Noise when pulling a tube.

[ponchoman]

'93 4.3 Alpha gen2 drive. Went thru the wringer last year at the shop and did gimbal, ujoints, stub shaft ,prop shaft carrier etc. My boat still has what sounds like a bad bearing but it's only really noticable when added load is put on it. ie- tubing. Pulling and turning with a tube is the most noticable. Sounds like a grinding/vibration. Coupler appears ok so far. You feel it in the floor of the boat.

 

[ponchoman]

Prop is a 21 pitch. Maybe too much stress for it? 19 pitch better?

 

[tpenfield]

Maybe you could put a mechanic's stethoscope on various parts of the outdrive to try to isolate the noise, if it is a bad bearing.

You could turn the outdrive to see if the noise appears or is different. Probably best to do this in neutral or remove the prop first.

Of course vibration/noise while under load while turning typically points to u-joints or gimbal bearing, but those are recently replaced . . .

 

[QC]

"Vibration" and lower pitch ("grinding" not "whining") seems to point to U-Joints. Where is trim set for tubing? Trim full down (in) is similar to full up (out) as far as U-Joints are concerned. Turning is similar too; if angle deviated from straight is the same, stress (noise) is the same

Same U-Joints are good for 300 hp and taller gear ratio so I don't believe prop pitch should be an issue as far as load is concerned unless something is wrong.

 

[ponchoman]

The noise is faintly constant but its really quiet when the boat is still cold. Once you get warm and under way its louder. When thbing Md the tube slows the boat down around a turn, its at its loudest. I'm think a bearing in the out drive? They did the stub shaft but not its bearing from what I can see. I did have water in there over the winter last year.

 

[ponchoman]

Dble post

 

[ponchoman]

Would upper driveshaft bearings make this noise? There's a history of water intrusion.

 

[ponchoman]

Dble post