pressure/vacumn testing gearcase?

[james yarosz]

I have a 1976 85 hp johnson that keeps leaking water into the gearcase. Rather than guessing where it is leaking I would like to pressure or vacumn test the gearcase.Can anyone tell how this is done. I have an air compressor,regulators,and a vacumn pump.

 

[oldcatamount]

Re: pressure/vacumn testing gearcase?

Drain the gear oil out of the lower unit (actually, you could do it with the oil in it). You'll need to rig an adaptor that will screw into either the upper or lower drain/re-fill screw hole and then to your air hose. If your motor is on the boat, you'll need to put a barrel under the motor with enough water to cover the gearcase. Don't put more than 8 - 10 pounds of air into the gearcase. Watch for bubbles.

 

[james yarosz]

Re: pressure/vacumn testing gearcase?

Thank,s for the reply.The gearcase is on the motor but I'll probally pull it of to test it since it will have to come off to repair anyways.Thank's again. Jim

 

[DC20]

Re: pressure/vacumn testing gearcase?

If you have a hot tub, it works great for submursing the unit into. Just don't let the Admiral see you do it.

 

[james yarosz]

Re: pressure/vacumn testing gearcase?

Did the pressure test and had bubbles coming from the back of the bearing housing.Pulled it out and the large O ring was split. Replaced the O ring and no more bubbles.I put the gear case back on the outboard and ran the motor on the ear muffs in the driveway for about 15 minutes.Not getting much water out of the exhaust but water is squirting out between the gear case and the exhaust housing.Is this right.The water must be circulating through the motor because after 15 minutes the heads were barely warm.Any ideas?

 

[boobie]

Re: pressure/vacumn testing gearcase?

Whenever you pressure and vacuum test a G/C the oil should be out of it as it can act as a seal and may give you false readings.