More on the 56 15Hp

[frankr]

Or Marine tex??

[bullie]

More weirdness. I had the wire wheel on the drill so I took the paint off around the leak with that. I didn’t see anything obvious. I noticed the gauge was reading "0" on my gauge so I pumped it back up to about 8 lbs and put some more soapy water on the leak. Nothing. I took it back out to the barrel and submerged the whole LU again. Not a bubble. I donno. There were bubbles so there must be a hole or crack, but it really is weird that the leak stopped.

[david-bartlett]

Yah,

Those issues don’t usually fix themselves.

[dan-in-tn]

I would run the pressure up a little higher to check for porosity. As high as 15 lbs? Just remember you aren’t checking the seals anymore. No oil in the gearcase, right?

Dan in TN

[jerry-ahrens]

I’ll bet you sealed it up with the wire wheel. Probably smeared some aluminum over the leak.

[bullie]

quote Dan in TN:

I would run the pressure up a little higher to check for porosity. As high as 15 lbs? Just remember you aren’t checking the seals anymore. No oil in the gearcase, right?

Dan in TN

Dan,
No oil. I was checking my work before reinstalling and refilling the LU when I discovered the leak.

I will do just that and let you know what happens.

[johnyrude200]

I pressurize all gearcases to 16-17PSI. There are leaks in seals or housings that won’t reveal themselves until you get to that point. If it drops 1-2lbs over the course of 5 mins but stays put, you are good.

I’ve seen a few gearcases where there are pin holes you can’t see. WD-40 works really well like soapy water and doesn’t require anything other than pressing a button on the canister rather than mixing up the soapy water solution. In my experience, the only seals that really get to be a headache are driveshaft seals because the gearcase housing can often times be brittle or compromised.

JB weld works well on minor pin holes, cracks are usually a show stopper depending on location (if for instance, at a seem, JB weld will hold up, but if on a smooth concave/convex surface it will not work long term without significant grinding/etching).

QUESTION FOR THE OMC PLANT RETIREES:

What PSI does a gearcase develop during normal operational use?

[dan-in-tn]

I don’t like to run pressure up on small motors when looking for seal leaks. Can actually cause them to seal? I test at about 5 lbs for seal leaks then higher for spaghetti seal leaks, etc. Might go as high as 15 lbs. The gearcase is either sealed or it’s not. I would rather find it than put it back on the motor (especially 5.5/7.5)!

On big motors it depends on what’s going on. Those high HP units get hot. Poor lubes don’t tolerate heat/pressure well. Might see as high as 30 lbs, but the gearcase won’t last there. If the gearcase is blown then you get to find out when you remove the plug. If I start to loosen a plug (usually top plug) & it farts on me I tighten it back up. She is done. Nothing to rebuild anyway when they blow. Case is warped & she is junk! One bath in metal & burnt gear lube is all you need to learn your lesson.

OMC/BRP units only. I understand Merc has a blow off system around their shift rod seal. Yamaha may have the same thing. The new G2 has a gearcase reservoir. Not sure how that works, but gives extra oil. Older models only had 33 ozs of fluid/lube. The life of those high performance gearcases is lube changes.

Dan in TN

[johnyrude200]

Good info dan and glad the common sense approach is OK to follow. I follow the same conclusions you mentioned; if the gearcase shoots oil out when I loosen a drain/oil level screw, it is likely OK.

If it’s water logged, has metal, or nothing of course, well…probably the thing has an issue. Although as we know there are exceptions.

[bullie]

I pumped it up to about 18lbs and didn’t get a bubble from anywhere. Very weird.

[Author]

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