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MG TD TF 1500 - R/M Main Seal Conversion

I'm in the process of rebuilding an XPAG engine from a '51 TD.
Since it had a fairly serious oil leak from the rear main (it was the seal, not the rear cam core plug), I decided to use the highly touted "Al Moss Rear Main Seal Conversion Kit".
I have followed the step-by-step, very comprehensive, instructions, and discovered that the seal retainer sat "proud of the crankshaft flange by over 1/8". This meant that the flywheel is pressed up to the back side of the seal retainer to the point where it prevents rotation of the crank.
In the end I called Moss Mtrs., who in turn put me in touch with Lawrie, who is the fellow that worked with Al Moss on the design of the seal.
He suggested removing the gasket that had been required to obtain clearance between the R/M cap and the seal retainer, and would thus allow the seal to be positioned further forward. Having done that I found the problem resolved. The seal itself however, when mounted in the retainer, sits "proud of the retainer, by 3/32", which means the flywheel would rub against the back of the seal, always assuming that the crank would even turn,
Lawrie suggested that if the retainer was taken to a machine shop, and the "step" on the mounting surface for the seal was machined down, the seal would sit further forward and thus not contact the flywheel.
He is right, but seating the seal forward enough to fix the problem means that the lip of the seal no longer rides on the crankshaft flange.
I'm hoping someone else out there has had a similar problem and found a resolution. If not, it means that I'll have to scrap the very expensive conversion kit and go back to the original XPAG seal.
Help!!


JR Ross

Hello JR. I have found that on a couple of engines the seal did not sit on the crank flange and the flange was too rough and the lip of the seal would get eaten within a couple rotations of the crank. Ipersonally think that this is where the problems come from with the moss kits that leak. What I hav done to three engines is to put a speedy sleeve on the crank shaft flange with it protruding from the flange toward the front of the engine far enough so the seal has a surface to ride on. The current engine in my car has been in for quite a few years(over ten years) of going to events and Gof West all the time.

Butch
R Taras

I have line bored my engine to get .001" or less main bearing clearance.
Hand fitting of the oil thrower is needed to get a no interference fit.
After this was done I have no oil leaks with the original from the factory set up.
But it did take me a few times of removing & reinstalling the oil pan to get from a quarter size drip to ZERO leaks!
Len Fanelli

I had to install a speedi sleeve sitting just a bit forward for the seal to engage.

R&L engines will line-bore and hand fit as Len does and claims very little leakage.
JE Carroll

JR

You have my full commiserations on this subject, if you search the archive for posts made by me on this subject you will note there are multiple issues to fit the rear seal conversion.

XPAG engine and associated component dimensions vary considerably.

You have exactly the same problem as I encountered. The solution was to machine the fly wheel so that it fitted further forward and fit the speedi sleeve in a position to provide the seal with a full running surface.

In hind sight I would never would have fitted this conversion. There are better options available, only issue is that it means having to remove the crank and have it machined.

The bonus in your favor is you have the motor out of the car.

Graeme
G Evans

jr, i did the same as butch 5 years ago when i did my rear main..a speedi sleeve riding just forward on the flange..not a drop in thousands of miles. no machining, no fuss.. regards, tom
tm peterson

I think the Speedi Sleeve idea would work, but I'm thinking that where the seal lip would ride, would be on an "overhanging" part of the sleeve and unsupported (3/32"). Is this not a problem????
JR Ross

Hello JR. You are correct that the seal would run on the unsupported portion. I can say that I have not had a problem with this. The sleeve is thick enough to support what little pressure there is from the seal. Also the sleeve has the correct surface finish for the lip to ride on. I also needed to grind off the part of the dowel pins and flywheel bolts that protruded thru the crank flange. I also put rtv sealant on the threads of the bolts and on the dowel pins before I inserted them since they are now exposed to the oil.

Butch
R Taras

Once again; Thanks to all that responded to my call for help.
JR Ross

not that Butch needs a second... but the seal on mine also rides on the unsupported portion of the sleeve. regards, tom
tm peterson

This thread was discussed between 23/01/2014 and 25/01/2014

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