2GM transmission leak

[lockie]

Hi all;


It should be a really simple thing to replace the oil seal on the output shaft and have it leak-free, right? Well I've replaced it a couple of times now and the bloody thing still leaks. It's definitely clean gear box oil, not black engine oil. It's not coming from the shift lever assembly or the dipstick or the drain plug.



It's a Kanzaki KM2A box and I just can't get my head around why what should be so simple is so hard to fix.



It has the correct type and quantity of oil, correct Yanmar seal carefully pressed in with non-hardening sealer, flange boss shined up like a mirror, new O-ring and sealer under the flange nut. But it's still leaking. Why?



One thought is that the recess in the housing is a millimetre or two deeper than the width of the seal, so maybe pressing it in all the way instead of leaving it flush with the housing face is the problem?


Cheers, Graeme

[Engine man]

Check the simple things first.

Synthetic oil is extra slippery, and may cause leaks in older machinery. What exact oil is installed?

Is the unit overfilled? Is the vent clear? Is the seal installed backwards? Is engine alignment correct? Can alignment be maintained? Are the flexible engine mounts collapsed? [ very common on older Yanmars ]

Is the prop shaft straight, or bent? Is the shaft coupler rotating concentrically with the prop shaft? Is the prop shaft wiggling while underway under power? What type of prop is installed? Is the shaft zinc causing a shaFT IMBALANCE? iS THE TRANS CORRECTLY MOUNTED TO THE ENGINE? Are all engine mounts correctly secured to the engine, and then to the bed? Do you have the correct flexible mounts installed according to the manual? Is the flexible coupler damaged of incorrectly installed?

Contact me off list if you need any clarifications.

Joe

Originally Posted by lockie

Hi all;


It should be a really simple thing to replace the oil seal on the output shaft and have it leak-free, right? Well I've replaced it a couple of times now and the bloody thing still leaks. It's definitely clean gear box oil, not black engine oil. It's not coming from the shift lever assembly or the dipstick or the drain plug.



It's a Kanzaki KM2A box and I just can't get my head around why what should be so simple is so hard to fix.



It has the correct type and quantity of oil, correct Yanmar seal carefully pressed in with non-hardening sealer, flange boss shined up like a mirror, new O-ring and sealer under the flange nut. But it's still leaking. Why?



One thought is that the recess in the housing is a millimetre or two deeper than the width of the seal, so maybe pressing it in all the way instead of leaving it flush with the housing face is the problem?


Cheers, Graeme

[Robert_Pegasos]

Old thread, I know, but did you get the oil leak fixed? What turned out to be the cause? I have the same gearbox with the same problem ...