Testing a lower unit

[ddbyrd3]

I just replaced my Prop housing seals and bearings.<br /><br />Before I add oil, and take it out for a test run I would like to do a test on it to see if it holds pressure and or vacuum.<br /><br />What range (psi) should I use and for how long if I perform a vacuum test?????<br /><br />It is a 140hp Johnny j140txcim

 

[Cricket Too]

Re: Testing a lower unit

I'm not sure about vacuum, but if you want to pressure test it I think around 10 or 12 psi should hold in there, I wouldn't put anymore than 12 psi.

 

[ddbyrd3]

Re: Testing a lower unit

I believe you can do either or..... I just dont know the details of either, plus I have a vacuum pump.......

 

[Paul Moir]

Re: Testing a lower unit

Yes, you're correct. Testing both is a more thorough test. Use 15" of vaccum for your test. I guess that's around -7psi.

 

[ddbyrd3]

Re: Testing a lower unit

Thanks Paul, how long should I allow it to hold vacuum for??????

 

[Lasse Lehtonen]

Re: Testing a lower unit

I have never done this test and I dont know for how long it should take -7 psi vacum but I know that you can test that nothing is leaking by putting a -7 psi vacum in it and putting it in a water tank for a while and when you are finished your test, check at there is no water inside your lower unit.This test should tell the truth cause lower unit seals are made to hold water out of your lower unit.