Crankcase pressure

IH10020 · Mar 26, 2022

Cub cadet 2185, 18 horsepower Kohler seems to have a lot of pressure when you remove the oil filler cap is this normal? Thanks

Mule Meat · Mar 26, 2022

A blown head gasket is the number one cause of excessive crank case pressure.

Smokes alot while running - Blown between piston and rocker cover area.

Blows oil out of the dipstick, fuel pump (vacuum type) and case vent - Blown between exhaust valve and rocker cover.

A few years ago Kohler sent out a large number of engines with defective head bolts that were known to blow head gaskets. Can't say if they still do. But for a time they would send you a new gasket set with new head bolts free of charge.

Other causes of excessive pressure can be caused by worn piston and rings, cracked piston or broken rings.

IH10020 · Mar 26, 2022

Thanks for the info, I appreciate it.

Blackhole49 · Mar 27, 2022

You should be able to do a compression test for a bad head gasket. I had a 16 hp Onan in a Case 446 that was blowing oil into the carb through the crank case vent. Ran good but smoked. I was a bad front crank seal.

wore out · Mar 27, 2022

(quoted from post at 10:21:38 03/26/22) Cub cadet 2185, 18 horsepower Kohler seems to have a lot of pressure when you remove the oil filler cap is this normal? Thanks

What is the engine model?

Are you opening the oil filler while it's running? If so WHY?

Or does a have crankcase pressure for a bit when shut down?

Are there any other symptoms of excessive crankcase pressure such as oil leaks, oil burning, smokey exhaust, etc.?

IH10020 · Mar 27, 2022

Just replaced front crankcase oil seal and
changed oil and filter. Hadn't got the
filler cap back on yet it just seemed like
a lot of pressure to me, engine runs well,
doesn't smoke or loose power.

wore out · Mar 27, 2022

(quoted from post at 13:38:10 03/27/22) Just replaced front crankcase oil seal and
changed oil and filter. Hadn't got the
filler cap back on yet it just seemed like
a lot of pressure to me, engine runs well,
doesn't smoke or loose power.

So, to be clear, you started it with the oil fill cap not installed?

If that's the case, most any small engine will spew if started without the cap, the crankcase ventilation system can't work properly with the cap "off".

Gene Davis (Ga.) · Mar 30, 2022

Kohler usually reccomends that these engines have a vacuum in the crankcase of~3-4 inches on a manometer scale. I worked on one in a John Deere 150 Hydrostatic lawn tractor that had been to about every shop and shade tree guy in the county including the Deere dealer. It was smoking, blowing oil out of the crankcase into and filling up the valve cover, air filter connection to the carburetor with oil then finally fouling out the spark plug. The lady got tired of fooling with it and spending money for folks to not fix it and just gave it to me. After a couple of rounds trying everything I knew about I finally tore it down and upon very close inspection and measurement I determined the exhaust valve lobe on the camshaft as worn ~ .3000 of an inch so that it was barely opening the exhaust valve so the exhaust gas was pressurizing the crankcase to about 10# or so because it could not go out the exhaust valve. I replaced the camshaft and lightly relapped the exhaust valve and now it pulls ~ 3 inches of steady vacuum on the manometer. The manometer tube is inserted in the fill opening with the correct adapter to measure vacuum.

PJH · Apr 25, 2022

I have an 18 hp Kohler that blew out the crankshaft seal. I also thought the crankcase pressure was high, and I discovered that it had been assembled with two reeds in the ventilator valve. I replaced them with one new reed, and so far so good for the last 5 or 6 years.

Crankcase pressure

IH10020

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Mule Meat

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IH10020

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Blackhole49

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wore out

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IH10020

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wore out

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Gene Davis (Ga.)

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PJH

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