E28 Transmission leak

I just bought an E28 that had been on the hard for 13mos. I did an engine test which went very well. It started right away and we ran it for 5 minutes before shutting it down. One week later I noticed that the entire transmission fluid cavity had leaked out. The plug was tight with the seal washer intact. There were no signs of a leak prior to running. It is model Hurth HBW-50. Any experiences with this or ideas? Thanks. Jim, East Coast of Lake MI.

When refering to the plug are you speaking of the one on the top used to fill and check the level or the drain on the bottom?

Best,
Frank

P.S. Welcome to the exchange!

Hey, at least the engine runs well.
I'm assuming you meant the drain plug/washer was tight.
Did ANY oil come out when you removed the drain plug? If the output shaft seal failed there should have been SOME oil left, even if the tranny is sloped back at 5 deg. I would think.
You may have to pour some more oil in and observe. First wipe down the outside of the transmission real well so the leak can be seen (or felt, depending on access). Have a trouble light and a small mirror ready to inspect all sides and underneath.
Lake Michigan in December would suggest the boat is still on the hard and that's where the engine test was done. Correct? Was the transmission put in foreward or reverse during the test?
Was the boat used regularly prior to the layup?
Seems I have more questions than answers..........

Rob L.
Vancouver, E34

Reply to Lindaloo and Bayboss: The drain pluck was intact and there was zero fluid left when we removed the plug. It was tested mostly in neutral and a few seconds in fwd and rev. It had regualr use until put up in Sept 2009.

Maybe this is a stupid question, but did you check the bilge for transmission fluid? The reason I ask is that you didn't mention finding transmission fluid in the engine drip pan or in the bilge and the drain plug and washer were intact, which could lead one to think that the transmission may have been empty to begin with. Did you check the fluid level in the tansmission prior to the engine test?

I would replace the drain plug washer, fill with new fluid and run it again to see where it might be leaking...

mherrcat said:

Maybe this is a stupid question, but did you check the bilge for transmission fluid? The reason I ask is that you didn't mention finding transmission fluid in the engine drip pan or in the bilge and the drain plug and washer were intact, which could lead one to think that the transmission may have been empty to begin with. Did you check the fluid level in the tansmission prior to the engine test?

I would replace the drain plug washer, fill with new fluid and run it again to see where it might be leaking...

Click to expand...

I know that "talk's cheap" from way up here in the 3rd balcony.. but I like Mark's pragmatic approach.

LB

I'll go with Mark on this one as well. The only thing that I would do different is that once I changed all the plugs I would put in fluid and then wait a moment or two and check for leaks. Then I would run the engine and engage the trans. If the leak presents itself without the engine running and trans engaged then its a "static" leak that would indicate a crack or other leakage in the casing. If the leak occurs with the system in gear then the leak my be coming from a seal or other mechanical option. Not always the case.. but a starting point never the less.

Best & Good Luck,
Frank

Thanks for all your input. I flipped the drain plug washer, refilled and ran the engine for a while. No runs, no drips.....Jim G West Coast of Michigan.

It would be a good idea to check your tranny fluid every time you use it until you are dead certain it's not leaking anymore. I had a brand new ZF tranny that had just seen its first fluid change at around 40 hours of run time. After the change, all the new fluid leaked out the drain plug unnoticed and the tranny seized, ruining the unit & necessitating another replacement. The drain plug was tight enough to need a wrench to open it, and the washer was intact and free of marring or deformation. Its seat in the tranny was not deformed, and there was no cross threading. The mechanics I spoke to said that if even if the plug wasn't torqued to exact specs, if it required a wrench to loosen it then it should never have leaked. But leak it did, and had I been checking it every time until it proved it was holding its fluid, I would have saved myself a lot of work and nearly $2000.

Dan Morehouse
1981 E-38 'Next Exit"

Thanks Dan, I think that I'll replace the plug gasket for good measure.