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GregB

AC 716 Kohler Head Gasket replacement aftermath

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GregB

Couple of weeks ago I pulled the head of the 716-6 I have had for 12+ years. After cleaning the minimal carbon, and replacing the head gasket now it is difficult to start, and some times backfires going thru the start-up. And sensitive to throttle position until warm.

OEM Kohler gasket torqued to Service manual specs in correct tightening sequense.

Any clues as to why?

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MikeES

Small piece of carbon stuck under a valve? Preventing a tight seal, which can blow hot exhaust back into the intake and cause a backfire or allow unburned fuel to leak into the exhaust muffler and later ignited.

Just tossing that out there?

I also thought about if the new head gasket is interfering with the valves, but decided that would be very unlikely.

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sliderxc
quote:Originally posted by MikeES

Small piece of carbon stuck under a valve? Preventing a tight seal, which can blow hot exhaust back into the intake and cause a backfire or allow unburned fuel to leak into the exhaust muffler and later ignited.Just tossing that out there?I also thought about if the new head gasket is interfering with the valves, but decided that would be very unlikely.


id="quote">
id="quote">have to agree must be carbon causing valve not closing all the way this would give the backfire and sensitive throttle due to a vacuum leak

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GregB

Pulled the head yesterday. Found an oily kind of deposit on piston top and part of the head?

As far as cleaning valve seats, any way other than just rubbing them with a hard wood stick?

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MikeES

I have cleaned the valve area by having the valves closed and using a dental pick on the area around the valves. The closed valve prevents the pick from marking the actual valve seat area, but still really clean the recesses around the valve. Then open the valves and check the seating surfaces really good, I have never had anything on the valve surfaces.

But usually while I have the head off I lap the valve seats and reset the tappet clearance.

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GregB

Thanks guys.

Today I finally got back on this. Put a piece of scotch brite between the valve and the seat. Spun it around to clean on both valves with a partially closed valve.

Cleaned off the head and block faces, and re-torqued the head gasket at slightly above spec torque + 3lbs.

WOO HOO :D

Started like it used to, choke and low throttle, and immediate off on the choke, smooth idle at low RPM's.

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