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

[zmister11]

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.

Yeah i do the same

 

[Elendil]

Interesting thread.

Just to throw in my 2 cents: Just got done reading my owners manual for my new Z723KH. Here is a direct quote: "After slowing the engine to half speed, turn the key switch to the OFF position"

There is also an additional note at the bottom of the same page: "Place the throttle control lever in the half speed position to help prevent the engine from backfiring before stopping the engine"

 

[exotion]

I think its all a bunch of hullabulloo :/ just turn the machine off speed doesn't matter. What you don't want is to turn the machine then start it back up within a few seconds

 

[arielredhunter2]

I think its all a bunch of hullabulloo :/ just turn the machine off speed doesn't matter. What you don't want is to turn the machine then start it back up within a few seconds

We are all welcome to think whatever we wish. This makes as much sense as starting your car in the winter time, leaving the driveway, and accelerating to 70 mph with a cold engine on a 20 degree morning. An engine is composed of a group of different metals, all with different rates of contraction and expansion.

 

[LazerZLandscaping]

I just shut the mower off and then bring the lever all the way down

 

[Diwali]

Yes. I have no idea what the manual says but my Craftsman LT2000 backfires loudly if I don’t. Sometimes it does it even with the throttle at minimum but considerably less often than when I shut off at a higher throttle.

 

[Gord Baker]

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?

It is important to give Air Cooled and Liquid cooled mower engines a short cool down period and wise to idle down the engine before shutting off the Ignition.
This prevents raw gas from washing lubricant from cylinder walls and weeping into the crank case. If you notice, the engine makes several revs after Ignition is turned off, sucking in raw fuel. The electrical shutoff does not prevent this from happening in most if not all cases.

 

[rascal1]

Letting the engine idle cools down the exhaust valve. The only cooling the exhaust valve head gets is when its closed on the power stroke when under load. At idle it has longer contact with valve seat transferring heat.

 

[Michiglenn]

It is important to give Air Cooled and Liquid cooled mower engines a short cool down period and wise to idle down the engine before shutting off the Ignition.
This prevents raw gas from washing lubricant from cylinder walls and weeping into the crank case. If you notice, the engine makes several revs after Ignition is turned off, sucking in raw fuel. The electrical shutoff does not prevent this from happening in most if not all cases.

I agree with this. Without ignition to fire the mixture, the cylinder walls and rings are being washed with raw fuel (unless fuel injected). This is not a good practice for carbureted engines. Letting the engine idle for a couple minutes or so will cool the exhaust valves and draw very little raw gas when shut down.

 

[Rob47]

For me it is a habit to idle the engine down before shut-down - it represents the reverse of starting an engine at full throttle just because of momentary delay of oil delivery to the bearings on an automotive engine. So in this case it is meaningless.
The other reason I will idle it down is one of determining where new bearing noises might be coming from. Since there is a number of pulleys on riding mowers that control and tension belts, it will allow me to HEAR any new noise that has developed once the engine has slowed down to an idle. Many owners are not aware of bearing noise until it starts to scream or seize. In some instances this can also tear up a belt. I will also periodically remove the deck drive belt(s) to hand spin the spindles to see if they are generating noise. I will choose to replace the bearings in the spindles rather than buy the whole spindle assembly from the dealer. If delayed, the bearings will seize and tear up the spindle casting and force the replacement of the assembly.
If you are not a mechanic and have a shop with adequate tools, then this procedure is not ideal - just pay the money and buy the whole spindle assembly.