volvo outdrive slips when warmed up

[champ]

....So anyway. A great weekend to be out and just came home for a shower and some knowledge.
!7' champion
351 Windsor
volvo 270 outdrive
14x23 left hand prop

Boat sounds great good hole shot and lots of rpms left in motor. Changed to a new prop this year because I was getting some slippage last year. This occurs after about 20 minutes of high speed cruising. Prop has made a good change but slipping is still there. Idling for a few minutes and it is good to go again.
Any suggestions?

[MOP]

What oil are you using in the drive? It also could be the cone is getting glazed, that requires lapping in or replacement if it is too worn.

Phil

[OFFSHORE GINGER]

Just curious and to tell you the truth ,i do not know much about Volvo outdrives but do you have a bellows on the drive that might be cracked or leaking which will cause water to seep into the gear lube , and cause the slippage ?

[champ]

oil was a little low in outdrive, and added some 30w and it was clean with no signs of water. Was hoping it was the problem, but still slipping. I am thinking cone too after reading some other posts. Is this an easy fix ?