if it's a merc there is a key that holds the gear for the pump. The gear likes to break right at the key. But, When mine broke, I didn't have forward or reverse. I had no pump pressure at all. I don't see how it could break so that you have pump pressure at idle.

The trans is pretty simple. but you have to pull your drive, engine and trans to get at the trans.

I still had reverse

The clutch plates probably deteriorated.

If you had any water in there they go away fast!

I drained some of the oil from the out drive nothing it looked great no particles or water in it the transmission oil also looked great both smelled like clean oil no burnt smell the transmission will go into gear both forward and reverse on trailer no sounds coming from out drive or transmission i don't know what oil is in there because I only recently bought it if i need to replace it is there a stronger transmission i can put in there i have a motor being built now for it it will have around 550 hp and what do the run in price

No they were ok. Easy to spot as oil froths out the oil vent

When everything is cold i do have forward and reverse after about 10 minuets of running in gear it quits just like it went to neutral this is on trailer thanks

Clutch pack done for! Call Tom Huber, Huber Marine Transmissions, Inc. 615-794-7583. He can make your MerCtrans II good for over 500 H.P. Otherwise you will HAVE to go to a B-W unit and that will take up 5.5 or 6.5 more inches length depending on whether you use a 71C or 72C unit. Marc Berman at BAM Marine is also a great source of knowledge on this stuff. Just got done researching all this myself and those two guys can answer all your questions and save you lots of floundering around. Later! --- Jer

What he said.

THANKS EVERYONE I thank god for forums like these that can give some one a helping hand that has know idea of whats going on before this boat i had a 21 ft jet

let us know what the problem was, when it becomes clear