Small engine crankcase flushing?

[Steelhead]

how many flush their small air cooled crankcases when doing an oil change with Rislone, diesel, gas on lawnmower and tiller used in dusty areas?

i've been doing it for years, amazing how much dirt comes out with the flush
fill with a qt or two after draining hot oil out and slosh around, drain out into drain pan
do NOT run with the flush in

 

[mtgrs737]

Steelhead,

I like to flush out the crankcase on my small engines with mineral spirits. I think that it is a good idea when the you do the first few oil changes when the engine is new and breaking in. I change my new engine's oil at 1 hour, 2 hours 5 hours then after every 10 to 12 hours of use. On generators that are well broken in I will leave the oil in for up to 50 hours of running time. In an engine without a filter it is better to change out the oil rather than buy a new engine as oil is cheap.

 

[Bror Jace]

I wouldn't use any solvent of any kind in an internal combustion engine.

Fresh motor oils circulating through an engine will loosen up and "flush out" the most significant gunk. It may not be pretty to look at, but the important areas that see the most action will be clean. No need to risk using a solvent to flush things out. You are always going to have a fair amount of solvent residue left over ... and that will compromise your new oil when you refill.

My recommendation is a series of very short OCIs ... maybe 1-2 hours each. Drain hot and refill until the drained oil looks somewhat clear.

If hard pressed, I might use something like MMO ... 3-4 ounces in a quart sump. Run the engine for about an hour ... MAX! Then drain hot.

Still, I prefer to simply use frequent oil changes ... especially in engines with no filter. They only take a quart or less ... so why not?

 

[bob_ninja]

I usually have some clean but old oil left from cars. Run it for very short OCIs to flush. Simple.

 

[Cujet]

I have recently started flushing out new air cooled engines with solvent. I make sure to dry with compressed air. I have even used carb cleaner. I make sure to get oil on all the parts as best I can before starting. I never run with solvent in oil.

There is an incredible amount of debris in new air cooled engines after break in.

Chris