilt, from Jaguars, Austins, Triumphs, and Fords. I never had a “factory tool”, and none leaked beyond the amount any rope-sealed engine leaked from there.


I am sure I read that you can use the crank to use as the sizing tool ,
Put it all together , then tighten the top down a little at a time , turning the crank a lot before you tighten down a little again !

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No, you cant do it that way.

You install the top rope the same way shown in the Holden video, and then use the crank, tapped down with a dead blow hammer, then trim the rope.

The bottom (cap) is then treated the same, tapped down onto the crank, trimmed, then you can torque down the cap.

It also needs to greased, to aid in proper break-in.

Of course you can , more then one way to skin a cat , but I would not be cutting it :laughing:

Well, I can assure you, if as much protrudes beyond the ends, as in the Holden video, you will NEVER “stuff it in the groove.”

Some ropes were the correct length, but most I saw were too long. I cut them, as needed, and never had an issue.

Our seal protruded a lot and it was very much as far in as you could ever get it. The seals we got were too long which is a shame really because when you do it the first time it is annoying enough to get the thing in the groove at all!

Ever seal that I have replaced (both 6 & 12 cylinders) were always why too long. Always needed to be trimmed. In all cases, I was lucky enough to borrow (locally) the correct sizing tool. JS

What is the sizing tool, what does it do? Does it cut the seal or do you refer to the churchill tube?

I guess you mean the churchill… the crankshaft is about as good and for cutting the Tool is out, or do you have a different way?

I rebuilt my 1967 3.4L engine last year.
The Churchill tool I borrowed from JCNA had a sizing diameter of 3.119". The crankshaft seal diameter was 3.125". So assuming no seal springback (unlikely) the crankshaft will compress the seal by at least 0.003" radially.

I did not trim the seal and the gasket set I used came from SNG Barratt as Payen EE532.

It was pretty hard to turn the crank after the seal was buttoned up. With the seal oiled, it took 25 lb.ft. to unstick the rotation, obviously less once it was turning.
The car has done 2000+ miles since the rebuild and there have been no obvious signs of oil leakage or other distress.
If you live in the US, I do recommend borrowing the Churchill tool from JCNA as all you pay is shipment in both directions as well as a security deposit.

This all may not be the cheapest way to go, but OTOH do you want to repeat the exercise if there’s a problem? I think doing it the way the maker intended is probably a good way.

I think Coventry Foundation also lends special tools but this may be the same organization as JCNA now. Here is a link.

The tool does the exact same thing as the crankshaft; Maybe even better if it had been ground before!