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Engine rope rear main seal in early Mk1  Rate Topic 
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 Posted: 12-09-2017 02:28 pm
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scottsmi
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Hi All,
I know I have read many posts about the famous rope seal leaking. I have 500 miles on my rebuild and now have a pretty good leak at the rear of the engine. I took the bell housing cover off and sure enough there it is. So now gathering info on what to do next. Talked to Delta and he said that this leak was so common that lotus changed the block the next year for lip seal. He said if I fix it there is an 20% - 25% chance that it will leak again. I am pretty good at building engines so I am not worried about pulling it out as such but don't have the "old knowledge about installing the rope seal" or if there is a better way. The only problem with using a different block is that I have done extensive machine work to this and not sure if I could transfer pistons, crank, etc without more machine work. So any ideas?

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 Posted: 12-10-2017 06:26 am
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Esprit2
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The rope seal is flawed by type. It's old school, and less than perfect. If you install it perfectly, it may still leak. If you get it a little wrong, it will leak. I can't think of a scenario in which it's reasonable to expect that it won't leak. If not right away, then at least in far less time than would be acceptable after a rebuild.

The critical fit for pistons is with the liners, not with the block.

The downside to installing a Mk II block and main bearing panel would be the loss of the engine serial number. "IF" you have a collector quality example of a JH, then matching numbers mean something. They're significant. If you're car is something other than collectible, then the upgrade to a rear main lip seal would be more of a positive than the loss of the engine number would be a negative.

If you replace the block, then you must also replace the main bearing panel. They were match-machined during manufacture, and are numbered as pairs. If you just get a block, then it and the old MBP must (!) go to the machine shop to be align bored as a properly torqued assembly.

Regards,
Tim Engel

Last edited on 12-10-2017 06:28 am by Esprit2

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 Posted: 12-10-2017 01:09 pm
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scottsmi
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Thanks Tim, You have stated my struggle perfectly in that I have fully restored an early numbers matching JH. I recently won a ribbon for 1st place as peoples choice in my class. I think I can live with a little leak because that is the character of the car. This leak however is a steady stream. So alas, I must do something.

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 Posted: 12-10-2017 09:11 pm
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Esprit2
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Just a general statement about rope seals... I don't know how specifically this applies to the Mk I 907's seal.

In the 1980s, asbestos and some other key materials in many old rope seals were declared hazardous and removed from rope seals. The result was neutered rope seals that were no good from the day they were made.

Technology has since caught up, and modern asbestos-free rope seals are once again much better.

When you buy a rope seal, either look for really old NOS parts from the '70s, or very current, new parts. But do not buy NOS (New Old Stock) rope seals manufactured during the 1980s & 90s. For the most part, they were crap to begin with and didn't get any better with age.

Regards,
Tim Engel

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 Posted: 12-11-2017 11:44 am
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chrisl
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I have an early J-H and had to replace the rope seal not long ago. Same issues as you re originality...

The first one I got from the club store unfortunately didn't fit; wrong type entirely.

I bought two (the first shop who had the car went bust and lost a few of my parts, including the seal, a long story) from Ross Hockley in Sydney. His email is jensenbits@gmail.com or you could try ringing on +61 2 9938 1822 but the time difference might be a challenge. Ross is very knowledgeable about J-Hs.

Anyway, it fits perfectly and no oil leaks (from that part of the motor anyway!).

The rope seal is not uncommon for cars of this era; you will also find elsewhere on this forum some great tips to ensure it's properly seated and does as good a job as it can.

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 Posted: 12-11-2017 11:49 am
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chrisl
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And here's the link to an earlier post that might help:

http://www.jensenhealey.com/forums/view_topic.php?id=1763&forum_id=2

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 Posted: 12-12-2017 12:43 am
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scottsmi
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Thanks for the info on the Australian source. I think I am going to reach out to Ross in Sydney to see what he thinks, should be interesting to learn. Also it was interesting in the link about it being a ford seal. Seems like I could measure the seal and search for it that way. Turns out Jags, Rover’s V8, Allard (Cadillac 331), etc. have a rope seal as well. I know they raced these early cars and should have been able to install rope seals that could handle high oil pressure. It might be worth while to check a Jag forum. I installed them on my 57 chevy 283 that I had in high school.

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 Posted: 12-12-2017 01:12 am
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chrisl
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Indeed the mechanic who sorted mine works a lot on early Jaguars; he said it was run of the mill stuff for them.

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