Do You Throttle All The Way Down Before Turning Off The Engine?

[gfp55]

I have reread all the manuals I have for machines with engines on them, Onan, Kohler, Tecumseh, Briggs & Stratton, Robin, etc. All say that to reduce engine speed before turning off engine. I know there are some manuals that say to turn off engine at full throttle, but I think I will reduce engine speed before turning off engine like I have for over 40 years anyways. "But thats just me"

 

[Valtex]

This is a timely question for us. We just purchased a 60" Hustler Super Z HD/ kawasaki engine for residential use on a bit of acreage. The dealer and the owners manual states to idle down, however, when speaking with a Hustler rep regarding another matter, he stated this is "old thinking" and idling down should NOT be done. We noticed the engine backfiring a bit after shutting down and wonder which method Kawasaki currently recommends? Have they not updated their owner manual as it does say to idle down.

 

[Shughes717]

I used to idle down before shutting my Kawi fx series engine, but noticed it would backfire from time to time. My dealer instructed me to shut it off at full throttle. No more backfires.

 

[arielredhunter2]

I used to idle down before shutting my Kawi fx series engine, but noticed it would backfire from time to time. My dealer instructed me to shut it off at full throttle. No more backfires.

It's backfiring because it's hot. Under load, the exhaust valve is running a dull red. By running engine at 1/2 throttle, no load, it allows the engine to stabilize temperatures across the cylinder and head. Under load, the exhaust valve and ports run much hotter than the rest of the engine. Shutting off an engine that has been under load and is hot can easily lead to exhaust valve burning and sticking. Usually not right a way. After a year or two. You know, after the warrenty has run out.

 

[PJDudley]

Or, when you quit mowing, do you shut down the engine at full throttle and not concern yourself about it?

My old tractor style 46" deck, Craftsmen, powered by a 24 Hp, B & S Intek engine's manual never mentioned having to do this. So, I always left it going full blast when I killed the engine. I sold it to my next door neighbor with 350 hours on it and he is now running it with over 500 hours on it and he doesn't worry about shutting it down at idle.

My Toro manual says to idle all the way down, wait a minute and then turn off the engine.

What do you guys say?

I throttle down now because when I would shut down my 19hp Troybilt after mowing a couple acre at full throttle it sometimes would diesel
during shutdown. So before shutting down I would lower the throttle to about 3/4 for a moment and then shut down. Since then I've purchased a
new 24hp Husqvarna and I do the same with it just for good practice. Certainly can't hurt.

Paul

 

[Shughes717]

It's backfiring because it's hot. Under load, the exhaust valve is running a dull red. By running engine at 1/2 throttle, no load, it allows the engine to stabilize temperatures across the cylinder and head. Under load, the exhaust valve and ports run much hotter than the rest of the engine. Shutting off an engine that has been under load and is hot can easily lead to exhaust valve burning and sticking. Usually not right a way. After a year or two. You know, after the warrenty has run out.

It would still backfire after I let it idle for several minutes though. I know we have always let our diesel tractors idle before shutting them off after a day in the fields to let them cool off. Continued that practice with the mowers I have owned. The Kawi is the first one that backfired with me. It didn't make sense to me to shut it off at full throttle, and I couldn't find instructions on the proper shutoff procedure in the manual. It hasn't backfired since I have started shutting it off at 3/4 throttle. I hope I'm not damaging anything. I am counting on this mower to last me another 15 years or so.

 

[arielredhunter2]

It would still backfire after I let it idle for several minutes though. I know we have always let our diesel tractors idle before shutting them off after a day in the fields to let them cool off. Continued that practice with the mowers I have owned. The Kawi is the first one that backfired with me. It didn't make sense to me to shut it off at full throttle, and I couldn't find instructions on the proper shutoff procedure in the manual. It hasn't backfired since I have started shutting it off at 3/4 throttle. I hope I'm not damaging anything. I am counting on this mower to last me another 15 years or so.

I don't think you are going to hurt it the way you are doing it, as long as you run it for a few moments to stabilize temperture. Like driving it to the toolshed at 3/4 throttle ought to be long enough.

 

[Carscw]

A mower engine cools down fastest when it is running at full throttle.

Driving around the yard to cool it off at 1/2 or 3/4 throttle is doing more harm then good to the engine and the hydros.

 

[arielredhunter2]

A mower engine cools down fastest when it is running at full throttle.

Driving around the yard to cool it off at 1/2 or 3/4 throttle is doing more harm then good to the engine and the hydros.

Interesting thought. However, I've been doing just that for the past 30 years with my Cub Cadet 147 Hydro with no ill effects. Engine has been honed and re-ringed once. I don't believe in boring side valve engines. Causes more heat distortion on the exhaust valve side.

 

[Shughes717]

I don't like the sound the hydros make when moving at less than full throttle. It whines more. I don't move it unless I'm at full throttle. There are so many different opinions on the proper way to shut the engine off. It is very confusing.