Recent cavitation while going straight

[Bassman42]

I have a 97 evinrude 115. E115eleua. Recently I noticed that even going straight the boat manages to cavitate. At least that's how it sounds. Thought it could be a weight issue. But the only thing that's changed is I replaced the sacrificial anode, it looks like a small stone. Not the anti cav plate. The old one was rattling around and the head of the bolt broke so I replaced it thinking it would fix it. Evidently it didn't. Motor has been mounted the same spot since 1997. Not an issue til 2 weeks ago. Sounds like it's cavitation, but could it also be the spark plug wires? A guy had jammed a circuit tester needle in the boots a while back and initially that's when it started. But 2 weeks ago it got a lot worse. Any ideas? Really need help!!

 

[emdsapmgr]

Possible that the rubber hub in the prop is slipping when the engine gets to max torque rpm's. You can check it yourself. Pull the prop off. Mark the center hub with a black magic marker. Across from that mark, make a mark on the aluminum of the prop. Run the boat. Remove the prop and see if the two marks are still across from each other. If not, the hub is bad. Get another prop.

 

[Bassman42]

I'm going to do that this weekend and will let you know! I honestly hope that's it! It makes sense, plus this is the original prop from 1997!!

 

[oldboat1]

The anode might be causing ventilation (not sure from your post where it is attached). If the issue started with anode replacement, though, think I would pull it off and see if the problem goes away. (agree with endsapmgr too -- reasonable to think a poss. prop hub issue)

 

[Bassman42]

Yeah because the problem has consistently gotten worse. The last week or two it's gotten really bad. It didn't matter if I trimmed the motor down all the way or not it still acted like it was cavitating, I have to get a new shift lever bushing, apparently mines gone and the engine vibrates like hell when I take off, but then goes away. Also putting on new plug wires, shade tree mechan jammed a circuit tester into plug boots. And putting on new nipple drain since he broke that too and said blocking it off wouldn't do anything.. Lies!!! Gas pouring down the back of the transom. Might cost cheaper labor but not worth it if having to fix everything else!!