64' Merc 500-Overheated

[BoatMan95]

Hi,

I have an 1964 Merc 500 that overheated. It did not lock up but will hardly turn over now with the plugs in. I fogged the cylinders and that help a little, but will not really turn over with the plugs in.

Is the powerhead shot?

Does anyone know if an outfit that sells rebuilt powerheads?

Thanks,
Mike
Seattle

 

[Fuzzytbay]

Re: 64' Merc 500-Overheated

I'd try and look inside, at the cylinder walls. You can do this two ways.
The first would be looking down through the spark plug holes. Either just with an led light, and peeking in. A better view would be by taking off the exhaust cover plate. This way you can see both the piston, and cylinder walls.
I'd be looking for scoring, burnt/melted rings, or piston domes. Its best to try and find out the whys of the problem, before you jump into a rebuild, or trade out powerheads.

 

[BoatMan95]

Re: 64' Merc 500-Overheated

Thanks! Will take a look at with an LED Light as first attempt. The motor has been a good runner but has suffered from being outside before I got it, taking anything apart is tough... the bolt heads break and leave the stud...

Will check it out and post back.

Thanks again,
Mike

 

[BoatMan95]

Re: 64' Merc 500-Overheated

Hi Fuzzytbay,

Well, you really know your stuff! I did take off the exhaust cover plate and look at cylinders 1&2. The walls looked shinny and the rings looked good and clean.. no scoring or burn marks.

I next turned to the started we and broke it down and found one of the brushes was burned and fell apart. The inside of the starter motor was scored and pitted with rush and dirt. Looks like water has got in there over the years.

I am not sure I can get a new starter from SeaWay Marine-Seattle or not.

Appreciate the advise, I must admit, I was really not looking forward to taring the power head down.

Thanks again, will post a final message once I get the merc running again.

 

[Fuzzytbay]

Re: 64' Merc 500-Overheated

You might be able to rebuild the current starter. You will need to get brushes, turn down the armture, maybe make up a new plate for the brushes.
All total if you have a decent machine shop around, 30-40 bucks. The cost depends upon wether you will need new bushings too.

 

[BoatMan95]

Re: 64' Merc 500-Overheated

Hi Fuzzytbay,

Good news!

I was able to get the starter motor rebuilt for $120. I first went with a "new" one but the case did not have mountings for the solenoid. I put a new water impeller in since it had been a while replacing the old one. The motor fired right off and we ran it today for a couple of hours on the lake, runs solid.

I have some issues on my control unit and throttle and shifting... time for a new post.

Thanks again for your advise, I was about ready to give up on this old merc.

Mike-Seattle

 

[Fuzzytbay]

Re: 64' Merc 500-Overheated

Thanks for posting back, its nice to get the followup on a solution to a problem.