125 Power Plant leaking From Front Seal

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   A friend of mine has a (topsoil) screening plant with an AC 125 cubic inch (B, C, CA) engine. He says it runs very well, but it recently started leaking badly from the front crankshaft seal.
He said it doesn't seem to have much blowby. What would cause the seal to go? 

How hard is it to change the seal? Do the main bearings have to be loosened to get a new seal in? Any tips on an easy way to change the seal?

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WF owner Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Joined: 12 May 2013 Location: Bombay NY Points: 5025	Post Options Post Reply Quote WF owner Report Post Thanks(0) Quote Reply Topic: 125 Power Plant leaking From Front Seal Posted: 17 Oct 2019 at 7:30am
	A friend of mine has a (topsoil) screening plant with an AC 125 cubic inch (B, C, CA) engine. He says it runs very well, but it recently started leaking badly from the front crankshaft seal. He said it doesn't seem to have much blowby. What would cause the seal to go? How hard is it to change the seal? Do the main bearings have to be loosened to get a new seal in? Any tips on an easy way to change the seal?

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Alex09(WI) Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Joined: 15 Mar 2012 Location: CECIL WI Points: 1751	Post Options Post Reply Quote Alex09(WI) Report Post Thanks(0) Quote Reply Posted: 17 Oct 2019 at 9:00am
	Its best to remove the front cover off the engine to change the seal. I beleive there are 2 different OD's of the seal, make sure you get the right one. Some seals don't have the spring to hold the lip to the shaft. Also when reinstalling the front cover, you must align the cover so the crankshaft is centered coming through the seal. The holes are drilled a bit larger so that's possible. Seals go bad because contact with oil will eventually harden the rubber, especially ones that are not submerged in oil, thus leading to oil getting past.
	www.awtractor.com A&W TRACTOR 920-598-1287 KEEPING ALLIS-CHALMERS IN THE FIELDS THROUGH THE 21ST CENTURY

mdm1 Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Joined: 12 Sep 2009 Location: Onalaska, WI Points: 2678	Post Options Post Reply Quote mdm1 Report Post Thanks(0) Quote Reply Posted: 17 Oct 2019 at 9:07am
	Pay attention to what Alex said about aligning the cover! I measured the opening in the cover and took the cover with when I ordered the new seal. I wasn't aware of that and so now I get to do it all again. Just a question. Is my seal now no good? I only have maybe 2 hours on it. I planned on putting in a new seal anyway.
	Everything is impossible until someone does it! WD45-trip loader 1947 c w/woods belly mower, 1939 B, #3 sickle mower 1944 B, 2 1948 G's. Misc other equipment that my wife calls JUNK!

CrestonM Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Joined: 08 Sep 2014 Location: Oklahoma Points: 8455	Post Options Post Reply Quote CrestonM Report Post Thanks(0) Quote Reply Posted: 18 Oct 2019 at 9:15am
	Depending on what year the engine is, it may not have had much of a seal at all to start with. The older ones (like my '42 B) have a spiral groove cut into the crankshaft, and the seal is something like layers of cork that act as a seal. The idea of the groove, I believe, is as it turns, it helps push oil back into the engine, to keep it from leaking out. When I resealed mine, I found out it had the smaller outside diameter seal, but I put the updated larger one in. Just made the hole bigger with a Dremel tool. To keep the spiral groove from eating the new seal, I cleaned it well, applied JB Weld to the groove, let it cure, then sanded it down to be flush with the rest. As far as centering? I installed the seal in the cover (off the tractor), then put the cover back on over the crankshaft, eyeballed it, and tightened it down. That was in 2016, and it hasn't leaked yet. Edited by CrestonM - 18 Oct 2019 at 9:17am

Sugarmaker Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Joined: 12 Jul 2013 Location: Albion PA Points: 8524	Post Options Post Reply Quote Sugarmaker Report Post Thanks(0) Quote Reply Posted: 18 Oct 2019 at 9:49am
	WF, You should not have to do any thing to the main bearings, But I have never worked on one of these. Going by WD type units. The human eye can see .005 inch, so Crestons method might work about as well as a mechanical alignment. I have used a drill bit shank as a gage to go around and check the gap for the seal. Mdm1, I would do a good visual on your seal might still be OK. Also I have installed speedi sleeves over the groves in the crank. Regards, Chris
	D17 1958 (NFE), WD45 1954 (NFE), WD 1952 (NFE), WD 1950 (WFE), Allis F-40 forklift, Allis CA, Allis D14, Ford Jubilee, Many IH Cub Cadets, 32 Ford Dump, 65 Comet.

mdm1 Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Joined: 12 Sep 2009 Location: Onalaska, WI Points: 2678	Post Options Post Reply Quote mdm1 Report Post Thanks(0) Quote Reply Posted: 18 Oct 2019 at 10:07am
	I did install a speedi sleeve on the shaft. Maybe I should have Creston eyeball mine.
	Everything is impossible until someone does it! WD45-trip loader 1947 c w/woods belly mower, 1939 B, #3 sickle mower 1944 B, 2 1948 G's. Misc other equipment that my wife calls JUNK!