Water in Stringer upper case after rebuild

So, I decided to do a bit of maintenance on my manual shift Stringer drive before heading to Lake Powell and have had quite the experience.

I have twin Stringer drives on my boat and knew the impellers had not been changed since 1987, so I had this crazy idea to go ahead and replace the transom boots and impellers in the drives before heading to Lake Powell this year. Well needless to say I should be on Lake Powell this very minute and I stuck home trying to figure out why I am not able to get one of the upper gear case sealed up so water does not enter and mix with the oil. I am not proud to say it but I have pulled that drive off 7 times now and it is getting a bit old and frustrating, I have definitely increased my removal time down to about 20 minutes. lol

Anyways, I am hoping a Stringer expert will chime in and help me out so I can get to the lake this year.

1. I have a Seloc manual and maybe that is my first problem, is there a better manual out there for rebuilding the upper gearcase?

2. For the life of me I can not figure out how water is entering the upper housing with only 5 to 10 min. of run time on muffs when I can pressurize the upper to 15 psi and have no leaks when submerged in water.

3. I follow the manual step by step and I have replaced all seals and it is still leaking. Is there a magic glue or permatex that I am not aware of? I have tried permatex aviation gasket, permatex #2, and gasket sealant and nothing has worked so far. It is not that complicated and I had no issues with my other drive that I replaced the impeller in.

4. When I run the boat on muffs alone doesn't that eliminate half the seals? Where should I be focusing my attention... I have ended up replacing all seals and o-rings throughout the upper trying to find the leak.

5. I am using permatex #2 (non-hardening) on both sides of the impeller plate 1/4 inch down, plus the impeller housing, and the bolts like the manual describes. I must simply be doing something wrong.

Thank you up front to anyone that might point me in the right direction.

Re: Water in Stringer upper case after rebuild

There have been a few of these uppers on these forums over the years. Best guess is some sort of hairline crack or corroded area between the water jacketing and the gear oil compartment. As you know the water is pumped through the casing to cool it and then to the mounting trunnions to get to the water directors. So water is in a cast-in jacket all around the gearbox.

Has the boat ever been through a winter with freezing temps?

Re: Water in Stringer upper case after rebuild

Yes, it definitely gets cold where I live, but I have never had this issue in the past and I left the boat in my heated shop all last winter.

I was also thinking a crack in the case but wouldn't I be able to see air leaking through it on a pressure test? I actually held the upper gear case upside down with the upper cover plate on and submerged it in in a water tank and applied 15 plus psi to the upper while under water with no leaks.

I am not sure a hair line crack would let the amount of water I am finding mixed in the gear case after only 5 to 10 min running on muffs. I am not kidding when I check the oil after running for a few minutes it is milky white and pressurized to the point that the oil shoots out of the case.

Thanks for your suggestion I will look very closely at the case when I pull it off again tomorrow.

Re: Water in Stringer upper case after rebuild

bcherrington, see your PM.