Homemade Lower unit tester

doral1985

Petty Officer 2nd Class
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Jun 19, 2011
Messages
107
Re: Homemade Lower unit tester

I done my pressure test and found a leak, one my output shaft bearing carrier bolts with the rubber backing was blowing bubbles, now goin to do a vacuum test, so if you lose vacuum how can you tell where its leaking?
OMC stringer 800 outdrive
 

Don S

Honorary Moderator Emeritus
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Aug 31, 2004
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62,321
Re: Homemade Lower unit tester

On any drive or lower unit, you fix the pressure leaks first, or you can't find a vacuum leak.
 

doral1985

Petty Officer 2nd Class
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Jun 19, 2011
Messages
107
Re: Homemade Lower unit tester

Got he pressure leak solved holds 10 psi overnight, just wanted to try the vacuum test, if it leaks how can i tell where its leaking?
 

Don S

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Re: Homemade Lower unit tester

First you listen. You can usually hear them. If not put some heavy oil on all the possible leak points and see if it stops leaking
 

doral1985

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Jun 19, 2011
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107
Re: Homemade Lower unit tester

ahhhhhh ok sounds good, going now to hook it up Tks Don appreciate it.
 

viper1

Petty Officer 1st Class
Joined
May 13, 2002
Messages
283
Re: Homemade Lower unit tester

Ayuh,.... My Bad viper1,... yer Right, I'm not.....:facepalm:

My apology,...

Well just saying what I was told. Like I said I personally never read it.
 

Friscoboater

Captain
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Jul 3, 2009
Messages
3,095
Re: Homemade Lower unit tester

I too have been very confused about his. One place says to pressure test it, and another says not too.
 

Fisherball

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Mar 19, 2009
Messages
470
Re: Homemade Lower unit tester

If it has a pressure leak, gear lube leaks out, you'll see the lube level drop. If you are getting water in the lower unit it kinda has to be a vacuum leak, sucking water in. I think?
 

Don S

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Re: Homemade Lower unit tester

I too have been very confused about his. One place says to pressure test it, and another says not too.

What have you read that says not to pressure test, and why? That makes no sense. If you do repair work on your drive, pressure testing is how you tell if the repair worked or not. It also confirms you didn't make a mistake like leaving a seal out where you shouldn't have, or it got bumped out of place.
 

Friscoboater

Captain
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Jul 3, 2009
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Re: Homemade Lower unit tester

Carp, I said that wrong. I meant to say vacuum test. I know you are supposed to pressure test. The conflicting info is on vacuum testing. Sorry Don :D
 

viper1

Petty Officer 1st Class
Joined
May 13, 2002
Messages
283
I consider it a safety. I built this for around 15.00 and made from mostly brass should last forever. I normally replace impellers and check out drives every 3years. In between I can check for leaks. When I reassemble it will make me feel better knowing there is no leaks. If oil can leak out then water can surely leak in. Like previously mentioned. If I got no loss of pressure but still have water when I change gear lube yearly then ill vacuum check. Least that's the game plan.

Sent from my DROIDX using Tapatalk
 

ktbarrentine

Lieutenant
Joined
Dec 12, 2011
Messages
1,296
Re: Homemade Lower unit tester

Done both the vacuum test and the pressure test. I limit the vacuum test to about 5 In. Hg. and it held great. Pressure tested to 15#. Did both tests on each half and then again when bolted together. Maybe overkill, but makes me feel better and it is actually fun to do (as long as your not chasing leaks!)
 
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