Gearcase Tips

SERVICE TIP Are you suspicious that your gearcase is leaking because you see black oil "leaking" around the propeller or collecting on the garage floor under the lower unit? Relax, because 9 times out of 10 what your seeing is simply the residual lubricating oil running down out of the exhaust housing. When the motor is running, the unburned oil (95% of it) gets mixed with the cooling water discharged into the midsection's exhaust tube. Here it collects as an foamy emulsion, especially if the motor was used for extended period at low speed. After you put it up, the water evaporates, leaving the oil to run down and out the weep holes and the exhaust hub.

Best check first that the oil IN the gear housing is O.K., simply crack the lower screw and let a little out. It should be light to medium brown in color, and at least translucent.. Lighter, opaque and creamy colored indicates water intrusion. Inky black & burnt odor - - it's past due for a change. 100 % water, Bubbly grey-black gleep, under pressure, metallic colors, bad odors indicate serious problems. Unsure? Contact the Mastertech! At any rate, change the oil every 50 running hours using a high quality lube such as OMC's Ultra HPF and you shouldn't have any problems.

Operating in fishing waters? Good idea to remove the propeller occasionally and check for monofilament fishline around the propshaft. It'll cut the seals right out and - blooie!

Cooling system and waterpump ills can be alleviated by replacing the pump every so often. Impellers take a set when unused and can shed vanes fast when you operate the outboard after an extended period of storage. I advise that ANY motor which has been idle for more than 1 year have a VISUAL check of the pump. It's real easy to install a new impeller and avoid extensive engine damage caused by an overheat.

Waterpump telltale quit? Check it by blowing air back thru to disloge a small piece of residue blocking the passage. The thermostat should also be checked and replaced every so often, especially in saltwater areas.