Re: Big Twin Lower Unit Reseal Question

[raglover]

Thanks for the replies. Let me give some more detail.

I completely resealed, including shift o ring. Use scotch weld 847 new prop shat drive shaft and spaghetti seal. Standard fare for the split case. Resealed quite a few but this one is troubling me.

Testing first at 8 psi under water and rotating…..no bubbles.

It will hold pressure for hours. Using the Stevens instruments gear case pressure tester and a Miley vac vacuum tester…the latter it under water. Vac test fails faster but cannot tell where.

Shafts are good, no grooves….actually a later lower unit that had zero noticeable wear but had evidence of a prior reseal with too much 847.

Here is how the leak exhibits. Fresh oil passed all pressure tests. Run it for an hour on boat. Drain and it is milky….more so than just the air bubbles. Some times there was trace amount of oil behind prop. Tore it down and resealed with new prop shaft seal and spaghetti seal and required cleaning. Ran it again after passing all pressure testing and same result but this time no oil behind prop…..looks like there is more than just tcw3 oil in exhaust cavity when I drop lu. Even ran the motor on an old tempo hose tester and got no water in oil.

Only conclusion I have is a seal is failing under water under way. Because I pass pressure testing (best I can tell) I was thinking I had water getting sucked in….thus the theory on double stacking

Got me stumped and I want to get the boat going for a meet in Chaplin next week.

Thanks for all input and suggestions. Please keep them coming!

Allen