MSB Gearbox Under Pressure??

Post by **lwight** » Sat Jul 04, 2015 9:22 pm

I've got an MD17C turning an MSB gearbox. I notice that if I open the gearbox fill plug after running the engine, there's a poof; the gearbox is under positive pressure. Of course the crankcase is under positive pressure and we use that for ventilation. But why would the gearbox be under pressure?? Is it leaking past the seal? Is there a plugged air vent?
I'm very curious if this is typical because I can't seem to eliminate a small but persistent oil leak from the gearbox. It's coming from around the drain plug...
I'd love comments on both: the positive pressure and the leak.
Larry Wight
Albin 25 #2630

don123 · Post by **don123** » Sun Jul 05, 2015 8:29 pm

I would suspect a plugged air vent - That would account for both the pressure you're seeing when it's warmed up and probably the leak too. If the inside of the gearbox isn't vented, pressure will build up when it gets hot and when the lubricant is pressurized, it will be forced out somewhere . . . . a seal if nowhere else

Don

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MSB Gearbox Under Pressure??

MSB Gearbox Under Pressure??

Re: MSB Gearbox Under Pressure??