Crankcase leak

Has anyone successfully stopped a crankcase joint leak from the outside? This is a drip near the drain plug on a 72...and no I don’t need the standard answer...just rebuild it.....well seal was used but I don’t think I would use it again, any creative suggestions appreciated!....

Maybe do everything you can to improve the breathing, to reduce pressure within the case. But won't help if it's dripping even when the engine's off.

Already has a Reed valve

Is it leaking from the split case line or the threaded drain hole?

Your engine to cradle bolts are tight? These do come loose.

Everything’s tight just rebuilt ,

It’s not the drain plug

Well I'm out of guesses. I used Wellseal between case halves and it worked fine. Both halves were perfect though. You could try J B weld spread around the area of the leak area but its getting into shady tree mechanics zone. IMHO

Don’t forget that an oil leak from anywhere on the engine will dribble down to the bottom, thus making it look like the source of the leak.

Have you throughly cleaned the engine and confirmed that’s where it’s coming from?

If your surfaces were good, and the Wellseal was correctly applied, and everything is tight, it really cannot leak. So if it is leaking from there, it has to be because one of those three things isn’t / wasn’t right…

Wash thoroughly with solvent. Use masking tape, tape off 1/4" on both sides of the joint, go well past the leak area (at least 3" overall) and trowel a thin coat of JBWeld.
Take the tape off while the JB is still wet.

concours said:

Wash thoroughly with solvent. Use masking tape, tape off 1/4" on both sides of the joint, go well past the leak area (at least 3" overall) and trowel a thin coat of JBWeld.
Take the tape off while the JB is still wet.

Click to expand...

Oh Shit. Hobot is so close. I can feel his....

Thats something what I would do! LOL

It’s all new 50 miles... JB weld will do it but too permanent for my liking ! Would have to grind it off someday!

Keep on keep'n on.
deal with it when you have too.
Cheers
T

JB weld, like most epoxies, softens quite readily with some heating from a propane or butane torch, to point where it can be scraped off with a blade or paint scraper.
Could also use the five min setting type, as that hardens less and does not adhere as well.
Other options, some low viscosity silicone sealant as used for window trim sealing might suffice to seal a minor leak. Certainly easy to the remove if needed.

Yamabond or other poly urethane gasket sealants might do it.

Clean surfaces as thoroughly as possible, brake cleaner etc. Tape off around area and try to force whatever is being applied into seam.

J B weld.... used for many things.
for the crank seals. search the forum.
Etc. etc.

Normally crank cases seal pretty good with any sort of sealant that has been used, my crank cases got a large pool of oil under it after a ride and found the oil next day when it was sitting on the lift table over night, not a great big pool of oil but enough to find out where it was coming from, cases were sealed with yammybond when put together 14 years ago but found 3 engine mount bolts were lose tighten them up and the crank is sealed up tight again and no more leak, that was 5 months ago.
Like what others have said oil leaks can travel from anywhere you just got to follow the leaks and fix where they are coming from, check your oil lines, base gaskets even oil tank leaks can travel down the lines and onto the crank cases, so might not be your crank cases at all, seepages can also pool up and look like a oil leak after sometime, my motor has always been oil tight from new but sometimes do get seepages and gaskets can fail even after rebuilds and why shake down rides are important after any rebuilds and re torquing things down after a few miles, you just got to clean the motor, maybe use some talcom powder and hunt up the source of the leak, could just be a simple O ring or copper washer or a failed gasket, its all part of new motors/rebuilds always something not sealed right and that goes for any motors.

Ashley

I've had good luck finding leak sources by very thorough cleaning followed by a spray of foot powder like Desenex. More or less like the talcum powder suggestion above, but the spray helps to overcome gravity.

When the motor was getting rebuilt did you have the crank cases pressure cleaned? if so by aggressively cleaning the outer surface you may have opened up a porous area. I believe that slightly porous heads and cases were fixed at the factory by 'vacuum' painting. This should be an easy job for the likes of JB Weld.