1Boatnut

1990 502 mostly stock,usually 5200 rpm's max. I was out on the 4th ,and as I started to accelerate ,I was able to acheive 6000 rpm's and still had 1/2 throttle left. Right before this happened,I did hear a noise like I hit something. I drove back to the launch at idle speed. I pulled the prop off,and found a piece of plastic behind the prop. Something from the river not the boat. I take the boat for another blast,and now it seemed normal,but I lost about 5mph on the gps.Now the rpm's seemed back in the range. WTF......any ideas??

TomR

What are you runing for a prop?? If you are running a Merc Mirage plus or bravo, sounds like you spun out the plastic hub.
The good news is it is replacable, probably not a bad idea to go to a solid hub with the 502.

1Boatnut

TomR.....thanks for the info,but I am already running a solid hub in a 23 Mirage..

blue thunder

Sounds like you straightened up a blade. Do you notice any vibration?

BT

1Boatnut

b t...the props fine. No vibration. I am starting to suspect either the coupler,or the clutch cones. Any thought's anyone. And ,how do I diagnoisis??I did talk to a friend who owns a Marina (shop),and his thoughts were the same as mine

TomR

How many hours are on the motor and the drive ? Sounds like a coupler to me, though it could be the clutch in the drive. Did you smell something burning when it happened?? The smell of burning rubber is a sign of a bad coupler.

blue thunder

From my experience couplers don't partly fail. It's all or nothing. If it could do that though you would notice it mostly trying to get on plane... not at wot.

BT