Rear oil seal question, what to choose

[Michael Ponsano]

1949 MG TC #9864

9864's engine was rebuilt about 6 years ago. At the time the crank scroll was filled and polished to accept the Chevy 350 oil seal.
The motor was run up and set aside about and has since been dormant. I am tearing down the engine again for a number of reasons and was wondering what was the success of the Chevy seal over the Moss kit. The engine was not run long enough to determine the success of the Chevy seal and am thinking to change over and just use the Moss part.

[Steve Simmons]

I haven't done the Chevy seal but I know people who have. From what I've been told, they are about equal in reliability. Both are fiddly to get right. Both will leak a lot if not set up just right, and conversely both will seal nicely if everything is in order.

David Edgar of TCMG wrote a few times on the Chevy seal:

http://www.tcmotoringguild.org/techinfo ... r-seal.pdf
http://www.tcmotoringguild.org/chassis/06NovMidget.pdf
http://www.tcmotoringguild.org/chassis/06OctMidget.pdf

[stephen stierman]

I would be very tempted to run the Chevy seal if I were pretty sure that it was done per the instructions that Steve references. It seems to me that the Chevy seal installation if done correctly has much less margin for error than the installation of the Moss seal. When I rebuilt the engine in TC 2911, I used the Moss seal and thought I was careful when installing. Apparently I was not and it leaked profusely. Suspect that I should have used the speedy sleeve and perhaps needed to clearance the flywheel which wasn't. Ultimately I went back to the slinger and while it puts a couple of drops down when the engine is shut off, it does not seem to leak while running. I might suggests that if the car is assembled that you might build a rough engine support stand as I did so that you could run it while it is out of the car to see how it works. As we know pulling an engine out of an assembled TC is rather a PIA.

[Duncan M]

I think the beauty of the original slinger is that it lasts indefinitely. Add a clever diaper and it will not leak on the floor on shutdown.

[jddevel]

As the scroll principle I believe was used on the crankshafts of other vehicles manufactured in the early years is there a record of other vehicles having the same problem or is there a specific difference with the MG crankshaft.

[Michael Ponsano]

Thanks Stephen, Good idea on the engine support stand. For simplicity I think I'll run the engine up in the frame as its still stripped of all other components. Good point on the Chevy vs Moss too, I am going with the Chevy and see how it works. I was very careful on its assembly. I'll post my results with pictures in the coming future. If it dose not, Ive got the Moss kit on the shelf to change over to.

[stephen stierman]

As the scroll principle I believe was used on the crankshafts of other vehicles manufactured in the early years is there a record of other vehicles having the same problem or is there a specific difference with the MG crankshaft.

Yes, there were lots of vehicles that used this or a variation of the scroll seal. Most all of them tended to leak a bit, some more than others depending upon how worn and how much oil comes off the rear main bearing that the slinger has to deal with. One advantage of the design of the the XPAG is that there is some adjustability in how close the alloy thrower is positioned to the crank. The closer you get it, even a slight touch will limit the oil coming off and draining to the outside. Many of these slingers in other cars cannot be adjusted and hence the market for replacement with lip type oil seals, some working better than others.

[Duncan M]

jddevel wrote: ↑Tue Feb 09, 2021 5:12 am
"As the scroll principle I believe was used on the crankshafts of other vehicles manufactured in the early years is there a record of other vehicles having the same problem or is there a specific difference with the MG crankshaft."

Don't forget the TC stock differential has the scrolls at input and output. Works fine if properly maintained, though the scrolls at pinion cap will allow in tiny amounts of dirt, etc. Therefore, more frequent oil changes. If the pinion bearings were/are properly tended to, the scrolls on the cap will last forever.

[stephen stierman]

jddevel wrote: ↑Tue Feb 09, 2021 5:12 am
"As the scroll principle I believe was used on the crankshafts of other vehicles manufactured in the early years is there a record of other vehicles having the same problem or is there a specific difference with the MG crankshaft."

Don't forget the TC stock differential has the scrolls at input and output. Works fine if properly maintained, though the scrolls at pinion cap will allow in tiny amounts of dirt, etc. Therefore, more frequent oil changes. If the pinion bearings were/are properly tended to, the scrolls on the cap will last forever.

Funny thing about that pinion seal on the front of the diff, when I back the TC up my drive which is a slight hill, I get a trail of gear oil drops. The nose of the diff is lower than the rear and things are turning in reverse, thus instead of throwing oil back into the diff, it gets thrown out the front..........

[ROGER FURNEAUX]

The scroll on the diff. pinion shaft can work reasonably well it everything is in good condition. BUT any dust or grit will get drawn into the front bearing, shortening its life, and also scoring the drive flange boss. Over the years I have rebuilt a lot of diffs, and very often this scoring is so bad that I have to machine them down to work with a new pinion cap lip-seal.

And of course we all know how ineffective the scrolls at the axle ends are! They can work when new, but the halfshafts whip so much that they soon wear out. Which is why I came up with the idea of bearing locking nuts with lip-seals in them, which solve the problem of oil getting onto the brakes.

The diff. oil is thicker and does not get as hot as engine oil, which has an even greater tendency to escape!

Roger Furneaux