Lower unit air test?

[foulpole18]

I found that my 89 johnson 25 hp motor looks to have a small leak in the lower unit. This has happened before and I have had it air tested. Which it passed all 3 times. It only seems to happen when it get really cold or warm in my garage. Could this just be seals expanding and contracting? I was wondering how a guy would go about doing an air test for yourself. Drain the lower unit oil and hook up a valve and gauge to it and pump up with a compressor I would think. What kind of psi do they test at?

Thank in advance

Brian

[boatfixer]

They only need about 12-15 lbs and NO more. You are going to need a small pump, low presure guage and correct fittings. On my set up, I even have a shut off between the pump and guage. Are you sure its gear lube and not unburned oil from the exhaust?

[foulpole18]

No Im not positive. I was kind of wondering if thats it because it has passed 3 air test in the last 8 years. It doesnt really stink like gear lube either. Should I use it a few times and then check/change the gear lube and look for signs of water?

[boatfixer]

If its real stinky and black, its more than likely from the exhaust. Keep an eye on it.

[foulpole18]

Ok I will. Thanks for the help

Brian