Oil shut off switch?

Geo-TH,In · Dec 23, 2013

I have a few with small engines with the oil shut off. I would like to know how the oil shut off switches work on small engines. When I change oil on a 20 hp kohler, it won't fire until the oil filter is full. I have a genny and 13 hp honda without oil filters. My honda has gismo 1 attached to the crankcase. Gismo 1 has a wire going to gismo 2. A second wire leaves gismo 2 and attaches to the coil. I'm guessing that when there is no oil in crank, the coil is shorted out by the gismos killing the spark.

So, what do you call gismo 1? Gismo 2? And how do they work? What do they use to detect the presence of oil?

Does my 20 hp kohler command use a pressure switch or does it use gismos like above?

All mine are working just fine, I'm just courous in the event they fail?
George

Tom from Buckeye Lake · Dec 23, 2013

I have an old Onan generator that has a pressure switch screwed into the engine block. It monitors oil pressure. Being an old unit, the pressure switch wire goes to the points and I need to crank it, just like you, for a few seconds until it starts. The pressure switch grounds the points until a few pounds of oil pressure is built up.

The pressure switch saves the engine bearings if you would lose oil pressure while running.

dpendzic · Dec 23, 2013

perhaps your gixmo's are similar to my hot tub water sensors. The sensor is on the outside of the fiberglass wall and emits a signal thru the wall--water disrupts the signal and it sends info to a relay that allows the jet pump to come on

T.R.K. · Dec 23, 2013

I just worked on a Honda 13 hp that had a float-type oil sensor. As long as the float floats in the oil it runs. The 'canister' thingy on the side of the engine is an electronic switch that allows it to crank, but will promptly stop the engine if its not getting the right signal from the float inside the crankcase.

I would assume your Kohler is looking for oil pressure if it won't run until the filter is full. There is probably a pressure switch on the engine near the oil cooler or filter.

One thing: those float-type switches in the Honda are sensitive to being operated with old oil in them. It causes the float to stick, most times in the low-oil position.

Billy Shafer · Dec 23, 2013

A Kohler that big should have a pressure switch on it. Kills the ignition on loss of oil. Some small engines do use a float switch in the oil pan. But the float switch has caused many problems. Caused so many for Onan. They dropped them.

Geo-TH,In · Dec 23, 2013

t.r.k.
Is it safe to say, when oil is present, the float switch is open and the gismo 2, electronic switch, is also open when you are cranking the engine? Then, after engine is running and the oil gets low, the float closes and so does gismo 2, shorting out the coil?

If I got it right, Then for testing purposes only, could a person just remove the wire going to the coil and engine would run without oil level protection?
George

Jeff NWOH · Dec 23, 2013

I believe that is correct. The level sensors short the coil to kill the engine. Disconnect and it should run.

Billy Shafer · Dec 23, 2013

Yes that would work. Unless they have the ignition wired thru the switch. I have seen some like that but not many.

T in NE · Dec 25, 2013

If you put one in a go-cart, it will also shut the cart off upon making a right turn, until you by-pass it.

Robert Major · Dec 25, 2013

Hi
They don't like being mounted on HY Trux crop sprayers to drive the spray pressure pump either. The guy I worked for had a 13 hp honda it would kill the motor on rough ground as it thought the oil was low.
The only problem with disconnecting the switch came the days he forgot to check the oil.
The switch working would of saved the cost of the new motor, when it seized solid at full revs and spat parts all over the field.
It was my fault it happened, until I pointed out I was away for 4 days, so he had run the sprayer and never checked the oil!, it needed topping up a little every 2 full days work.
Regards Robert

Geo-TH,In · Dec 25, 2013

Many moons ago, like almost 20, my son just had to have a go-cart. I found him one that someone put a 5 hp briggs where the gas tank was attached to the carb. The go-cart was a solid frame, ruff as a cob. If you got going too fast in the yard, the gas would vibrate out of carb back to the tank. So for a few seconds, the engine would sputter, cart slowed down until the fuel pump in carb filled the carb again and away he went. Nothing you could do about it, but it was a nice speed regulator.

Oil shut off switch?

Geo-TH,In

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Tom from Buckeye Lake

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dpendzic

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T.R.K.

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Billy Shafer

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Geo-TH,In

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Jeff NWOH

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Billy Shafer

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T in NE

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Robert Major

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Geo-TH,In

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