Oil & Fuel 24 hp onan oil pressure

[Wlighty23]

My 24 hp Onan has good oil pressure at high rpm's. at idle the pressure drops to zero and the gauge will occasionally flicker. Oil pressure switch? Gauge? Any help will be appreciated.

[don45640]

When I see that in the automotive world,or large engine world,I put a pressure gauge on it and check it. If you are using really lightweight oil,it can cause this.
I had an old worn out 6 cyl. Ford Fairmont that the light would flicker on at idle. Because I used it to get to work every day(50 mi. round trip),and it didn't burn any oil, I just switched to 15W40 for diesels and ran until a deer bent its frame(unibody).
So if you're using some 5W-30,you might go to 10W-30,but I'd check the true pressure first. don-ohio (:^)

[hr3]

Small Engine Technical Forum :: View topic - onan 24hp wont run without battery

[Wlighty23]

Thanks Don. I have a dumb question. Would this motor have the low oil pressure shut down? This motor is a transplant in my skidsteer. It runs great no knocking or smoke. I would think it would have started knocking or something with no oil pressure. Thanks for any ideas. Wlighty

[lsmurphy]

If you are using a Fram oil filter, change to Napa Gold.

Move to straight 40W oil.

[Wlighty23]

I live in MN. Will that be a problem in cold temps? The machine is not in a heated shop.

[lsmurphy]

I live in MN. Will that be a problem in cold temps? The machine is not in a heated shop.

I wont' make that call for you.......and I don't live where temps get to 0.

Your main and rod bearings are worn to the degree that at low RPMs the oil bleeds out and pressure is lost. Multi weight oils are just too thin.

[crashz]

The grade of oil may be too light, but not all multigrade oils are to light. A 5w-40 and straight 40w will be the same viscosity at operating temperatures. Only cold temp viscosities are different. Forty years ago multigrade oils would shear out of grade or gum up due to the polymers used, but not so today. Now they offer superior performance over straight weight oils.

I'd check the pressures first with a good gauge.

[jaotguy]

Ditto on the gauge... but try the 15W40 first .....

don't forget about synthetics even wider ranges and better suited to heat variations. could even go higher than 0W-40 .

minimum PSI at idle should be 10 PSI you need 7 PSI for each 1000 RPM to keep bearings lubed properly when hot and running.

[Wlighty23]

Thanks, as soon as it warms up a little I will take a manual pressure check. I think 40 synthetic will be my next oil of choice.