92 Evinrude 40hp lower unit water intrusion: Where to start?

xjfish

Cadet
Joined
Jun 10, 2013
Messages
13
I had a milky oil in the gear-case situation going on at the end of last season in MN. Its time for me to get this fixed. I have replaced the impeller and related seals a few years ago. All has been well with the lower unit until last year. I did change the gear oil and put some silicone on the fill and drain plugs as the seals were questionable there. Still leaking. I have an OMC lower seal kit in hand. I would still need to pick up a few other things for the job. Unknown hours and service history on the outboard. I suspect prop-shaft seal has possibly been damaged from fishing line, but not sure. I do not have any outboard specific tools for the job or a holding fixture.

Where do you suggest I start here? Should I definitely attempt a pressure test with the lower unit still on boat? (I don't have a pressure tester, but feel like i could rig something up)

Possibly just replace prop-shaft seals if found leaking, drain/fill plugs and give it a try?

Would you just bite the bullet and remove the lower unit, replace everything, and then pressure/vac test before install?

Appreciate any advice. :)
 

racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
38,412
Those lower units are not considered robust.------And only an 89 / 90 / 91 / 92 model year lower unit would be a direct swap out.------Take good care of it as failure of it will be frustrating and expensive.
 

xjfish

Cadet
Joined
Jun 10, 2013
Messages
13
Thanks for the replies, I'm taking your advice. I'm going to pull the lower unit off today. I'm going to attempt to mount said lower unit onto my "car" engine stand somehow. I'm just going to go ahead and replace all the seals and pressure test before going back together. If i can get this thing secured to a stand and move the boat back into "storage" I will have some time to round up parts/supplies as needed.
 

xjfish

Cadet
Joined
Jun 10, 2013
Messages
13
I took my time and replaced all bearings and seals. This was not rocket science just a little tricky driving seals in without factory drivers, feel pretty good about everything. Internals and roller bearings look very good. I skipped the 3M or 1000 sealant on the shift shaft nut (used auto thread sealant), otherwise went mostly by the book...

Do you guys always pressure or vac test? I have a mityvac, sufficient? I highly suspect it will hold pressure now, not broke in with everything greased...
 

jimmbo

Supreme Mariner
Joined
May 24, 2004
Messages
13,636
No self respecting shop would not test a resealed unit...There little hand pumps for that.
 

oldboat1

Fleet Admiral
Joined
Apr 3, 2002
Messages
9,612
Mityvac will work fine for vacuum test. For pressure I use a foot pump with a pressure gauge, and a needle used for beach balls and such. Use a piece of gasket to pump a few lbs of air into the empty gearcase through a vent or fill hole, l.u. removed from motor. Use a spray bottle with some liquid soap to identify any leaks.
 

dazk14

Ensign
Joined
Jul 22, 2008
Messages
966
Your mightyvac will work great for pressure and vacuum testing. Use the fitting from a gearcase pump filler kit, a plastic one is fine. connect the fitting to thee mityvac via a short hose. The clear hose that coms with the fill kit should be fine.
As was mentioned, those lowers were not robust and we've parted out quite a few with perfect powerheads.
 
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