Bringing 1957 7.5 Evinrude back to life, seemed fine, then a squeal

[StarAmerican16]

This motor has been sitting for an unknown length of time, supposedly a couple of years. I bought this motor from someone, and they said the reason it sat for a couple of years was the rope would not recoil. The motor turned over fine, and seemed to have compression.

So I bought the motor really cheap (basically was given to me).

Took the top off, and found the plastic "pawl" broken, and replaced that, and then the recoil worked fine. I did not know what a pawl was before this, but I figured that out.

Took the plugs out, put some oil in the cylinders, and waited a day. I set it on an engine stand, and put the bottom end in a barrel. I put new gas in the two line tank, mixed the oil, and pumped it up.

It took a little bit of turning, but she started, then we got it to idle nice, and let it run for about 15 minutes, in a real smooth idle, and pumping water really good. Seemed to throttle up and down and shift really well.

Put it on a 12 foot john boat today, and put it in a lake. It was hard to start, but finally started. Let it idle for a few minutes, looked to be pumping water good, so I put it in forward, and cruised at medium throttle for about 2 minutes, then suddenly a quick loud pitched squealing noise, and the motor quit. I felt the block, it did not feel warm at all.

Paddled back to shore, took the motor home, and put it back in the barrel. The motor still spins freely, and my friend started it up when I wasn't there, and he said it ran quiet for about 20 seconds, then squealed again, and quit.

Now it spins freely, but is making the squealing sound. Did we just kill this motor?

 

[Chinewalker]

Re: Bringing 1957 7.5 Evinrude back to life, seemed fine, then a squeal

I almost want to say it is the shock absorber in the gearcase expanding. I had a 5.5hp with the same lower unit that would run fine in neutral, but a few seconds after putting it into gear it would make a squealing sound and shut down. The shock absorber was broken and would expand once a load was put on the prop.

Outside of that, it may be a connecting rod going. What oil ratio are you running?

 

[StarAmerican16]

Re: Bringing 1957 7.5 Evinrude back to life, seemed fine, then a squeal

I was using a 20:1 ratio.

I brought three other old motors back to life in the last year, a 1973 65 HP Johnson that was used all last summer and so far this year on the Starcraft American, and two older Mercs (1977 150 HP and 1975 Merc 115 HP), and have had no problems until now.

This little motor is extremely clean, especially under the cover, and it seemed to run fine until a load was put on it.

I have not yet gone back to my shop to look at it again.

I think I may have killed it though. It squealed (the sound seemed to be coming from the recoil area right on top).

The crazy thing is, it ran smooth for about 20 seconds the next time, then did the same thing.

Thanks Scott. I chatted with you a bit last year when I got the 16 foot open bow Starcraft American. We tore out the floor, and put in new foam and stringers. Did everything except paint the outside.

That boat has been awesome for us. Really fun boat.