Running engine without lower unit

[tidelee10]

I want to remove my lower unit and work on it over the winter (change water pump, lube etc)
Can I start my 2012 Yamaha f150 without the l/u just to circulate fresh oil when I change the crankcase oil? I realize you wouldn't want to run it for too long and overheat it...just want to know if I could screw something else up ...thanks!

[robert graham]

How can you do that since the water pump is on the lower unit?....I personally wouldn't do it....

[tidelee10]

I don't have access to water......water line broke at the vacation house and cant hook hose up to motor...would just run it without the lower unit attached for about 15-20 seconds to circulate fresh oil thru the motor...

[zenoahphobic]

I don't have access to water......water line broke at the vacation house and cant hook hose up to motor...would just run it without the lower unit attached for about 15-20 seconds to circulate fresh oil thru the motor...

You could have a raised water container like a camp shower attached to your flushing connection on your cowling if you have one.

[fairdeal]

I thought, with the lower unit off, there would be nothing turning the oil pump...

Are there Yamaha 4-strokes where the main driveshaft does NOT turn the oil pump?

[boscoe99]

Most of the bigger Yams use the crank shaft to turn the oil pump. Not the drive shaft. The F150 is one of those.

Smaller motors use the camshaft to turn the oil pump. A few do use gears on the drive shaft to turn the oil pump.

I don't see the motor over heating if being run without water for less than a minute. Certainly the water pump won't be damaged since the lower unit will have been removed. But then there is the issue of condensation being formed with the temperature of the oil never rising to the point that it can evaporate the moisture.

Why not pull the kill switch and simply crank the motor to circulate the oil. Just take care not to let the starter motor over heat. 20 seconds should not hurt it. If the spark plugs are removed there will be less load on the starter motor and the engine will crank at a faster RPM, pumping oil more quickly.

[tidelee10]

That is exactly what I want to find out....would the engine be self sufficient without a l/u attached? I don't remember seeing anything in the schematics where the l/u shaft operates anything besides the water pump and gears in the l/u...Thanks for the assistance!

[tidelee10]

Thanks Boscoe99! Good idea!!

[TownsendsFJR1300]

i was checking my F150 shop manual and the oil pump runs off the crankshaft(as noted above).

[tidelee10]

Thanks! I appreciate the help

[TownsendsFJR1300]

Something you may consider when cranking over with the plugs out.

Put a a couple of teaspoons of SEAFOAM into each cylinder to coat and protect all shiny surfaces. Just make sure the engine is spun over enough with the plugs out as to NOT cause a hydraulic lock..

[rodbolt17]

this motor?
fire it off let it run a few minutes.
wont hurt anything.

[tidelee10]

Thanks everyone! I appreciate your help!