Volvo 275 outdrive slipping

[cb950]

I just bought a 77 skipjack 20' open. i took it out for the first time the other day, and upon accelerating the outdrive appears to slip. I tried two different props that i got with the boat whose condition is unknown.

After reading some posts I've figured out that my shift mech. was stopping 1/8" at most short of all the way in gear, but I heard no grinding when driving the boat. is it safe to assume that this is probably not the cause since i didn't hear grinding but could accelerate (sort of)?

If put into gear, I can turn the prop only with short bursts of motion against the resistance, and it doesn't turn the engine, but with the top of the outdrive removed, I can see the intermediate (vertical) drive shaft turning with the motion. The bearing, and brass nut look brand new. and i don't feel/hear any grinding. As far as i can tell, there is no "clutch" or place for slippage to occour in the outdrive. I don't know what it looks like where the engine connects to the outdrives main driveshaft, does the previously mentioned test indicate a problem in this area?

My next step is to take out the boat with the prop, and shaft marked to see if the prop hub is spinning for sure. if it is not, is driveshaft stripped? any other ideas?
Thanks!

 

[Don S]

Re: Volvo 275 outdrive slipping

After reading some posts I've figured out that my shift mech. was stopping 1/8" at most short of all the way in gear, but I heard no grinding when driving the boat. is it safe to assume that this is probably not the cause since i didn't hear grinding but could accelerate (sort of)?

It's a cone clutch, you won't hear any grinding as the gears are always in contact with each other. If it's not going all the way into gear, it may be a cable problem to get it all the way into gear, or possibly an adjustment if going to far into reverse.
Being a cone clutch, if it slips enough time, it can damage the clutch cone and you would need to replace it. But I would get it shifting all the way into gear first before replacing the shift cone. They ARE spendy.
Also make sure there isn't any water in the gear lube (MILKY) that will make them slip big time.

The cone clutch is in the upper gear box, and no, you can't see the seating surfaces without taking the gear box apart. Without a manual or experience, I wouldn't suggest you take it apart.

Here is a link to the OEM manual. Better start reading.

http://www.4shared.com/account/file/48536730/fa3b3311/280_to_DP-C_Drive_manual.html

 

[cb950]

Re: Volvo 275 outdrive slipping

The oil was waterless. Thank you for that manual. I will first drive test the prop, and shift cable, and go from there.

 

[cb950]

Re: Volvo 275 outdrive slipping

Problem Solved! It was actually cavitation. I moved the trim bar down all the way to the far back hole, and it's fixed. I can't believe that the 2 or 3 degrees of trim screwed it up that bad.