1959 50hp evinrude troubles

[skrewflanders]

I purchased this motor used, new plugs, rotor, changed oil in the lower, tuned. Runs great, taken it out four or five times, never had an issue. Ran up on plain, sounded and ran great. I took it up to a different lake last weekend and went to run her back in after trolling all day. She got up on plain after warming up, no problems. After about 5 minutes the prop stops turning and the engine is just running wide open, throttle down and kill the engine. Look everything over, seems ok. Started right back up and slowly worked it back up to full throttle. After about a minute it did the same thing except there was some white smoke near the exhaust. Throttled down again, shifted to neutral and just let it run, sounded fine and no apparent issues. Give it a little throttle and shift into forward gear, ran great the rest of the way in and never missed a beat. Got it home and changed the oil, looked great. Wondering why it would do this but I'm at a loss aside from damage to the gears, which I'm really hoping it isn't. Any ideas?

 

[larky]

Re: 1959 50hp evinrude troubles

ok, "could be" one of two issues. what was the condition of the the lake? weedy? were there large floating patches of seaweed? if so, then it's possible that some of that seaweed was stuck on your lower unit causing cavitation (air bubbles around the prop). less resistance on the prop equals higher rpm's. the next condition could be a spun prop hub. its a safety feature built into the prop in order to spare the lower unit gear case in the event of an underwater rock/debris collision. the way to trouble shoot that condition is to clearly mark the prop to driveshaft position. maybe scribe a mark on the prop that is inline with the cotter pin in the prop nut. good luck, and let us know how you make out

 

[F_R]

Re: 1959 50hp evinrude troubles

Classic symptoms of a spun hub. However, spun hubs usually stay spun and don't self heal. I suspect larky hit upon it. Cavitation.

Scribe a line on the plastic prop nut (or use the cotter pin) and another on the prop. Run the motor till suspected slippage occurs. Stop motor and look at the marks. If no longer aligned, the hub slipped.

 

[skrewflanders]

Re: 1959 50hp evinrude troubles

I'm taking her back up this weekend, I'll definitely give that a try. It wasn't very windy and there is a bit of moss on that lake but not usually where I was at. Thanks for the replies, I'll give it a shot.

 

[boobie]

Re: 1959 50hp evinrude troubles

Weeds and moss will get you. Been there. If it happens again lift up the lower unit and see what's on it.

 

[Chris1956]

Re: 1959 50hp evinrude troubles

You might locate a prop shop near the lake or source a spare prop, incase it turns out to be a spun prop. You do not want to be "high and dry" on labor Day.

 

[skrewflanders]

Re: 1959 50hp evinrude troubles

I'm thinking it might be a cavitation problem, from what I've read it pretty much fits the bill as to what's happening. At any rate I always have my 6hp trolling motor and if I have to troll back to the dock I wouldn't mind a little "forced fishing time."