mercruiser vibration

[naturecoast1]

My dad has a 1980 Grady White 22 ft, with a 238 mercruiser (305 v-8 with Alpha One outdrive). In excellent, well maintained condition.

Yesterday, I ran it aground on a soft sandbar. Stalled the engine at around 20mph.

There is no visable damage to anything. The grounding kicked the outdrive up and knocked the exhaust bellows loose or tore them. Either way, exhaust is now exiting through the relief ports. But, I heard the beginnings of that symptom prior to the grounding.

Boat starts, shifts and runs fine. But, there is a fairly good vibration above 2,000 rpm and very poor high end power.

Since this is my first experience with an I/O. I am wondering how siginificant would the vibration be from a bent aluminum prop? This is my first suspect for the damage.

Also, what other problems could result in silent smooth running at 1800 rpm but significant vibration above that, coupled with the loss of power.

Just trying to formulate a plan before I start disassembly.

Thanks, in advance, for any help.

 

[Bondo]

Re: mercruiser vibration

Welcome Aboard to the forums here at iboats,......

A Bent up Prop is a Good Possiblity,.......
It's also the Quickest,+ Easiest thing to Try........

If the outdrive is the Original drive,... It's a Pre-Alpha,... Not an Alpha 1.....
Not that it Really Matters,.... Til you try to buy Parts.....

 

[naturecoast1]

Re: mercruiser vibration

Welcome Aboard to the forums here at iboats,......

A Bent up Prop is a Good Possiblity,.......
It's also the Quickest,+ Easiest thing to Try........

If the outdrive is the Original drive,... It's a Pre-Alpha,... Not an Alpha 1.....
Not that it Really Matters,.... Til you try to buy Parts.....

 

[naturecoast1]

Re: mercruiser vibration

Thanks,

The outdrive was replaced with a reman alpha one unit. I think I will try replacing the prop and having a test drive before I tackle the bellows.

 

[Reel Poor]

Re: mercruiser vibration

While you have the prop off check for a bent propshaft. You can do this with a stationary pointer pointed at the end of the propshaft and rotating the shaft by hand noticing distance changes between the pointer and shaft.