stainless prop causing lower unit noise

[Redwood1974]

I have a 2000 nitro with a mercury 90 hp 2-stroke it came with a aluminum prop and I purchased a stainless mercury prop to help pull out of the hole and a little more speed.It made a very big improvement all the way around. The problem I am having is at a slow idle there is a rattling noise in the lower unit and if you bump the throttle up it stops. Any suggestions?

 

[reddogg]

Re: stainless prop causing lower unit noise

Does the prop fit well? Is it nicking the vent plate? Is there excesive play in it (back to front)? Does your gear box have enough lube in it? Is the prop damaged (bent/warped blades)? When you installed it, did you use both washers (one behind the prop and one in front under the prop nut)? Just brainstormin.

red

 

[Redwood1974]

Re: stainless prop causing lower unit noise

The prop was new, it has about 3/16 play in and out

 

[Frank Acampora]

Re: stainless prop causing lower unit noise

Go over to the merc forum. I seem to remember reading there that some Mercs have a rattle in the lower unit due to drive dogs--it doesn't cause problems, just annoying. The heavier stainless prop may have started this with your engine.

 

[ufm82]

Re: stainless prop causing lower unit noise

Yep- it's the prop itself that causes it. The extra weight coupled with the inconsistent power pulse causes the noise. (He said it was a 2-stroke.) Very common and annoying but not a big deal IF it is just the typical rattling noise. My 150 hp does it too. Nothing to fear. I only hear it when I listen for it now and usually that's when I'm idling through a 7,000 mile long no-wake zone. LOL

UFM82

 

[3dees]

Re: stainless prop causing lower unit noise

does the prop have the Flo Torq II hub by chance. these are known to rattle. if so it won't hurt anything, but changing to the Flo Torq III will stop the noise.

 

[retiredfornow]

Re: stainless prop causing lower unit noise

Yep- it's the prop itself that causes it. The extra weight coupled with the inconsistent power pulse causes the noise. (He said it was a 2-stroke.) Very common and annoying but not a big deal IF it is just the typical rattling noise. My 150 hp does it too. Nothing to fear. I only hear it when I listen for it now and usually that's when I'm idling through a 7,000 mile long no-wake zone. LOL

UFM82

LOL, you have a 7,000 mile long no-wake zone too?