125 Power Plant leaking From Front Seal
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Category: Allis Chalmers
Forum Name: Farm Equipment
Forum Description: everything about Allis-Chalmers farm equipment
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=165109
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Topic: 125 Power Plant leaking From Front Seal
Posted By: WF owner
Subject: 125 Power Plant leaking From Front Seal
Date Posted: 17 Oct 2019 at 7:30am
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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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Replies:
Posted By: Alex09(WI)
Date Posted: 17 Oct 2019 at 9:00am
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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.
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Posted By: mdm1
Date 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.
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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!
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Posted By: CrestonM
Date Posted: 18 Oct 2019 at 9:15am
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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.
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Posted By: Sugarmaker
Date 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
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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.
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Posted By: mdm1
Date Posted: 18 Oct 2019 at 10:07am
I did install a speedi sleeve on the shaft. Maybe I should have Creston eyeball mine.
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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!
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