How do you test a lower unit for leaks.

[909]

How do you test a lower unit for leaks.

 

[Scott Danforth]

drain fluid

pressure test

 

[909]

Thanks Scott

 

[Chris1956]

If you have a gear oil pump, use the hose on a bicycle pump to add a few PSI to the gearcase and listen/watch for leaks.

if you don't have a gear oil pump, I recommend you get one. It makes adding gear oil much easier than squeezing the silly tubes.

 

[909]

Thanks for the idea Chris.

Don't have one yet (only a compression tester) , but will start looking.

I was thinking of using the air compressor in my trunk (for tires) and just spray down the lower unit with soapy water to watch for bubbles.

 

[Chris1956]

OK, but not too much pressure, or you will have a leak. Say 5psi max?

 

[Crosbyman]

danbar gearcase pressuretest - Google Search

 

[racerone]

Using a compressor is an absolute mistake.-----I use a bicycle pump.-----Gives you proper control of pressure!

 

[maineiac5586]

From what I've read testing should be done around 15 psi not 5 psi

 

[tphoyt]

I use a brake bleeder/ vacuum gauge and check with both pressure and vacuum. It is possible for a seal to leak in one direction and not the other. Im happy with 10 psi. And I agreed with Racer on the using a compressor. It only take a split second to blow the seal.

 

[Crosbyman]

I use a brake bleeder/ vacuum gauge and check with both pressure and vacuum. It is possible for a seal to leak in one direction and not the other. Im happy with 10 psi. And I agreed with Racer on the using a compressor. It only take a split second to blow the seal.

above suggested Danbar video pressure tester works great and not to expensive.

I tested both pressure and vacum on my 75 ETEC GC and small engines from 1950-60s trick is to find the GC fitting to fit the hose and GC

I used this one...comes with the proper adapters

General PDP Template

www.canadiantire.ca

 

[racerone]

Not hard to make an adapter.----Thread in many domestic gearcases is 3/8--NC ----Piece of 3/8- NC bolt with 1/8th hole.----Brass tee ( modified ? ) for a gauge and shreader valve.---Use JB weld to glue pieces into the brass tee.----Not hard to make something that will work. ----Made my own adapter 40 years ago.

 

[Scott Danforth]

I use my mityvac 8500. it can switch between pressure and vacuum.

Volvo gear boxes have a spec for both pressure and vacuum testing
I believe Merc only has a pressure spec

mityvac mv8500 - Google Search

the kit comes with adapters for most anything:

• pressure bleeding your brakes
• pressure testing a cooling system
• I use the adapter off the gear oil pump to pressure test the gear cases.