MASTERTECH DEMONSTRATES HOW TO TUNE UP AN OLDER SMALL MOTOR.

On this last page we will go through replacing the water pump impeller and test running the completed motor.

Complete procedure continuing a major tune up on a small motor, in this case a 1962 Evinrude 3 HP. Just drop in here? GO TO PAGE 1 showing the initial setup and the magneto overhaul.

This particular model was built essentially unchanged from 1951 through 1967 and as a 4 HP up into the 90's. You couldn't ask for a better trolling motor. Where do YOU get one? E-bay and other auction sites have motors up for sale all the time. Yard sales, flea markets, even your local dealer may be happy to sell you an older motor they don't think is worth repairing. Use good judgment, don't buy a motor that is worn out! Generally the nicer looking ones are in good shape.

These are the components we are using to get this little jewel into perfect condition. All these parts will cost you just a little over $172.00. The entire project should only take you a Sunday afternoon, and will reward you with a motor that runs better than new.

Most of the small pictures are active links to full size photos to help you along. Just click to look, they will open in a new browser window. Feel free to print out any of this info FOR YOUR OWN USE ONLY!!

NEED MORE INFO?

SMALL CARBURETOR REFERENCE VIEW

3HP GEARCASE AND WATERPUMP REFERENCE VIEW

SHIFTING MODELS TYPICAL GEARCASE AND PUMP

GOT A DIFFERENT MOTOR?
TUNE KITS FOR OTHER OMC MOTORS
TUNE UP KITS 2 - 90 HP

The gearcase on this small motor is attached with only 4 bolts and should drop right off. I found even though this motor has little running time several problems in the water pump area. In the picture of the pump components on the bench, the small ring by the old impeller is some plastic melted through the plate and stuck to the drive shaft. You should NEVER run your motor out of the water as severe damage can occur to the pump in just seconds on larger motors. Here the damage was minimal and I replaced this plastic hubbed impeller with a brass hubbed one from my stock. This was also missing the small rubber O ring that is used at the top to seal the splined area where the shaft fits into the crank. Without this it would get rusty and soon wear out.

Clean the area where the stainless base plate is situated on the gearcase thoroughly to remove any old sealer, corrosion, or debris in the water intake area. Chase the threads where the housing attaches with a tap to clean out any corrosion. Examine the inside of the housing for wear, these wear the most in the center around the driveshaft and will suck air here and run hot at idle. Lightly face off the housing to remove any burrs, even if you are installing a new one. Of course this is unnecessary if you are working with a larger motor and a plastic pump with a stainless liner. Be sure to apply some molybdenum grease to the spline above the O ring. Without this the spline will wear out rapidly. Avoid excess and don't put any on the flat top of the driveshaft.

This one came out pretty nice for a $127.00 motor. Price I paid for living in Paradise (Hawaii) at the time, added $84.00 more for air shipping, but it was so well packed it could have survived just about anything. Too bad all I have to run these in here is salt water. So this one will be added to my collection for the time being.

Hope this little dissertation on small motor tune-ups was helpful to you. The project took about 5 hours without the photos and so on, you can do it easily in the same time frame.

I was just given a 1965 75 Johnson Electramatic V4 by a friend who shipped in a boat from Idaho. It is a beauty, I'll do some pages on how to tune it down the road.

GO TO PAGE 1 if you missed anything along the way!

I HIGHLY RECOMMEND you obtain an OEM model-specific service manual to help you. We have most linked RIGHT HERE at Mastertech.