1972 50HP Merc questions

[brother1000]

I have two questions about my engine.<br /><br />1) What is the average top speed for a 50hp merc? It sits on a 16ft aluminum bass boat. Fiberglass hull w/ two live wells. Just wondering if it is at its top performance. Also wondering if a prop would make a difference. The one I have now is a little chewed up.<br /><br />2) How do you change the oil on the engine? It looks like you have to take the lower unit off, but I cannot find a socket to fit in that little hole.<br /><br />Thanks.

 

[mellowyellow]

Re: 1972 50HP Merc questions

welcome aboard,<br />speed depends on hull weight/design. a prop can<br />certainly make a diff. should run btw. 5-5500rpms.<br />to service the lower unit, remove top screw on<br />right side of leg, then lower screw. after oil<br />has drained, you fill it from the bottom until<br />it comes out top hole, the put screw back in.<br />get a service manual (bottom of this page)<br />or local library. worth it's weight in gold!<br />good luck,<br />M.Y.

 

[The Marine Doctor]

Re: 1972 50HP Merc questions

If you are correct with the year of the engine expect a top speed of around 25-28 mph.<br /><br />As for the gearoil...there should be 2 dimesize flat head screws on the gearcase. Remove these screws to drain and refill the gearcase.<br /><br />Once the oil has drained out..refill from the bottom until oil comes out the top hole..this forces any air out that is in the gearcase and replaces it with the oil.<br /><br />TMD

 

[tmcalavy]

Re: 1972 50HP Merc questions

the doc is right...the vent plug is on the port side of the lower unit...the drain plug is down under, on the front nose of the lower unit on the port side..you have to crawl to get at it.