Water in lower unit after 2 re-seals

[jgreen.8]

After a prop seal started leaking on my 74 Johnson 25 h.p., I completely resealed the lower unit. After holding pressure overnight, I assumed it was O.K. Upon running it in water for a day, it lost about 1 oz. of oil and got some water in the oil. I tore it down, had all the seal fits repaired, replaced the drive shaft bearing and shift rod. After passing pressure testing, it still loses oil and gets water in the oil. The prop shaft has only .005 side play. Any ideas?

 

[alcan]

Re: Water in lower unit after 2 re-seals

Hi Jgreen<br />It's hard to say whats up on this. If your loosing oil and gaining water, there is a leak some where. Now all we have to determine is where and how. A presure test alone is never good enough in my opinion. I would presure test and vac test. Test while rotating the shafts by hand. See if you can locate the area where this leak is happening. Once you figure this out we can make a plan to repair.

 

[Paul Moir]

Re: Water in lower unit after 2 re-seals

Just another idea (had it happen only once before) - the propshaft isn't bent is it?

 

[rodbolt]

Re: Water in lower unit after 2 re-seals

hello<br /> carefully inspect the seal surface area for grooves at the drive and prop shafts. any pitting will cause a leak when running. how much pressure are you testing with?

 

[BillP]

Re: Water in lower unit after 2 re-seals

Did you use a new washer on the fill and drain plugs?<br /><br />Another area to check...Older OMCs had chrome plating on the drive shaft for the seal under the wp. I don't know if 1974s did but they might. The chrome gets corroded and the seal won't seal right...been there and done it. I couldn't find a used drive shaft anywhere without bad chrome and took mine to a machine shop for repair. They turned and polished the shaft to make it work. No problems after that.

 

[jgreen.8]

Re: Water in lower unit after 2 re-seals

All the seal fits have been built up and returned to standard size and shafts checked for staightness. All gaskets and o-rings replaced. Leak-checked up to 16 psi and vacuum checked. Holds forever. Only thing I can figure is the .005 play in the prop shaft bearing is the problem, but that isn't much play. I've rotated the shaft etc. Before repairing the seal fits, this would show leakage, but not after repairing them.

 

[R.Johnson]

Re: Water in lower unit after 2 re-seals

.005 side to side play in the prop shaft would be plenty. What does the inside of the prop shaft bushing look like. One reason for the wear on seal, and bearing wear on the drive shaft is a sprung gear case. Tolerance for the case being out of parallel is .025. Take a look at the pinion bearing also, and see what it looks like. It does not take much to spring these cases out of tolerance. That hollow web between the cavitaion plate, and prop shaft housing is not very thick. I measured 5 used gearcases to replace the case on my son's 18 before I found one straight enough to use. Remember also that a pressure, and vacuam test, is a static test.

 

[jgreen.8]

Re: Water in lower unit after 2 re-seals

Thanks for all the suggestions from all of you. I will check the case and bearings and I'm going to replace the prop shaft bearings if no other problems are found with the case. I will let you know what happens. It may be a while before I get it fixed and try it again. Thanks R. Johnson for the case info. I had completely forgot about a sprung case possibility.

 

[marinemech]

Re: Water in lower unit after 2 re-seals

have you looked at prop if its out of balance could also contribute to a water leak

 

[jgreen.8]

Re: Water in lower unit after 2 re-seals

I haven't checked the prop, but I don't have any vibration and it looks O.K. I'll check further. Thanks for the idea. I checked the case for parallel and it is out about .012. It appears to be close enough. Thanks again.

 

[jgreen.8]

Re: Water in lower unit after 2 re-seals

I replaced the prop shaft bearing and even rebushed the housing where the pinion gear runs. Replaced all the seals and leak-checked with pressure and vacuum again, but after running it a day, it was still about 1/2 oz. low on lub, so I feel it was inconclusive. I changed the oil and will try again another day.

 

[jgreen.8]

Re: Water in lower unit after 2 re-seals

I have run the engine several times now and it seems to be O.K. The tighter bushings seem to have solved the problem. Thanks to everyone who offered their ideas.