2002 20i trans slipping? Help diagnose please.

[Tigety]

I am new to this forum but glad to find it. I just bought a 2002 20i with 406 hours on the clock. At about 425hrs I noticed that when deep water starting a skier it sounds like the trans might be slipping. I've never had this problem on my other direct drives before. When you hit it, the boat takes off, goes about 30 ft. then the engine revs way up for about 3 sec and then boat takes off and pulls fine. When the engine revs it sounds like the prop is cavitating so I don't know how to diagnose this properly. How does one know if in fact the trans is slipping. Will it slip at all speeds or only when torque demand is high?

Any thoughts or opinions are appreciated.

[SATige]

Sounds very familiar. I have a 2002 21v, had the same issue when I bought it. It turned out to be low on trani fluid, that's it! The owners manual from that year is wrong on the amount of fluid that you should be running which causes this to happen a lot. You can find plenty if information on this site regarding type and quantity of fluid.

[bolo]

Yep, most likely tranny fluid low. Search the archives on here as the l p suggests. Have had this issue with a 99 21i