I currently have a Borg Warner trans with tailstock that is in front of a Merc 3A. Prior to pulling the engine for minor repairs, the transmission had a leak out the rear. When the fluid level would get low, the transmission would slip slightly while getting onto plane. I would add fluid to the full level and run without any problem until the fluid worked its way out the of back and was low. While the transmission was out, I replaced the seal in the back of the transmission where it was leaking from. I understand that people state once the fluid gets low and it slips once, its shot.... Given this had only happened a few times prior to replacing the rear seal, does anyone really see a problem arising? The boat is powered by a 540 C.I. Nat Asp engine.
Are there some type of ways to check the trans with the boat back together? Ex. Boat off with trans in forward gear and trying to turn prop? Or trans in neutral? Thank You.

I would have them checked while you have them in your hands!!! Might still be good but not for long... better open them now to see instead later when back in the boat imo!

No longer in my hands. Re installed in boat already. If its still good, I would imagine it would stay that way unless a different failure would arise. I imagine the constant loss of fluid is what triggered the slippage when getting onto plane. I agree when it was out was a good time to have it cracked open. Have other users had a loss of fluid in their trans cause slippage then go away after added?
Also when boat was running on trailer, the trans shifted into fwd/rev still very nicely....

The slippage isn't good for it, but it should be able to take a little without severe damage. Is the fluid burned and does the prop turn while its idling in neutral? Those are both signs of damaged and warped clutches.

If not, and its not slipping it may be fine.

Fluid never looked burnt. I have not checked to see if the prop shaft turns in neutral while idling. However, while it was idling and I put in fwd/rev from inside the boat, it did drop in rpm a little indicating it was now turning... Having not checked though, I feel that was a good indicator that while in neutral, it doesn't spin.
Your thought?
I will run the boat tomorrow to see if it spins too.

twinrig,

what kind of boat and how many inches below the bottom of the boat is your prop shaft ?
not related to your your problems, just sounds like a single engine boat and i'm curious about your set up is why i'm askinig
good luck getting it sorted out

Ran the boat today on the trailer. Purged the system of air at 2500 RPM and idled down to 1000 RPM as BAM suggest to check fluid. Added half a quart. With the boat idling at 1000 RPM, the prop shaft was turning Sloooooooooooow. Nothing how its like when actually engaged. With that said and all that ive been reading, I feel like everything is fine.

The boat is a 26 Larry Smith Scarab. Prop shaft is deep... I'd say around 6 inches. That's just how they were back in the day i guess.......

wow, awesome boat
thanks for the info, hope she's good to go