1991 Mercury 150hp: Not cranked in 5 years - What should I do before starting it

[kuykendall]

I have a 1991 150hp Mercury XR4 that has been setting up outside (covered)and not cranked in approximately 5 years. What precautions should I take before I attempt to start the engine to prevent engine damage? Friends (non-mechanics)have recommended that I remove the spark plugs and pour oil into the cylinders and let it sit for a few weeks before attempting to start the engine. Should I do this or not? If so, what other things should I do?

 

[Fouled Plug]

Re: 1991 Mercury 150hp: Not cranked in 5 years - What should I do before startin

Re: 1991 Mercury 150hp: Not cranked in 5 years - What should I do before startin

If it isn't siezed, I would certainly shoot some WD-40 or some lubricant into the cylinders and turn it over for a few seconds with the kill switch activated. If it wasn't winterized, I may be tempted to add some extra oil to the first tank of fresh gas. I think your friends' advice about sitting for long periods of time with oil in the cylinders applies more to locked-up engines. You may also consider dropping the carb bowls to inspect for gunk before you try to light 'er up. No sense plugging up the jets if it isn't necessary!

 

[hondon]

Re: 1991 Mercury 150hp: Not cranked in 5 years - What should I do before startin

Re: 1991 Mercury 150hp: Not cranked in 5 years - What should I do before startin

Your buddies give some sound advice, but you maynot have to wait all that long. Remove the plugs and shoot some oil into each cyl. then turn the motor over by hand. This will allow you to feel for yourself if there are any tight spots in the rotation.After that I would consider disconnecting all oil lines to prevent rancid oil from entering your fuel system while looking further.Then do a cranking compression test and let us know what you find.You can expect some repairs to be needed in a motor that has been mothballed for this long.Waterpump and carb work are probably nessesary,but let's make sure the vitals are there first.

 

[flips]

Re: 1991 Mercury 150hp: Not cranked in 5 years - What should I do before startin

Re: 1991 Mercury 150hp: Not cranked in 5 years - What should I do before startin

hondon and fouled plug are right on<br />i let my 77 8o hp sit for 7 years<br />pulled plugs filled with wd 40 turned by hand<br />for a while clean carbs/ changed impella and found old one better than new one but still changed over started engine ran till warm and filled carbes with merc spray to de carbon rings ect let sit as directions put in water an ran flat out to clear motor and its still going strong 5 years later