Slipping Prop Loud Noise

[VisionIsle]

I was running 3400 RPM on my Volvo 240A / 280. A loud overwhelming raspy, stripping sound occured. I immediately lowered the rpm to idle speed. Besides the fact that it scared the hell out of me I was able to limp home at about 1200 RPM's. The sound of slight grinding and slipping occurs at 1400.

I have read some posts and will try to etch my prop and see if it is slipping, this seems like the case due to the following tests performed. The only thing is the noise that was assosciated with the slipping, just seemed worse than a prop slip (Although I've never heard one before)

Tests:

1) With the boat tied off at dock I ran the engine in gear to 1600 RPM, could not get the noise or slipping to occur. Did not want to run any higher for obvious reasons.

2) Ran it in idle, turned port and starboard, nothing out of ordinary on the U-Joints. Ran it in gear, with the same results.

3) Pulled the Prop, (prop less that 1 year old) noticed the paint was gone in areas and eating of the aluminum already starting in these areas. Edges are fine

4) Ran the boat in gear without the prop up to 3400RPM, no nosie or slipping

I have been told that the prop could have too much pitch for the wieght of the boat. Running a 15 x 15 prop, pushing 8,000 lbs. This prop reaches its expected WOT of 4000.

I replaced the prop because I was only reaching 3600 RPM at WOT using a 15 x 17.

Could a prop slip make such an awful sound? or am I in need of hauling the boat to look at more serious issues. And what might they be?

Any suggestions or comments would be helpful.

Thanks in advance.

 

[wvit1001]

Re: Slipping Prop Loud Noise

Sounds like the coupler.

 

[VisionIsle]

Re: Slipping Prop Loud Noise

Wouldnt the Coupler make noise when running without the prop at the RPMs mentioned? And i did not notice any smell of burnt rubber.

 

[Don S]

Re: Slipping Prop Loud Noise

A Volvo 240A doesn't have a rubber coupler, they do have a flex plate with springs in it. If it was bad, there would be no rubber smell, and also it wouldn't move anymore.
But you do have a cone clutch.
Check your drive oil for water. A slipping cone can chatter and make a noise. And, it's not a good sign either.

 

[VisionIsle]

Re: Slipping Prop Loud Noise

Don,

Are there any tests I can perform to check the cone clutch while in the water? It will be a while before I can haul the boat. Do you have a link to a diagram of what this cone clutch looks like? Your thoughts on the Prop slipping?

Carden

 

[Don S]

Re: Slipping Prop Loud Noise

Nothing you can do in the water.
As far as the prop, mark it like mentioned before, or put a different one on and see what it does.
There just isn't any "Easy" or "Cheap" buttons on this stuff.

 

[billbayliner]

Re: Slipping Prop Loud Noise

Go to this link and choose your outdrive to get the drive diagrams....


http://www.volvopentastore.com/Driv..._id.366--view_id.343516--search_type.category

Hope this helps

Bill

 

[VisionIsle]

Re: Slipping Prop Loud Noise

For all your input, thank you. I marked the prop and went out last Thursday. Could not duplicate the horrible sound but did notice that WOT was only getting to about 3700 RPM. After docking I decided to pull the prop and sure enough my marks were no longer together. I will be bringing it back to the prop shop (its got less than 15 hours on it) to hopefully get a new one for free. A word of advice to anyone who has not heard a prop slipping. It can be a crazy loud, raspy, grinding sound. I may have hit something soft, who knows. Also, Im going to mark my new prop before I even put it on. I suggest to anyone who has purchased or is planning on getting a new prop to mark the hub. This will save time and effort if it does slip.

Thanks again,

Carden