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BJ8 rear main seal kit - is it necessary and worth the risk to install?

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steveg said:
My understanding is the Healey has a reverse archimedian screw in a bore. Like a meat grinder in reverse. The "threads" move in a reverse direction, in theory always pushing any oil overflow back toward the crankcase.
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Totally correct and reminds me of my Lithuanian grammy making kielbasa with a side of fresh ground horseradish. It was all about the Archimedes screw meat grinder.
 
steveg said:
Keoke, the Healey doesn't have a labyrinth seal. In the linked wikipedia article male discs on the shaft rotate inside matching female areas - any excess oil is slung off by the first disc or two. As far as I know there's nothing like this on the Healey engine.

My understanding is the Healey has a reverse archimedian screw in a bore. Like a meat grinder in reverse. The "threads" move in a reverse direction, in theory always pushing any oil overflow back toward the crankcase.

Perhaps Randy in his vast collection has a picture of this part of the crankshaft.
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Really???

The labyrinth seal has a number of grooves which interlock with other grooves or teeth. This differs from most traditional seals, which use a single lip in an attempt to seal an opening. With the labyrinth seal, each groove acts as its own lip, distributing pressure across the seal rather than concentrating it in one area. While a labyrinth seal cannot deal with high pressure differentials, it can be used in many other types of environments.

I thought it qualified?
 
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Keoke said:
Really???

The labyrinth seal has a number of grooves which interlock with other grooves or teeth. This differs from most traditional seals, which use a single lip in an attempt to seal an opening. With the labyrinth seal, each groove acts as its own lip, distributing pressure across the seal rather than concentrating it in one area. While a labyrinth seal cannot deal with high pressure differentials, it can be used in many other types of environments.

I thought it qualified?
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Hopefully someone will respond with a photo of that area so we can see what the configuration really looks like. One might argue the Healey setup is a poor-man's labyrinth seal because it has no matching male and female components.
 
steveg said:
Hopefully someone will respond with a photo of that area so we can see what the configuration really looks like. One might argue the Healey setup is a poor-man's labyrinth seal because it has no matching male and female components.
Click to expand...

Correct..... it is a form of Labyrinth seal . grooves cut into the crankshaft act as the pressure equalization points .(not sure if that's the right description)
I deal with this type of seal all the time on the centrifugal chillers I work on but in reverse . The seals I deal with have a stationary grooved portion which is in position around the nose of the rotating turbine wheel .
 
DONE--Re: BJ8 rear main seal kit - is it necessary and worth the risk to install?

Seal installed with no installation issues. Thanks to all who said "while you are in there" to go ahead and install the seal. Go the seal from British Car Specialists. I believe the seal is the Denis Welch unit as it has the square housing. Hopefully we will see how it works in a couple of months. Thanks again to all.

jjs64bj8
 

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Good job, you will be glad you did it ! The scroll seal design wasn't too bad for 1955 technology. If all clearances are perfect it didn't work too bad but did drip. With any wear at all on any of the surfaces and you have a real leaker ! Good luck
 
I've had 3 big Healeys (two BN4's and a BJ8) spanning about 44 years and have never
had a problem with the original scroll design so I've never bothered with the rear
seal kit. But I've never had to park on steep hills and believe a few oil drips are just
a way Britmobiles mark their territory. Would only consider putting in a modern
rear seal if oil was getting on the clutch. My $.02
Steve
 
As I initially posted, I was reluctant to install the seal, but since the car is just now going back together and motor is still out I decided why not after many supporting replies. When the time come to finally sell the car (when we get too old to enjoy the restoration), having the seal might be a good selling point, especially if the car ends up in a hilly environment. But for now we here in Florida do not have many steep hills!

Thanks

jjs64bj8
 
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