Pressure testing lower unit

mankato

Cadet
Joined
Oct 15, 2006
Messages
18
After a costly lower unit failure on a supposed new OEM complete lower unit, I'm thinking it would be a good idea to regularly pressure test my new gearcase myself. Does anyone else pressure test theirs and do you use a commercial tool or did you make one yourself ? Looking for ideas.
 

ezeke

Supreme Mariner
Joined
Sep 19, 2003
Messages
12,532
Re: Pressure testing lower unit

If you buy a 55008 Lube Tube like the one shown here, you will find that the male fitting is perfect for your gearcase.

http://www.iboats.com/mall/index.cg...=800107502&list_time=1162768411&view_id=47669

When you are not using the assembly for oil, you can put the fitting on any pump with a pressure gauge and do a good pressure test.

If you test whenever you drain the gear lube, just pump the empty gearcase to 10 to12 PSI, and submerge it. Any leaks will be apparent.
 

freddyray21

Commander
Joined
Jun 10, 2006
Messages
2,460
Re: Pressure testing lower unit

I cheat and use an old bike pump with a guage on it.
 

mankato

Cadet
Joined
Oct 15, 2006
Messages
18
Re: Pressure testing lower unit

Excellent.... thanks for all the ideas. I'm going to call a Mityvac distributor tomorrow and I'll order that Lubrimatic lube tube as well.That sounds like exactly what I was looking for. Thanks guys!
 

JUSTINTIME

Captain
Joined
Sep 2, 2006
Messages
3,284
Re: Pressure testing lower unit

remember to check vac and pressure on top vent hole
check pressure on fill hole (bottom) unless u only have 1 hole on your lower unit

also submerge it in water and let it stay in there for at least 2 hrs

some lower units can not handle over 15psi, so check this in the manufactures service manual not the aftermarket ones
 

ledgefinder

Ensign
Joined
May 2, 2002
Messages
916
Re: Pressure testing lower unit

Don't run the pressure too high - you could blow perfectly good seals. I run it two ways, just a couple psi (let it sit for 15 minutes), then 8 psi (leave it overnight, then check it). It's true you ideally want to both pressure & vacuum test it, but I find a pressure test followed by a lake test, finds just about any leaks.

Secondly, if you know you have a leak, a pressure test with the lower unit dunked in a tank, is a great way to find where the leak is. If it's been leaking, you generally should tear the LU down anyway, to check the bearings & surfaces, but it' still helps to know where it's leaking.
 
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