Building 74 V-12 - Residual rear bearing cap and seal questions

I am finally ready to start reassembly on the V-12 from my 1974 E Type. I have tried to read all of the advice about gaskets, sealants and the rear main seal. What is clear is that people have used different materials and approaches. I want to make it as leak-proofed as possible consistent with not doing anything to mess up clearances. I think I have boiled my questions down to the following:

  1. Is it true that I should put nothing between the rear main bearing cap and the block? If not, what is used?

  2. Is there any concensus on elimination of the side hockey stick seals in favor of the black RTV injected after torqueing down the cap); putting some sealant on the hockey stick; or another option??? I saw a suggestion elsewhere (on a different engine) about putting a 1/4 inch shot of black Loctite into the side seal channel and then tapping down the side seal to force the sealant into all the gaps, but I don’t know if that is applicable to this engine.

  3. Is there any merit in soaking the rope seal in oil or using some sealant in the channel before installation of the rope seal?

I know this subject has been close to worn out, but to my muddled brain the clarity level of the conclusions in the discussion is only a little better than the oil I drained out of my engine. I hope some of the veterans with non-leaking engines will indulge me on these questions.



To clarify my request for clarification, in question 1 I meant the bottom of the bearing cap.

  1. If you do not put anything between the cap and block, it will leak.
  2. I do not use the “hockey sticks” as they are plastic and will eventually shrink and leak. I put Avaition Form a Gasket on the top face of the rear cap and torque it down. I then take a fresh tube of Ultra Blue or Black and inject it into the groove where the hockey sticks went until it comes out the side channels along the top corners of the cap.
  3. I install the seal dry, size it using the proper factory tool and then apply oil numerous times to soak in.
    This has always worked and engines stay dry at the rear.

Thank you, Dick. That is a very clear outline of procedures, and I appreciate it.

And for anyone else reading this in the future, by “bottom of the bearing cap” in my earlier message, I meant bottom with the block flipped upside down, which of course is really the top. :slightly_smiling_face: Thanks again.

I tried installing the rear seal dry tonight per Dick’s process. Best efforts to roll it in with a piece of pipe did not get it in as far as expected, so I put in the sizing tool and bolted down the bearing cap to force the issue. After doing so it took all my strength to rotate the tool after starting it with a rubber mallet, although it loosened up a little after the first few partial rotations. The seal I used was a gray graphite-looking one rather than the white one that came with a gasket set. Tomorrow I will take off the cap, oil the seal some more and try again.

Does this sound at all normal or should I pull out that seal and start over?



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After a second session with the sizing tool on the new rear seal and oiling the seal the rotation loosened up enough to get me to proceed with the crank installation. With everything lubed and torqued to spec the crank turns easily with a wrench on the end pulley bolt, but it does not turn easily by hand. So it is a bit more effort than I expected.

The crank just needed a polish and since all journals were in spec it was reinstalled with new standard size bearings. All caps are back in original positions.

I think the rotation resistance is a combination of sticky assembly lube and the new rear seal. Before I tear it back down and take a second shot with another rear seal, I am hoping the veterans can give me a gauge in terms of the expected level of rotation resistance with a newly reinstalled crank with a new rear seal.



The gray graphite seals are the good ones. The white ones are junk. They tend to rear apart / shread when sizing. Cranks are tight with the new seals. Good thing you did not machine the crank. The V12’s do not have undersize bearings available on the mains. Sounds like an aftermarket gasket kit. Make sure you have the cometic style cam cover seals, not the paper ones.

Dick, I redid it with a second gray graphite seal which was a bit more flexible and seated better than the first one. I did not use the white one. I now have the short block done with all pistons in and the crank turns with a reasonable level of effort.

I got Cometic head gaskets separately + the SNGB gasket sets. I am not sure what the Cometic gaskets look like for the cam covers or where to get them. The usual U.S. vendors seem to offer the gasket kits with a mix of different gasket types. I was looking to do everything in Cometic gaskets but was not aware any Cometic sets were available for the V-12.



The genuine Jaguar gaskets for the later XJS are the Cometic style ie: stamped aluminum with rubber bonded on either side. They will fit the E-V12

Excellent - Thank you.


One last question, Dick (for now). I have seen that Cometic gaskets are put on dry. Would that also hold true for the Cometic style cam cover gaskets? I have probably seen at least 20 different techniques described for sealing the cam covers and it gets confusing. I have the aluminum half-moons to use in place of the rubber pieces, and I know some sealant at least needs to go around those.

You don’t put sealant on rubber. However, you can put a dab of silicone sealer where a gasket meets up with a rubber seal or o-ring. Do put a smear of silicone around the aluminum piece where it goes on aluminum. No need to put it on the face where the cometic gasket goes.

Great, thanks again.