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Lost Compression

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#1 Kevin Vasich OFFLINE  

Kevin Vasich


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Posted March 31, 2013 - 08:25 AM

Hi, I had the 812 running and driving for 2 hours, then I asked my friend to go get the trailer. Then the tractor just stopped. I walked over and then we pushed it in the the garage. I took the spark plug out to see if the piston moves then I put the spark plug back in. Why would it feel like it has no compression with the spark plug in? I know these kohlers have compression release in them. I don't know where to start.

#2 drbish ONLINE  



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Posted March 31, 2013 - 08:36 AM

I would take the head off and make sure your valves are working correctly

#3 Guest_gravely-power_*

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Posted March 31, 2013 - 08:38 AM

Even with the compression release you should still feel some compression. Did you ck for spark and fuel. Could be a stuck valve.

#4 HowardsMF155 OFFLINE  



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Posted March 31, 2013 - 09:25 AM

This is the Kohler engine, right?  And it sounds like your piston is moving, though you did not specifically state that.  I'd be looking at the valves also.  Tentative guess is maybe a screw from the carb got sucked into the engine and is caught between the valve and it's seat.  Check the carb for missing screws and pull the valve adjustment cover to see if the valve stems are moving up and down.


Edit:  IIRC, the Kohler engines can be checked for compression by rotating them in reverse.  You won't get a compression reading that way, but should be able to get a feel "by hand" for basic compression.

Edited by HowardsMF155, March 31, 2013 - 09:31 AM.

#5 HDWildBill ONLINE  


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Posted March 31, 2013 - 10:36 AM

Even with the compression release you should still feel some compression. Did you ck for spark and fuel. Could be a stuck valve.


That's what I was thinking a stuck valve.

#6 boyscout862 OFFLINE  

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Posted March 31, 2013 - 11:07 AM

The easy way to check the valves is to pull the plug. Bend a wire and push it through the plug hole. Place the wires end on a valve and turn the engine. If a valve isn't moving fully, there is your problem. I would suspect a valve keeper coming off. That happened to me twice last year on two different B&S engines. Good Luck, Rick


If it is a stuck valve, spray some WD40 at it and push it down with a small bent rod through the plug hole.

Edited by boyscout862, March 31, 2013 - 11:09 AM.

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