SMD D264 Rear Main Seal

The rear main wasn't leaking badly, but the front transmission seal was. I decided to split the tractor and fix them both, plus the clutch condition was unknown so I could look at that too.

The rear main replacement is what I have questions about. The crankshaft has a spiral groove, the seal was felt, and the retainer is apparently aluminum as it's aluminum colored and fails a magnet test. I've seen the term "white metal" but not sure I know what that means.

The seal retainer bolts were barely finger tight. I mean that literally, as using a regular 3/8" ratchet, it took pretty much zero force to start them out, no "breaking loose" necessary at all.

So, my questions...

Is there a better retainer? Do I need a better retainer?

What is the torque spec for the retainer bolts? Dry bolts in a dry hole? Anti-sieze in aluminum holes? Lock-tite anywhere?

I have the oil pan dropped down far enough to easily disassemble the rear main. I'm assuming it can be properly sealed (new gasket, proper cleaning of course) after I put the tractor back together and get the splitting stand out of the way?

You want to get seal and retainer of a late D264 or
D281 engine. It uses a modern lip seal. You can scan
the CaseIH web site it look under a farmall 450
Diesel.

Andrew

The words White Metal mean that it is some alloy of zink, tin, lead, cadmium, bismuth, and other low melt temp metals. The metal is often weak, brittle, or marginal for use in stressed structural places. If yours is flat, it is because it was not overtightened the last time it was serviced. There are many that show serious warpage and failure to. seal as a result of treating it like flywheel bolts (just kidding a little). If yours is flat, I would be thankful! Lay it on a piese of glass to check it. If you find a newer series unit, (check the location of the seal lip to be assured it is not running on the spiral grooves! And that there is smooth polished crank under the lip)
If you cannot find one, and yours is flat, I would use it. Just remember not to reef it down. Jim

I don't need a piece of glass to tell, it's warped!

What are my options? Not much room between the end of the spiral groove and the flywheel flange, and half of that is discolored like it was outside the felt seal. Maybe it's OK, but how to clean it up and make sure?

I have a cast iron one with a lip seal off another engine, but that seal is dead center on the spiral groove in this engine so it's no help.

Well, I went through this two winters ago and it was a major failure. I found a metal retainer from a 450d and used a felt seal. You can't use a rubber seal with the spiral groove from what I have heard. Common sense tells you the groove will tear up the seal. You can't use a felt seal without a spiral or it will leak. That is just common sense.

So I soaked a felt seal in oil and used the metal retainer. All was well for about three hours and now it leaks like a sieve. The retainers appeared to run in the same spot. The crank was smooth from what I could tell. All that and it leaks more than it did with a warped retainer and a 50 year old seal. The only thing a lot of guys say is that it might have spun the felt. Was this because I used the new style retainer with felt??? Maybe

Sorry, no answers in all of this because I haven't had the time and patience to split the tractor again. If you don't mind a hijack, do I have to split an MD with the small clutch to drop the flywheel?

I use a torque table on all bolts that don't have a specified torque in the book. If I remember correctly for a 3/8 NC grade 5 bolt it is 27 ft lbs.

Sorry, yes. Jim

Three ideas:
Clean the crank at the grooves until it is bare metal carb cleaner dry. Use devcon, or JB weld to fill the grooves. Use a thin sheetmetal strip wound around the crank and hose clamped down to force the JB weld smoothely into the spiral. Then use fine 400 paper to smooth excess JB.and polish to level with the metal.

Second idea. Make new felt fit the retainer better by wrapping it as needed to keep it from moving, and adding to its compression on the crank. I would use a 5 minute epoxy to keep it straight.

Third is to ask Chicago Rawhide, or National if they have a two piece seal that could be placed such that it does not touch the spiral. Even a backwards facing seal might do well. Jim

IH instructions when installing the lip seal and retainers on engines with the groved crank, was to just dull the sharp edges on the groves before installing seal.

Use the felt. It should look oversized and have to
be forced into place without cutting any of it off.
Soak it good either before or after you get it in
the retainer. Try to square up that crooked retainer
best you can and then use a high temp silicone
gasket maker along with the gaskets to take up for
imperfections. Should not be a big deal. Back of
the block is a good flat surface to check it on.

(quoted from post at 22:06:37 06/03/12) Use the felt.

Click to expand...

I think this is the winning answer. This tractor has been here for 30 years, engine rebuilt right after it got here. Granted, it hasn't been used hard, but the rear main was not the primary reason to split it either. In fact, the evidence on the back of the block and on the flywheel makes me wonder if it was leaking at all. Except for the education, I think I'm sorry I pulled the seal retainer.

It appears there's two issues at play here, the felt seal as compared to more modern lip seals, and the mating surface of the seal retainer to the engine block. I believe the felt seal was good enough, and I hope I can properly install a new one. I also believe in modern RTV sealants and their ability to help stop the oil at the mating surfaces.

This forum is a great resource. I'm a few days away from reassembly so other opinions are welcome, but I think I know what I'm going to do now. Thanks to all.