351m oil leak
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Elder User
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From: Afton NY
351m oil leak
i have a 77 highboy with a 351m it is a low milage motor. off the road since 85. has 65000 original miles. i drive it daily. has never had a leak other than power assist cylinder. well other day i went to work.50 miles came home and parked as soon as i shut it off oil poured out of bell housing and does every time i drive it now. any ideas ? someone tell me a cheap fix before i toss an fe block in it.
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From: PacNW
The first thing I'd check would be the oil pressure sending unit on the top, back of the motor behind the intake manifold. I'd also check the valve covers & rear of the intake. Always start at the top and work your way down when trying to diagnose an oil leak...it's a gravity thing.
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Elder User
Joined: Jan 2004
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From: Afton NY
changed sending unit. definatly is coming out of the bellhousing. is motor oil losing 2 quarts a day. changed oil filter and it slowed up but didn't stop. thought rear main seal but never had or heard of one go that fast. from nothing to 2 to 3 quarts a day. going to try a rear main seal this weakend. is it possible for freeze out behind cam to fall out? am i going to be able to sneak the rope seal out w/out pulling trans?
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From: chicago burbs
anything's possible, but it sounds like a rough job to me. i have always pulled the engine to do work inside the pan. there are a lot of guys that do crank/bearing/seal work in the vehicle but i like to know that i'm making a good seal, not doing more damage than good, and not going to have to do it again. it is also possible that the rear cam plug has deteriorated and is leaking. do you know if the engine has been worked on before in any area that may be the source of your leak? to put an FE in it you'll have to change the bellhousing or the trans, and maybe the engine mount perches?
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Junior User
Joined: Oct 2004
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From: NE OK
i have a terribly similar situation on my Hiboy (77-351M) and i have already replaced the rear mainseal with the neoprene molded seal, but i dropped the pan (had approx 1.5 inches to work in) scraped the surfaces, installed the neoprene seal and new pan gasket with permatexwith front and back molded seals; and over the last three weeks it has steadily increased leaking oil to now about a quart or two everyday. my question is; tell me the best way to hoist the engine (lift eyebolts w/chain? and where is the best stud holes to use?) theres gotta be a better way... thanks for all the great advice.
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From: chicago burbs
i use the threaded holes in the front and back of the heads, with a bolt threaded fully in and a washer on it through a chain. the bolt doesn't have to be tightened, but they shouldn't be excessively long either. one bolt in the drivers side head and one bolt in the passengers side head, so the chain goes on a diagonal across the engine front to back. you might even want to use spacers(washers) between the head and the chain so that the valve covers aren't damaged, or remove the covers. don't use your alternator and power steering bolts! they will get bent! go to the hardware store if you have to! there are also lift plates made for pulling engines, they use the carb bolts to screw into the intake manifold. i think most of the 335 series engines had lifting brackets on the exhaust manifolds too? just hook to 'em.
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