Kohler 25 HP popping from exhaust under load.

I think I have this fixed but wonder if anyone else has had this problem? It seemed as though it could have been a sticking exhaust valve. Ran some combustion chamber cleaner through it and the problem seems to have resolved. Will know better tomorrow when I mow for an hour.
 
I'd give it a drink of seafoam. Sounds like carbon buildup and seafoam will remove that while running.
 
I respect Seafoam but the stuff I used is a Ford recommended combustion chamber cleaner that does work miracles. Didn't work here. I've got something else going on. Only get the popping when the engine is hot and working. Sitting still at WOT with no load there is nothing going on. I am a Ford technician by day, small engine repair by night. I find module networking and electronic engine control less daunting than a small engine with problems. Anyone else seen this with an idea?
 
Courage engine.. Check the Intake and Exhaust valve lash.

Command.. Pull the oil dip stick and watch for smoke coming from the filler tube (yes).. Pull the plugs and check them (especially the right one, sitting on the mower looking forward). Blown Head gasket.
 
I have a Kohler command 25 hp that was backfiring under load. Backfired hard enough to bend some valves.
The problem turned out to be a loose electrical connection at one of the ignition coils. It got enough
current to fire under idle and light load, but would misfire at full speed and under load. Hope this might
be of help.
 
Got a chance to check it. No smoke but lots of pressure and oil blowing out the dipstick tube. Thanks Mulemeat. Got gaskets ordered.
 
I should have explain more about smoke coming from the oil dip stick tube. You will see a lot of it after the engine has ran until hot, shut off and then checked.. You will have a small amount of smoke which is normal. But with a blown head gasket it really pours out of the tube.


The best Kohler head gasket kit is OEM Part number [b:f34191f57e]2484104S[/b:f34191f57e].

The head gasket has metal that fully encloses the combustion chamber and oil passages. It also includes everything shown in the photo below. If you get two kits you will end up with an extra set of exhaust gaskets and intake O-rings. Kohler use to include a new set of studs to replace the head bolts. They no longer do that for they discovered the problem was in the head gasket design in stead of the bolts. So if you engine has bolts. Just reuse them. If it has studs use the new one with the new washers..

I must note that it takes two kits to do both sides (since you must tear the engine down for one. May want to go ahead and do both both sides while it is apart).

61RdYkJnzBL._SY355_.jpg



PS: Not many people know that the nuts for Kohler heads can be used for bar clamp nuts on a lot of chainsaws. I keep a few of them in the small tool box that hold my saw tools and files just in case..
 
Definitely did both sides. This thing was a PAIN to take apart mostly because of all the air ducts. Its done and its fixed. Don't want to do it again. Thanks again mulemeat.
 
Your Welcome IndianaSteve.

Glad to hear that you got it fixed. They are not real bad to repair. The first one is the hardest. A lot of them you can remove the heads without taking the exhaust tubes off (Husqvarna tractors for one) and some you have to loosen or remove the muffler (John Deere Tractors). I have it down to where I can change the gaskets in about 1 to 1 1/2 hours if I stay at it..

In 2005 I bought a new lawn tractor with a 27 hp Command Pro engine.It blew a head gasket before it was due its first oil change. The dealer gave me the "up grade kit" for free that came with new studs to replace the bolts which Kohler thought was the problem. They still were using the old "aluminum waffle" gaskets which lasted about five years. The new kits have a much better steel framed gasket to replace the waffle and gives a much netter seal and larger oil return openings. Thank kohler finally figured it out that the bolts were not the problem, but rather the gasket itself could not hold up to the heating and cooling cycles that the engines go through on lawn tractors.
 
What I did not like the most was the washer/nut torque with the stick-slip as I tightened them down. Hope it doesn't cause a future problem.
 
If you are referring to the washers spinning when you were torquing the nuts. It will not be a problem if they spin or not.


Just check the torque on them after a few heat and cooling cycles. I tell people to check the torque on the head bolts/studs when they do the next oil change after a gasket replacement.
 

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