I recently changed the oil on my newly acquired 1995 36mkII for the first time. I used a hand pump that came with the boat, sticking the plastic tube down the dipstick/oil fill pipe. The engine is a universal 30hp. It was really hard to get much oil out. There was simply a lot of resistance as if I were trying to pump thick mud instead of oil. After about forty-five minutes of trying, I had gotten about half of the advertized capacity out and I quit. Was I doing something wrong or it this just a tougher task than I had expected? Would a pump with an integral tank make it easier? The pump seemed to unobstructed and in good working order. I did not run the engine to heat up the oil beforehand, but it was about 90 degrees out that day. Thanks in advance for your help. Charlie
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Ron Dague
Vacuum
Did you loosen or remove the oil filler cap? The vacuum created when pumping the oil out, without loosening the cap can make it almost impossible to pump. Been there, done that. I would think that even at 90 degrees ambient temperature, running the engine would be a good idea. Viscosity will go down even more, but I've never tried it without running the engine, so I really can't compare.
Did you loosen or remove the oil filler cap? The vacuum created when pumping the oil out, without loosening the cap can make it almost impossible to pump. Been there, done that. I would think that even at 90 degrees ambient temperature, running the engine would be a good idea. Viscosity will go down even more, but I've never tried it without running the engine, so I really can't compare.
Gotta warm them up.
Charlie: Always warm your engine up before you change the oil. The best way to do this is to be sure that you are secured to the dock (assume that you are at a dock) and start your engine. After you have proper oil circulation in the engine, put it in gear and rev it up to 1000-1200 RPM. This will put load on the engine and cause it to heat up faster. Once you think it engine is very warm, you can shut her down and try pumping the oil. I know that you think that it is warm out and you should not have a problem but look at the new oil that you pour in. It pours pretty slow. I think that this will help. Also make sure that you are getting the tube to lowest part of the pan. Must of these engines tilt to the aft of the boat. Good luck on your next oil change.
Charlie: Always warm your engine up before you change the oil. The best way to do this is to be sure that you are secured to the dock (assume that you are at a dock) and start your engine. After you have proper oil circulation in the engine, put it in gear and rev it up to 1000-1200 RPM. This will put load on the engine and cause it to heat up faster. Once you think it engine is very warm, you can shut her down and try pumping the oil. I know that you think that it is warm out and you should not have a problem but look at the new oil that you pour in. It pours pretty slow. I think that this will help. Also make sure that you are getting the tube to lowest part of the pan. Must of these engines tilt to the aft of the boat. Good luck on your next oil change.
and suck it out.
Charlie: Did not pick up on the fact that you were using a hand pump. I think that there have been a few comments on these had pumps. Most owners do NOT like them (and you probably know why now). I have used one of these vaccum units. You pump them up and it just sucks the oil out of the pan. I liked this unit. There is also a unit that mounts on the top of a 5 gal bucket. The pump looks just like your pressurized water pump. You hook to the battery terminals and it just pumps away (these are the best). So in addition to warming up the engine, try borrowing another type of unit and find out what works for you.
Charlie: Did not pick up on the fact that you were using a hand pump. I think that there have been a few comments on these had pumps. Most owners do NOT like them (and you probably know why now). I have used one of these vaccum units. You pump them up and it just sucks the oil out of the pan. I liked this unit. There is also a unit that mounts on the top of a 5 gal bucket. The pump looks just like your pressurized water pump. You hook to the battery terminals and it just pumps away (these are the best). So in addition to warming up the engine, try borrowing another type of unit and find out what works for you.
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Eric Lorgus
Oil temp matters, not crankcase vacuum
Charlie: First time I tried to change the oil on my Yanmar 2GM20F, I had a similar experience, although I was using a vacuum can, and the engine oil was merely warm, not hot. Second time I tried, I made sure the oil was hot! This time, the oil sucked out like water, instead of syrup the first time. I've heard this business about opening the oil fill to avoid a "vacuum" when removing old oil. Most internal combustion engines have ventilated crankcases, and removing oil should never create a vacuum in a ventilated system. I suppose opening the fill wouldn't hurt, but I never have.
Charlie: First time I tried to change the oil on my Yanmar 2GM20F, I had a similar experience, although I was using a vacuum can, and the engine oil was merely warm, not hot. Second time I tried, I made sure the oil was hot! This time, the oil sucked out like water, instead of syrup the first time. I've heard this business about opening the oil fill to avoid a "vacuum" when removing old oil. Most internal combustion engines have ventilated crankcases, and removing oil should never create a vacuum in a ventilated system. I suppose opening the fill wouldn't hurt, but I never have.
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Charlie Allen
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