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Rear Crank Seal Kit

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Michael Oritt

Michael Oritt

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I'm having my 100's engine done this winter and though it's not a terrible leaker I''d like to install a rear seal kit to tighten things up as much as possible.
I know there are several different kits available and would appreciate any input on which one to select along with installation tips.

Best--Michael Oritt
 
Michael, Which kits are you considering? I've installed one and seen at least one other advertised, but they didn't seem to have much, if any, differences.

Note any kit AFAIK for the 100s requires machining the crank and some re-shaping of the rear engine plate. We did this for our BN2 and now the engine has excessive crankcase pressure and still leaks too much. Whether this can be attributed to the seal I can't say; I believe I would have checked the road draft tube for blockage but can't swear to it. A new thread just started re: drilling the rear main cap to drain the bearing. The kit we got--from BCS IIRC--recommended drilling but we didn't do it; the 100 crank is a known weak spot and compromising its support may not be advisable.

Austin Healey 100 Crank Failures. – Precision Sportscar

precisionsportscar.com precisionsportscar.com

A possibly better/safer solution would be to install a PCV kit. I'd pre-purchased a kit for my BJ8 but at overhaul my mechanic all but refused to install it. He said to stick with the PCV kit I had already, but he made some artful improvements. This car now uses a quart every 2,500 miles or so, which I can live with. I've acquired a well-engineered PCV kit for the BN2 and will be installing it as soon as I get some more round tuits.

Austin Healey 100 Engine Oil Leak Solution – Precision Sportscar

precisionsportscar.com precisionsportscar.com
 
Hi Bob and thanks for the info. I really have not done any research on rear seal kits which is why I asked the question.

Until reading BT7 owner's--and now your-posts re leaks despite having installed the rear seal kit I assumed that installing a seal was pretty much a 100% solution to the problem. It will be interesting to see what additional feedback gets posted.

I have one of the early finned cast AL valve covers--the pattern that Ray Juncal uses minus one fin--and thus do not have any vent pipe except for the road draft tube. As said, my car doesn't leak much oil out of the transmission drain hole so maybe I should leave well enough alone?
 
If your leak is just a few drops after a hard run I would leave it alone (your call, of course). The mods you have to make for a 100 are irreversible, the need for an additional drain is debatable, I've heard mixed results on the seals and a seal will wear and leak some eventually. There are also some who think the standard vertical drain pipe is too long as the end gets submerged and prevents drainage (I have no experience with that). When we first got our BN2/100M it would pee oil all over the floor after a run and we assumed it needed the rear seal. When we tore down the engine I found that the front seal on the gearbox was hard as a rock and, quite possibly, the source of most of the oil. If I was smart I'd have put 2+2 together and left well-enough alone. While you're in there, though, consider the copper pipe from the oil pump to the block, it's known to work-harden and crack. I installed a flex line from DWM and I see now Moss only offers a 'flexible replacement.'

My BJ8 pulls a slight vacuum at the filler cap at idle with a PCV--it has no source for fresh air that a true 'system' requires--but you can feel considerable pressure on the 100's filler. I have a stock valve cover with the vent that, since my car is a 100M vents to the CAB; it will make an ideal source for filtered air for a PCV system when I get it installed. It's kind of interesting, to me at least, that when emissions first became a hot topic, and the PCV system was one of the first, many raged that it was the devil. Now, hotrodders and others routinely install them not only to cut emissions and leaks, but it can keep your oil cleaner. The only downsides is a possibly dirtier intake. I put a catch can on my Mustang GT and it traps a teaspoon of oil or so every 1K miles; I've never replaced the valve on my BJ8 and it probably has 100K miles on it and the intake manifold was in good shape at tear-down.
 
Bob_Spidell said:
If your leak is just a few drops after a hard run I would leave it alone (your call, of course). The mods you have to make for a 100 are irreversible, the need for an additional drain is debatable, I've heard mixed results on the seals and a seal will wear and leak some eventually. There are also some who think the standard vertical drain pipe is too long as the end gets submerged and prevents drainage (I have no experience with that). When we first got our BN2/100M it would pee oil all over the floor after a run and we assumed it needed the rear seal. When we tore down the engine I found that the front seal on the gearbox was hard as a rock and, quite possibly, the source of most of the oil. If I was smart I'd have put 2+2 together and left well-enough alone. While you're in there, though, consider the copper pipe from the oil pump to the block, it's known to work-harden and crack. I installed a flex line from DWM and I see now Moss only offers a 'flexible replacement.'

My BJ8 pulls a slight vacuum at the filler cap at idle with a PCV--it has no source for fresh air that a true 'system' requires--but you can feel considerable pressure on the 100's filler. I have a stock valve cover with the vent that, since my car is a 100M vents to the CAB; it will make an ideal source for filtered air for a PCV system when I get it installed. It's kind of interesting, to me at least, that when emissions first became a hot topic, and the PCV system was one of the first, many raged that it was the devil. Now, hotrodders and others routinely install them not only to cut emissions and leaks, but it can keep your oil cleaner. The only downsides is a possibly dirtier intake. I put a catch can on my Mustang GT and it traps a teaspoon of oil or so every 1K miles; I've never replaced the valve on my BJ8 and it probably has 100K miles on it and the intake manifold was in good shape at tear-down.
Click to expand...
While you're in there, though, consider the copper pipe from the oil pump to the block, it's known to work-harden and crack. I installed a flex line from DWM and I see now Moss only offers a 'flexible replacement.'
------------------------------------------------------------------------------
I installed a flex line years ago after the copper pipe fractured while I was driving at speed. Luckily my eyes were on the OP gauge when it happeded--I literally saw the needle falling and was able to shut down with no damage. I also installed a red low OP warning light in the dash.
 
Bob_Spidell said:
Michael, Which kits are you considering? I've installed one and seen at least one other advertised, but they didn't seem to have much, if any, differences.

Note any kit AFAIK for the 100s requires machining the crank and some re-shaping of the rear engine plate. We did this for our BN2 and now the engine has excessive crankcase pressure and still leaks too much. Whether this can be attributed to the seal I can't say; I believe I would have checked the road draft tube for blockage but can't swear to it. A new thread just started re: drilling the rear main cap to drain the bearing. The kit we got--from BCS IIRC--recommended drilling but we didn't do it; the 100 crank is a known weak spot and compromising its support may not be advisable.

Austin Healey 100 Crank Failures. – Precision Sportscar

precisionsportscar.com precisionsportscar.com

A possibly better/safer solution would be to install a PCV kit. I'd pre-purchased a kit for my BJ8 but at overhaul my mechanic all but refused to install it. He said to stick with the PCV kit I had already, but he made some artful improvements. This car now uses a quart every 2,500 miles or so, which I can live with. I've acquired a well-engineered PCV kit for the BN2 and will be installing it as soon as I get some more round tuits.

Austin Healey 100 Engine Oil Leak Solution – Precision Sportscar

precisionsportscar.com precisionsportscar.com
Click to expand...
Bob Spidell said: "I've acquired a well-engineered PCV kit for the BN2 "
-----------------------------------------------------------------------------------
Bob--

What was the source of the PCV kit you refer to?
 
David Nock installed a rear seal on my BT7 about 25 years ago and my car still doesn’t leak any oil from rear of the motor. What minimal oil it does leak comes from the transmission. I have a stock engine set up with no PVC valve.
 
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