Need help diagnosing this one. I am running BW 10-17 trannys behind 8.1 HOs. after replacing forward clutches with graphite, new seals and rings, the port trans goes away, 3 times now. I was wondering what kind of pressure I should be getting out of the pump, and where do you tap for that test and what rpm ect. Thanks.

Check your dip stick length in trans. may be to long and you are running on low oil. I had similar problem with trans. stick was cause. Good luck

Thanks but the level is good, I am thinking it may be in the relief valve but I dont have any specs to go buy, any knowledge in this area would be greatly appreciated,

what kind of oil are you running??? Regular ATF isn't good, you should be using Type-F trans fluid with those clutch plates.

type f fluid and also using Huber forward clutch apply pistons

If you don't hear anything here, try these guys... they're very helpful too.

http://www.marinegears.com/techboard/

Ok so I ran the engines on the hose and did transmission pressure tests. idle 130 psi, 1500 rpm 160 psi, also pulled the control valve and dissasembled the pressure relief valve and found it to be free and in good condition, the trans that is not slipping has the same pressures, please help me before I go crazzy and buy a jet ski.

Now don't go off the deep end and buy a jet ski!

What drives are you running and do you have nose cones? Had a minor chip in nose cone filler and at speeds at about 75 mph. started to act as if trans. was slipping. Would never have guessed such a minor defect would have caused such a prob. Pulled trans. and found no prob. I can understand your frustation.

yes nose cones on trs, but no prop slip, had that before and can recognize that, and on every tear down forward clutches are burned.