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Rear Main Seal Leak with Moss Retrofit

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Chad Donner

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Has anyone continued to have issues with a rear main seal leak with the Moss main seal retrofit?

I haven't started the car yet, just primed the pump and cranking it over with the starter and i notoced a couple days later i had drips coming from the bell housing.

Is it possible that the drain tube off the bearing cap sitting below the oil level is causing oil to back up into the rear main seal cavity? ie..the head pressure of the oil draining from the bearing isn't enough to overcome the surface tension of the oil with the drain pipe below the oil level?


Thoughts?

I'm gonna try to post a picture as to what i am thinking about the drain pipe.
 
Rear Bearing.jpg
 
Is the car all back together or is the tranny still out? Is it leaking from the area of the rear main cap or is it indeed leaking from the bell housing? If the latter, it could be the trans.

Mine leaked from the vertical joints on either side of the rear main cap until I smeared the joints with Permatex Aviation Form-A-Gasket.
 
I kinda gave up on this leak. I too put in the improved seal only to have the leak recur around the cork gasket inserts. I tried putting a 0.004 stainless cover and sealant over the cork. It lasted for a year or so but then oozed oil again. Too much work to try something different.
 
There is no oil in the trans yet so I know it's coming from the engine, however, it is coming from the bell housing side of the rear engine plate. I used hylomar on all the joints and filled the verticle joints on the bearing cap with rev in lieu of the felt plugs. Not sure if the seal needs a break-in period, but I have not ran the engine yet and just cranked it over with the starter.
 
Chad Donner said:
Has anyone continued to have issues with a rear main seal leak with the Moss main seal retrofit?

I haven't started the car yet, just primed the pump and cranking it over with the starter and i notoced a couple days later i had drips coming from the bell housing.

Is it possible that the drain tube off the bearing cap sitting below the oil level is causing oil to back up into the rear main seal cavity? ie..the head pressure of the oil draining from the bearing isn't enough to overcome the surface tension of the oil with the drain pipe below the oil level?


Thoughts?

I'm gonna try to post a picture as to what i am thinking about the drain pipe.
Click to expand...
An improperly sealed rear engine plate gasket around the rear of the camshaft will give you a signifcant leak!!
 
I had a leak on the cam before i took the engine apart so i was trying to be sensitive to that area. I know the RTV made it all the way down, i held the caps slightly up off the block and pumped them full until i saw it come out the bottom then i drove the cap home.

The one thing i didn't think about are and back plate bolt holes that are open to oil, do you know if there are any?

I gonna try to see if i can get my hands on a boroscope and take the starter bendix cover off and see what i can see...
 
Pretty sure it won't be the rear seal kit if it leaks while cranking on the starter motor. Did you have the oil gallery plugs out? Did you run a file over all gasket surfaces to check for burrs? I have a leak that drips from the bellhousing but it is actually coming from the cylinder head and sneaking down the back of the engine. Andy.
 
Some more thoughts:

If there's a problem with the pan gasket or the little cork piece at the rear cap, you can solve that in situ. Those would be leaking down the front of the carrier plate and not inside the bell housing.

Everything else is going to require you pull the trans. Even if you see the problem with a bore scope, you'll still have to pull it to fix it. Which will be easier at this point than when you've filled it with oil.

The other thing you may have done is drilled through the block with one of your mount screws for the moss kit.

If properly installed, the Moss kit isn't going to leak any more than your original setup did.

Regarding the situation in your picture and the mods contemplated: if this were a problem, the engine would have been modified long ago and/or it would be common knowledge that it needed to be done. Are you sure this pipe is open and does it go up to a matching hole in the bearing?
 
I got a little closer look today and it does appear that the oil is coming down on the front side of carrier plate, so it may be the little cork piece. I didn't use the cork however, I used a bead of silicone instead. The front appears to be holding, maybe just not the rear.

Side note, I now have oil seeping from the outboard most head nuts around the threads at the very front and rear. Do these pass through an oily alley, should I have used sealant on these studs?
 
I'd like to hear if anyone has solved all the oil leaks on their Healey. I have leaks in four or five places. I've installed British Car Specialist rear main seal. I've lived with mine for 33 years. Used up a lot of old newspaper and cardboard. Oil is cheap and as long as you check regularly, no harm will come to engine or transmission. Worrying about it will age you prematurely. Just live with it, is my advice...
 
My car leaks a drop a week or so from the rear main seal area; none from the front seal and none from the trans (toyota).

Front pulley & cover has speedi-seal and hylomar on both sides of gasket. Aluminum pan with hylomar on both sides of pan gasket; small cork piece carefully trimmed to size & coated with hylomar. Two felt plugs in place in rear main cap. Moss seal kit with seal pinned in place see: https://www.pbase.com/stevegerow/image/91637859. This permits spring side of seal to face toward engine. Moss seal carrier sealed together and to block with permatex aviation form-a-gasket. Area around camshaft also sealed as are vertical joints in rear main cap - see picture in previous posting above.

This setup has held for four years.

Am running pcv valve which I believe helps keep oil from forcing out rear seal.
 
Rick and Steve: So, to stop leaks, use Toyota transmissions and Ford engines....
Thanks for the info!
 
I wanted to thank you all for the feedback...I snugged up on the pan in the rear a little. I plan on getting it fired up this weekend after i get my headers back from Jet-Hott today:smile:

I'll see how bad/tolerable things are after i get it running.

Any thoughts on the head studs leaking?
 
The first time I rebuilt my engine and started it up I had a bad leak at the rear of the engine. I almost had a heart attack. I thought it was coming from the rear main. Turned out it was leaking around the back of the rocker cover. I don't remember leakage from the rear main ever being a significant problem, and in view of all of the above it seems questionable whether it is worth the trouble to install the extra seal. Besides a little oil blowing back under the frame gives it a little rust proofing.
 
I installed a rear oil seal some time ago, it did significantly reduce the oil seepage but not completely. However, now that I have taken the engine out a for refurbishing I can see that there has been some seepage at the bottom of the aftermarket kit, so must pay special attention to that when I put it all back together again.

:cheers:

Bob
 
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