Prop or Engine issue? 2.3L OMC 18' BR. At one point engines RPMS seem to spiral.

[sph130]

As I was just poking around the net I read forums about engines overrevving because of inproper pitch on a prop.

So heres my story. Bought an older 88' bayliner with a 2.3L OMC I/O. After a month it hiccupped and died. Brought it to the shop. Had major tune-up and a timing issue corrected because of a broken Dist. roll pin.

Anyway boat came back. Fixed. Runs like a champ or so I think.

I am out on the water going close to full throttle. I adjust the trim a little to bring the bow out of the water. I am going fast for that boat 41mph. Then all of the sudden my RPMS beging to increase rapidly. I need to bring the throttle back to stop it from increasing out of control.

It was almost like I had the prop out of the water or there was no resisitance.

My Question: Is this because of a bad pitch on the prop - or some other known reason because of my trim that I shouldn't do?

Thanks,
Sean

 

[steelespike]

Re: Prop or Engine issue? 2.3L OMC 18' BR. At one point engines RPMS seem to spiral.

Your prop was probably ventilating.you may have picked up some junk/weeds on the prop Usually if you slow down and use reverse it will throw of the weeds.Look on the prop for the size.May be on the barrel or under the prop nut.Is the prop in excellent shape?Another possibility is the engine coupler.Not even sure where it is but it can cause a slipping affect.
A spun hub on the prop usually just plain revs and the boat losses speed drastically.Doesn't go away.Boat would usually not be able to plane without over reving.