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Blackhood Bill

Blowed spark plug

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Blackhood Bill

Ok my question is this. Spark plug blew out, dad replaced head, spark plug blew out with used head, put heli-coil in, spark plug blew out again! Tonight pulled head gasket looks good. Would you replace gasket and what would cause this? What needs to be checked and where to start? Pics of gasket with head off attached. Any all help appreciated due to snow has finally arrived. Ordered new head and gasket. This is on a C-145 hydro, Kohler 14 hp K321AS engine  with proper spark plug H-10

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Edited by Whnewone
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oliver2-44

@Whnewone Please share a little more information. What tractor and engine is this, and what brand & part # spark plug are you using.  Is there a chance you are using an incorrect plug.   

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ztnoo

That's pretty strange.

Never heard of that problem before ..... even in Indiana.

;););)

 Especially in Howard County!

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Blackhood Bill

This is on a C145 hydro 14 hp Kohler K341 AS engine with H-10 spark plug.

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ztnoo

A K341 is 16 hp.

 

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richmondred01

Also check the reed valve assembly. You may have too much pressure build up along with bad plug threads.

also make sure the oil drain hole on the cover is facing down.

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Blackhood Bill

 Oooops my bad it's a K321

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c-series don

I don’t know the answer to this, but I want to!!

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The Tuul Crib

 Is it possible that the exhaust valve maybe sticking causing The spark plug to pop out?

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Howie

I would think the plug is not really tightening up as it should. Helicoil put in straight so plug seat correctly?

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Howie

If exhaust valve is not seating it would build less compression than if it was seating I would think.

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Blackhood Bill

To my knowledge yes had that installed by a mechanic who does nothing but work on garden tractor engines.

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ztnoo

The intake valve is open in the pic, so the combustion chamber would be "vented", although the wrong way. That wouldn't blow a plug out.

Unless both valves would not open, its either a problem with the heads (highly excessive compression ratio), the plug threading, or the spark plugs themselves.

Was the head torqued to spec?

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Blackhood Bill

That I don't know due to that was done before I even took possession of the tractor.

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Howie

:text-yeahthat: I'm still leaning toward the threads in the head or on the plug, because if it was making that much compression would be 

real hard for starter to turn it over.

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Blackhood Bill

Turned over fairly easy and fires right up

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Ed Kennell

Time for a compression check.       If the correct plug is seated in a good threaded hole, it would require over 200PSI to blow out the head threads.

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Blackhood Bill

After pulling head off the threads are now gone. Will have to do that when new head arrives. What should the compression be?

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Shynon

You will need to do a leakdown test, ACR will not allow for a compression test.  Has the block been sleeved?  Reason I ask is the ledge around the piston that is lower than the top of the cylinder and the piston if off center. Something just doesn't look right. 

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Blackhood Bill

If it has I don't know but that would something to look at for sure. Will have to take gasket off and clean it up for examination.

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lynnmor

Are you using starting fluid?

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953 nut
9 hours ago, Whnewone said:

After pulling head off the threads are now gone. Will have to do that when new head arrives. What should the compression be?

Sounds like the mechanic that installed the head owes you a refund on that job. Spark plugs stay screwed in to high performance engines with very high compression, they should stay in a good head on a Kohler. Your engine has an automatic compression release that makes the engine easy to turn over at low RPMs. 

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squonk
53 minutes ago, 953 nut said:

Sounds like the mechanic that installed the head owes you a refund on that job. Spark plugs stay screwed in to high performance engines with very high compression, they should stay in a good head on a Kohler. Your engine has an automatic compression release that makes the engine easy to turn over at low RPMs. 

:text-yeahthat:

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Blackhood Bill

No starting fluid. Never had to ever since I have had it.

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