Prop is making a clunking noise

I have a 1988 Four Winns 170 Freedom. OMC Cobra 4 Cyl. 3 L. I bought a new prop. Put that on yesterday and also just started up the boat for the first time this year. When i started it the prop started making a clunking noise and it will move back and forth a litlle.

 

This should probably be in the Stern Drive section. If the play is between the prop and the prop shaft then you probably need a new key or clutch. If the play is in the drive train, then check all the u joints. Is the lower unit is filled with oil?

 

Did you install the spacer?

 

Yes i did. and i tried it without the spacer and it got worse. Do you think i might need a second spacer. Or could it just be the prop. My old one never made that sound before. But i dont want to use it cause it is tore up. Gona try today taking off the prop and starting the engine. Had to wait for the battery to recharge it died on me to.