Kohler Command 27Hp valve problems

Old 09-18-19, 05:40 AM
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Kohler Command 27Hp valve problems

I have a Kohler CH750-0026 engine on my Toro zero turn mower. The cylinder on the left has always fouled sparkplugs, burned oil, and I think is the reason why my oil is black. The cylinder quit the other day while mowing. I took off the valve cover to find that both rocker arms had somehow slipped off of the valves. I also see that the intake valve has a valve seal but the exhaust valve has no seal. Is the exhaust valve not supposed to have a seal on the top of the head or is that the cause of the cylinder burning oil because the seal is missing? Also, I don't see any adjustments for the rocker arms. Are they just warn and need to be replaced which is how they slipped off of the top of the valve springs?
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Last edited by trametta; 09-18-19 at 06:17 AM.
Old 09-18-19, 10:13 AM
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There should be no seal on the exhaust valve. The rocker arms have no adjustment, the lifters are hydraulic. It's probably burning oil on that side because of rings and/or head gasket issues. The rocker arms falling out would be because the valves stuck open or lifters collapsed. Usually because the valves stuck open from heat or shellac on the stems from running old gas.

Last edited by cheese; 09-18-19 at 10:32 AM.
Old 09-18-19, 10:21 AM
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Hydraulic lifters so hydraulic pressure maintains everything. You may have ran out low on oil or the oil pump may be under performing. That lets the lifters bleed down and the extra clearance would let them off the valve stems.

No seal on the exhaust valve stem. The heat would wreck a seal like you see on the intake valve. On the exhaust when the stem is exposed to air flow there is pressure on the underside of the stem run. There's nothing to pull the oil down past the stem.

On the intake valve you have vacuum on the intake stroke. That valve runs cooler so you can put a seal on the oil end.

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