crank seals

brianbailey440

brianbailey440

Member
Joined
Jan 22, 2012
Messages
379
Age
54
Location
berlin n.h.
ok here goes. i bought a used engine that lost a piston on the stator side and was rebuilt with 1 used cylinder, 3 new pistons and new rings.i put it in, and 3 laps around the parking lot i lost a ring.so i took it apart, and found the ring jammed into the cylinder on the other side from where it broke.it cracked the cylinder and it was burning antifreeze, so i put oil in there to soak the rod bearing.i was going to just put my old top end on it because it was fine, but the oil is leaking past the seal where i filled it with oil.my question is, is there a spec for pressure testing crank seals on a red head engine ???pressure or vaccum test ???i plan on putting the cylinders back on and the head and blocking the carb boots to either pressurize or do a vaccum test on the seals but i cant find a spec for this.can anyone tell me what the spec is ???
 

its a real bummer when you put an engine in that someone tells you is good to go, and then you find out its not after you install it.i want to be able to test the seals according to spec before i have this problem again.this could help lots of people from having the same issue as im having right now.ill never put one in again without testing the crank seals before an install.just make more sense to test it, otherwise you cant be sure that it wont blow up on the first ride.anyone know the spec on the crank seals ???
 
Oil will travel from cylinder to cylinder in the bottom end. It is the oil that actually makes the seal. If your concerned about the outer seals, most likely where the problem is anyway, just pop the clutch and flywheel off and inspect the seals. Any oil seeping out is a dead givaway
 
Throttle Junkie35 said:
Oil will travel from cylinder to cylinder in the bottom end. It is the oil that actually makes the seal. If your concerned about the outer seals, most likely where the problem is anyway, just pop the clutch and flywheel off and inspect the seals. Any oil seeping out is a dead givaway
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i couldnt tell when i got the engine,it was a top end rebuild, and was nice and clean. the guy told me he had 1000 miles on it, but when i took it apart, there was no possible way that it had any miles on it.no color on the pistons exept for the time i ran it.so i took his word for it and put it in,only to break a ring because he probably didnt line them up rite when he put it back together, or check the end gap. soo i put oil in that rod area to soak the rod bearing because it cracked the cylinder when the ring caught and broke and it was burning antifreeze. the next day i noticed oil coming out of that crank seal.it probably needs new seals, but thats not the point, i want the spec to test them soo i dont have to wonder if seals are good when i swap another engine.does anybody know the spec for testing crank seals in a red head engine ???
 
About 4 or 5 years ago, I rebuilt a redhead, and someone gave me the specs in one of the posts. It might have even been before I rebuilt it, and was having trouble with the PTO side running really rich all the time. If so that would have been about 6 years ago. I couldn't find it, but I know it was there. I don't remember what the spec was either.
 
I think it's called a leak down test. Where you seal all the ports and pressurize the cylinders to something like 5psi, then let it sit and see if it stays at that. But i don't remember the exact procedure...
 
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