Vacuum testing Johnson Venom gear case

[dentpusher]

Sorry, mobile version does not specify which arena you are in... I moved it to Johnson but any input is appreciated!

Hello all, new to forum.

I have a 98 Johnson Venom 200 that got has some cloudiness in the grease after 3 years service, about 15-20% of the grease had light milky haze to it. I performed a pressure test and it holds 6 lbs pressure indefinitely, over night. Hooked up vacuum and I get a 1 inch loss of vacuum in 5 minutes. My question is, is there an acceptable rate of loss or should it hold vacuum indefinitely like it does pressure. Or is there a specific rate of acceptable rate of loss like 1 inch per minute?

Thanks for the help,
Dave

 

[kghost]

Most gear cases should hold 15 psi for several minutes.

OMC recommends I believe 18 psi for 2 minutes. That is a bit high so I use 15.

Vacuum testing is a bit tricky. You should be able to achieve ~ 6-8 inches of Hg on a gage. If not then you have a leak.

So how many inches of Hg did you pump to?

As far as time for vacuum.............I would say 2-5 minutes is good.........if it leaks down then you need either soapy water or a good ear.
STart by moving prop shaft see if it leaks more, shift shaft, drive shaft....etc..

It could be as simple as the drain/vent screw gaskets were not good or not tight.........that would allow water intrusion.