This is driving me nuts

[4-Leaf]

I have a Toro Z - 27hp Kohler. It's always been great.

The other day I was working and noticed a change in the pitch of the sound ... it sounded muffled ... as if suddenly the muffler was blocked up or something. It didn't really sound like it was missing or anything. It just sounded like it had put on an extra pair of hearing protectors.

Anyway, I keep working ... all of a sudden ... it lost about half its power. So I disengage the blades ... still felt like half power. After a couple of minutes it went back to full power. It's been doing it off and on. Sometimes it starts up like that. Sometimes it starts up running fine and then loses power.

I've pulled both plug wires off while it's running and it still runs. I changed the fuel filter and spark plugs -- no difference. I'm really baffled by the change in the sound.

I've searched the forums -- I'm stuck.

Anybody have a similar experience or any ideas?

Thanks

[mcambrose]

sounds like a head gasket to me.

[MowerMedic77]

Sounds like a baffle in your muffler may have broken free and is blocking your outlet.

[Restrorob]

Gotta agree with MM, Sounds like the ole broken baffle is what's baffling you.

[ricky86]

Wow. It ran with both plug wires off? What are you complaining about.

[PROCUT1]

You most likely have a coil or a plug going bad. That would explain the intermittant problem.

Try pulling the wires again when it does it. You may have just caught it when both cylinders are running.

Start it up at night or in a totally dark area and wiggle the plug wires and see if they are arcing on anything. That would cause the problem also.

If you have a bad coil the engine should shut down when you pull the opposite wire. Same as with a bad plug.

If that doesnt happen while you are still having the loss of power, most likely you have a wire that is arcing through the insulation.

[4-Leaf]

Ok, thanks everyone for the responses. Here is the story.

1 - The weird sound is being caused by a hole in the muffler. I still haven't seen the hole but while I was messing with the plug wires, I felt the hot air escaping (blowing out) on the wrong side of the muffler (opposite of the actual exhaust.) Hard to believe it's actually quieter than normal but the next item may be the cause.

2 - PROCUT, you were right, I originally tested it when both cylinders were firing. This morning the mower lost power an I immediately jumped off and pulled the wires while the power was still lost -- found it on the first try. I'm glad I read your post again because, when I pulled the wire and the engine died I immediately thought the one I pulled (that caused the engine to stop) was the bad side. Now that I reread your post, I realize it's the opposite one. I wouldn't have thought about it again if I hadn't come back here to post the results and reread your post. That would have been BRUTAL. The thing is, I should know better but I just jumped to a conclusion.

By the way, the symptoms are now more of a classic coil problem ... runs fine until it heats up and then fails ... doing it with regularity now. I also think it is possible that the coil is mostly bad all the time (not getting full power) and then completely fails when hot. I believe this may be the cause of the muffled sound.

Anyway, thanks again everyone. Your responses gave me things to check and let to the problem being solved. I'm back to sane again. I'll be changing the coil out soon and if it's still acting up, I'll repost.