Water in OMC lower unit

[mcpark1]

Hi,<br /> I’m new to this forum but have an old problem that I have been unable to resolve. I’m hoping that someone on this forum can help. The problem is that I am getting water into my lower unit. I have a 1972 OMC 215hp (305 cid) electric shift out drive (Chevy small block 8 cylinder). So far I have replaced the prop shaft seals and o-rings on the gear head and applied redi sleeves to the prop shaft where the seals had worn groves. A couple of years ago I had to have one of the drive springs replaced, so they replaced all the other seals then. I’ve checked the prop shaft runout in several places and it ranged from 0.001” to 0.0015”. The drive will hold -25psi vacuum till the cows come home (I quit after 1 hour) out of the water (this is why I checked the runout). Same with pressure check. The last time I pulled the gear head; there was clearly water between the two seals for the prop shaft. I’m at a loss as to what to try next. Could there be a hair line fracture in the gear head? Should I replace that? I’m at the end of my rope, I’ve worked very hard to resurrect this boat from the dead and I’d really hate to chunk it all because of this one taunting leak. <br /> <br />Thanks in advance<br /><br />A chronicle of my work can be seen at Mark's Boat Restoration Project

 

[tommays]

Re: Water in OMC lower unit

your trying vacume what about pressure it should hold about 15 pounds<br /><br />also rotate the shafts while your testing sometimes they will only leak in one position<br /><br />once you find it you can fix it <br /><br />tommays

 

[KaGee]

Re: Water in OMC lower unit

Hi Mark,<br /><br />Welcome to Iboats! I saw your post on SternDrive. I wonder if you should just try the old fashioned dunk test in a barrell of water and watch for the bubbles. By "gearhead", do you mean the bearing carrier?

 

[mcpark1]

Re: Water in OMC lower unit

By gearhead I mean the "gear head assembly" OMC part #381849. It screws onto the lower unit and the prop shaft comes through it. It contains two seals and one needle bearing.<br /><br />I've tried a pressure test and it holds for more that 15 mins. I've tried turning the prop, but will try turning it slower. I've also thought about dropping the oil level just below the fill line, so I can apply the vacuum pump/gauge without getting oil in it and then hooking up the hose and starting the engine to see if it starts leaking. If not, I'll put it in gear and see if it leaks.<br /><br />Keith, my aunt lives in Toledo and teaches at Univ. of Toledo.

 

[tommays]

Re: Water in OMC lower unit

I've also thought about dropping the oil level just below the fill line, so I can apply the vacuum pump/gauge without getting oil in it and then hooking up the hose and starting the engine to

you are supposed to test for leaks with the oil drained that may be why its passing<br /><br /><br />tommays

 

[mcpark1]

Re: Water in OMC lower unit

I was only thinking of testing with oil in. All my other tests were with the oil drained.

 

[mcpark1]

Re: Water in OMC lower unit

Ok, here’s the latest. When I checked with oil in, it held a vacuum of -25psi. It continued to hold after starting the engine. It began to lose the vacuum when I put it in gear. Now, here’s the strange part… I continued to lose the vacuum after I shut the engine off. What would start leaking when the prop starts turning and continue leaking after the prop stopped. I’ve not determined how long it has to sit before the leak stops.<br />Seems to me it should have something to do with the seals around the prop shaft in the gearcase head assembly, but I just had those replaced. Any ideas?

 

[KaGee]

Re: Water in OMC lower unit

Wish I could help you Mark, not familiar with the old electric shift. Maybe Boomyal has a better idea.