Grinding Noise w/ SS prop

[Grinding Noise]

I have a 2000 Ranger w/ 90HP Mercury engine. My aluminum prop was bent so I decided to go with a SS prop using the same pitch 12 x 3/4 x 21P. In doing so, I notice a grinding noise at low speeds(trolling). I was told by a Mercury dealer, " The 3 cylinder 90HP was not designed to hold the SS prop. The weight of the SS prop effects the light flywheel of the engine, creating this grinding noise." I also noticed my hole shot was not as good. The top speed increased a few mph. Has anyone else experienced this problem.

 

[Chris1956]

Re: Grinding Noise w/ SS prop

I guess I have a dumb question. Did you ensure the thrust hub was behind the propeller when you changed it? Without the thrust hub the prop rubbs against the gear housing.

 

[Kenny Bush]

Re: Grinding Noise w/ SS prop

I agree as posted by Chris, that your thrust hub(big washer in front of prop) may be wrong. I have never heard of a grinding noise due to "Composition of Prop". I do agree that a stainless prop is heavier, and if the flywheel is light, it may bog a little putting in gear and idling around. But Grinding due to stainless? Anyone out there heard of this?

 

[DHPMARINE]

Re: Grinding Noise w/ SS prop

There is a service bulletin that refers to a clattering or growling noise when idling in gear.It covers 60HP thru 250HP outboards using SS props,but does not occur in all boat/motor combinations.The cure is to go back to aluminum,and is not a warranty situation.<br />Try putting an aluminum prop back on.If the "noise" stops,probably this is it.\<br />DHP

 

[quantumleap]

Re: Grinding Noise w/ SS prop

My 97 125 makes more noise and vibration with the stainless prop on especially at idle. The instructions that came with the prop state that on some motors, increased vibration may occur. To me, vibration equates with wear on gear components and the grinding noise you are describing would definately persuade me to go back to aluminum. I did, although I really wanted the durability and looks of stainless. I have heard few people with the midsize merc 3 & 4 cylinder motors complain of problems with stainless props. I feel that some cause more problems than others. By the way my ss is a Ballistic. Good luck.

 

[Grinding Noise]

Re: Grinding Noise w/ SS prop

Thanks for all of the replys. This is the first time i have used this kind of forum. I do have the thrust washer in place. I also removed the SS prop and tried the old aluminum prop and the noise went away. Unless I find out something different... I will stick with the aluminum prop. FYI, my SS prop was made by Stelletto.

 

[Grinding Noise]

Re: Grinding Noise w/ SS prop

DHP, you mentioned a service bulletin for these motors. Where could I find this kind of information. I checked with Mercury and they would not let me speek to Tech Services. Customer service said they would talk to Tech services and get back to me.<br /><br />Thanks

 

[DHPMARINE]

Re: Grinding Noise w/ SS prop

Yeh it is tough to get thru customer service,but that is so Merc mechanics can get thru.Even then it's hard,sometimes 15-30 minutes wait.<br />Someone out there may have a source for you to get the bulletins,but I don't.<br />I just pass on what I can.<br />DHP

 

[sjsmith]

Re: Grinding Noise w/ SS prop

i also changed to a s.s. prop on my 90h.p. merc. & experienced this chatter. i went back to my alum. &have no noise.i'm wondering, is there any lower unit modifications or kit that can be installed to utilize the s.s. prop?

 

[Texasmark]

Re: Grinding Noise w/ SS prop

Read the archives guys. I have been chasing this for a year and there is a lot of chatter about it.

Subject is " Clutch Dog Rattle" and according to Merc (service bulletin per my local Merc mechanic) it hurts nothing....just very annoying noises at idle. The rougher the engine runs the worse it is and conversely.

It is caused by the shifter clutch dog being spring loaded, the heavy (high pitched prop in my case) SS prop is screwing through the water (nice and smoothly) while the engine is going putt putt. So one set of gears is vibrating (rotating with intermittent power pulses) while the other is running smoothly. The spring allows the shifter dog to jump back and forth on the F gear.

Remember the gears are heat treated to a very high hardness and the whole thing is submerged in oil. Just give her a little throttle and it will go away........but it does make for a little shifting while trying to drive on to your trailer or docking if you choose not to listen to it.

HTH

Mark

 

[gss036]

Re: Grinding Noise w/ SS prop

When changed over to a SS prop on my 200 Merc, the only thing I noticed was a completely different "TONE" of the engine exhaust. Just took a few trips to get used to a different sound.

 

[Texasmark]

Re: Grinding Noise w/ SS prop

If 200 Merc means 200 hp then you won't see /hear the problem, beints it's a 6 cyl. Only when you have few cylinders hitting at a slow rate will you have it.

Mark