89 Yamaha Pro 50-Crankshaft noise or not Crankshaft noise

Fredontheriver

Recruit
Joined
Apr 14, 2010
Messages
2
This seems somewhat complicated.

I bought the referenced engine and had our local outboard repair person attend the initial startup.

It had not run in about a year. The carbs obviously needed some work but that is not my most urgent concern.

It started and ran fairly well, given the conditions stated.

I asked the the local expert what he thought and he said it sounds like the main rod bearings are getting ready to go. The question to him was--how do you figure that?

He said the engine was making a wooooooring sound maybe like a large fan or something like that. My ears don't seem to work in that frequency and the sound was not noticeable by me. It sounded like a typical running outboard motor with a miss here and there.

I can return the motor and get the money back. The dilemma is the motor is mounted on the party barge along with the control box, etc.

Question: Can failing main bearings be determined by listening to the motor run--the answer is, of course it can but this would depend on the degree of deterioration. If it is getting ready to come apart, there would obviously be noticeable noise.

I have confidence in out local guy but I really don't know what the next step should be. We checked the compression and got 120 on all three.

Would somebody offer some insite---please?
 

robert graham

Admiral
Joined
Apr 16, 2009
Messages
6,908
Re: 89 Yamaha Pro 50-Crankshaft noise or not Crankshaft noise

A 20+ year old 2 stroke outboard is probably going to make some whiring and clicking noises, my 1999 makes noises. It's really hard to say if your motor is near ready to self-destruct but if it's running good maybe you should just go ahead and enjoy it and don't worry about it. My wife and I were launching the boat several years ago and I thought I heard a noise in the motor, she said the noise was mostly in my head and that I was being paranoid, and you know what, she was right! Several years later, motor still running fine! Noises in head!
 

Doh

Petty Officer 2nd Class
Joined
Aug 12, 2008
Messages
187
Re: 89 Yamaha Pro 50-Crankshaft noise or not Crankshaft noise

I could tell if a Snowmobile engine needed crank bearings, by listening for a rolling sound after the engine was shut down. The plastic cage would melt, and the balls would continue to turn after you shut it down.

I could never tell if a rod bearing was on it's way out. But that was 2 cylinders. There are feq's to listen for (wish I am not sure of on a 3 cylinder Yamaha) but rod bearings? Needle Bearings, um I am a little sceptical. But not in disbelief. The needles are incased in plastic as well.

So the next question is "Are you basically stealing the motor at the price?" Is there a reason that he may want it?

3 cyl Yamaha's are basically Indestructable and highly saleable, If he knows the price is lower than he could resell it for, well that may be it.
 
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