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Dennis Welch Rear Crank seal conversion - Gap in back plate

RestoreThemAll

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Hey guys,

I installed a rear crank seal conversion this past weekend. I like the seal. It went together fine with no struggles or issues.

I used the template supplied with the kit to cut out the back engine plate giving space to clear the new seal frame. If I put the template up to the back plate it looks like a perfect modification. I'd have to double check but I think the finished product came to 7 5/16". I don't have it in front of me.


There is a small gap of maybe an 1/8th inch or so between the rear main cap and the plate where it meets the back of the oil pan. The plate before it was modified come down over the block and sealed with the gasket. My concern is that road dirt, rain, etc... will enter that gap and cause damage to the crank seal or clutch. What should I do with that gap? Has anyone who has installed the seal experienced the potential problem?

Thanks for your input.
Dale
 
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RestoreThemAll

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attachment.php
attachment.php
Here are pics of the rear seal installed.
 

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  • Rear seal installed engine side.jpg
    Rear seal installed engine side.jpg
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  • Rear seal installed gear box side.jpg
    Rear seal installed gear box side.jpg
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RestoreThemAll

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attachment.php
this pic shows the seal without the rear engine plate
 

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    Rear seal installed no plate.jpg
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There is a small gap of maybe an 1/8th inch or so between the rear main cap and the plate where it meets the back of the oil pan. The plate before it was modified come down over the block and sealed with the gasket. My concern is that road dirt, rain, etc... will enter that gap and cause damage to the crank seal or clutch. What should I do with that gap? Has anyone who has installed the seal experienced the potential problem?

Thanks for your input.
Dale


There is a cork gasket that fits in there. It's in the 'Gasket Set, Sump;' Moss part# 525-003. It's also in the 'Conversion Gasket Set;' Moss part# 522-025. If you don't fit it, I suspect you'll get a prodigious leak at the rear of the pan. If nothing else, fill it with a sealant.
 
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RestoreThemAll

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Bob,
The oil pan gasket and felt plugs should take care of sealing the oil pan. Well, we'll see about the felt plugs. :playful:

I have a gasket set from AH Spares. I'll dig through that tonight and dry fit all that I find.
Thanks for the assist.

Dale
 

steveg

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An old timer, Ken Rocke, suggests cutting the tampons (felt plugs) into 1/4" lengths, coating them with silicone sealant and driving them into the holes with a drift.
I coated both sides of the gaskets and the square piece mentioned above in Hylomar.
The picture shows the areas painted with Permatex Aviation Form-a-Gasket. This included the halves of the seal carrier and where it mated to the block and the vertical joints in the rear bearing cap and the area around the cam bore. In addition, I sprayed the mating area on the engine plate with several coats of Permatex spray copper gasket.

https://www.pbase.com/stevegerow/image/97270433

With the engine out, it is easy to do a super job on all this sealing.

It leaks a drop every now and then, but has been basically leak-free for 7 years.
 
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RestoreThemAll

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Your timing is perfect for my project Steve. Thanks!

Bob, I did find the square shaped gasket in my AH Spares kit that you pointed out. It sits on top (bottom really) of the main cap and is captured by the plate. I was assuming incorrectly that the plate gasket was all there was, and that had to get cut with the install of rear seal kit.

If I ever cut a plate for a rear seal again I will NOT completely go by the cutout template. Using that template I took off too much material! The plate doesn't catch the gasket that sits on the edge of the main bearing cap as well as I'd like it to. Using the Form-a Gasket it should be fine.

I should add that I'm not being critical of the cutout template or those who created it. I'm guessing that the plates on the old cars weren't cut exactly, perfectly identical.

Thanks for the help guys. On to the front plate and timing gears/chain.
 
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Gary H

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I knew this sounded too easy! I am installing the Dennis Welch rear main seal with the engine still in the BJ8. Rear of the block has been drilled and tapped. How do you get the rubber seal and spring installed on the crankshaft? Do you try to connect the spring ends after the rubber seal is on the crank and roll it into the seal? Not much room between the block and the rear of the crank. The spring doesn't look like it would stretch around the end of the crankshaft if installed in the seal. I have searched the forum for this hope I didn't overlook the answer.

As a side note I thought the rear seal was the leak. (new engine oil and new gear box oil look the same) Turns out to be gear oil coming from one of the bottom bolts from the clutch housing to the gear box. Since I have gone this far might as well add the rear main seal.

Thanks for any help before i need to order a new seal.
 

steveg

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I knew this sounded too easy! I am installing the Dennis Welch rear main seal with the engine still in the BJ8. Rear of the block has been drilled and tapped. How do you get the rubber seal and spring installed on the crankshaft? Do you try to connect the spring ends after the rubber seal is on the crank and roll it into the seal? Not much room between the block and the rear of the crank. The spring doesn't look like it would stretch around the end of the crankshaft if installed in the seal. I have searched the forum for this hope I didn't overlook the answer.

As a side note I thought the rear seal was the leak. (new engine oil and new gear box oil look the same) Turns out to be gear oil coming from one of the bottom bolts from the clutch housing to the gear box. Since I have gone this far might as well add the rear main seal.

Thanks for any help before i need to order a new seal.

I installed the seal like this Jan 2008 - it still doesn't leak:
rearSeal.jpg

After inserting the pins, I cut them off flush and installed the seal with the spring toward the engine.
 

Keoke

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I do not know for sure, but you could probably seal it with an engine type RTV gasket sealer-Just a thought?
 

Gary H

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Now I see, the pins hold just each end of the spring allowing it to spread around the crank! Thanks for the help. I was having to remind myself why I enjoy working on this car.
 

steveg

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Now I see, the pins hold just each end of the spring allowing it to spread around the crank! Thanks for the help. I was having to remind myself why I enjoy working on this car.

My reasoning was that using the pins, the spring tension is insignificantly less than if the ends were hooked together, but installation is much easier and can be done with the spring side toward the engine which is the correct orientation.
 

Bob Hughes

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When I installed my rear seal with the engine insitue, I connected the spring together over the end of the crank shaft and then slipped the rubber seal on and then came the tricky bit to install the spring into the seal. Working from underneath and after many aborted attempts I came up with the idea of using a piece of old metal coat hanger, flatten one end and turn it through 90 degrees so it projects out about 5mm and with a slight curve to hook over the spring, the other end was formed into a triangular shaped handle for control. I then slipped the hook over the spring and introduced it into the seal and gently turned the seal by hand feeding the spring in, all in all it took less than a minute. Best of luck

:cheers:

Bob
 

Gary H

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Finished the rear main seal today. Pins to hold the spring worked well. Aircraft Form-A-Gasket added a little extra insurance. Taking the rear plate to the machine shop next week for the cut out. It's nice to get one phase of this project checked off! Thanks for the help.

Gary H
 

Stretch

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I wasn't able to get oil to stop leaking around the new seal mounting hardware. I, too, took too much material from the backplate by following the cutting template. It took about one season for oil to work its way through the cork and sealants I used to seal the gap. On a second attempt I inserted a .004 SS metal shim plate hoping to reinforce the sealant. It didn't work. The seal around the shaft is great though. Good luck to you. I gave up and leave what I affectionately call a diaper under the car.
 

steveg

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The block also leaks at the vertical joints where the rear main bearing cap slides into the block.

The felt plugs are supposed to fix that but get soaked with oil. An old timer told me he had cut the plugs into 1/4" sections, coated them with silicone sealant and seated them in their bores with a punch. It would be great if there were a type of silicone with a skinny nozzle and the ability to fill the bores from the top down without any bubbles.

Maybe some gutsy person could drill a breather hole in the top of each joint so one could inject silicone from a tube until it bled out the breather hole.
 

busybrit

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It's not easy. I just did one this week with the engine out of the car. Next time I rebuild a Healey engine I'm going to fit the spring to the crank. BEFORE the crank gets fitted to the block.
I would practice connecting the spring on the work bench a few times. Then take it to the engine with long nose quality pliers it can be done. Another thing I do is to use electrical heat shrink to cover the spring joint, just a small piece. This prevents the joint from coming undone when you are rolling it into the oil seal.

Johnb
 
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