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Discussion Starter #1
So I've had somewhat of a friendly disagreement with someone about cooling procedures on air cooled engines. Someone had made a suggestion that turning the engine off at wide open throttle on a D series tractor will stop backfiring problems. Sure maybe it will but that IMO isn't a good remedy for the problem.

The only backfires I've had was when the engine was shut down while it was to hot. The remedy is to propery cool your engine before shutting down. For me that is running the engine at just under a half throttle for a minuet or so to allow cool airflow over the engine after a hot run of work. To back me up the X series owners manual explains to run at half throttle for a moment before shutting down. Why?...to allow cooling. Furthermore, the Kawasaki FH manual has a WARNING about shutting hot engines down that it can and will cause engine damage. Why....because a hot air cooled engine gets hotter after shutdown.

So after I explained this I was told to argue with the D series owners manual. What????? Why would the D series manual say any different??? I have a theory on why it doesn't but I will wait and see what you guys think the reason is first. I will say this though...the web is scattered with residential mower engine failures, cracked blocks, ect ect. Mostly Kohler courage and Intek engines. Could the lack of proper cooling techniques in their owners manuals and ill informed operators be the culprit?? Ill let you decide
 

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I have install a temperature gauge on mine last year, (read the oil temp) and I can confirm that running the engine at haft throttle for few minutes bring the heat down.

Further more it should have a shut off fuel solenoid on the carburetor to prevent backfiring. :dunno:
 

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If timing is fine the backfire is more from being over loaded with fuel at the moment of shut down plus being at operating temp. I typically run gas air cooled engines at idle or just above for about a minute when they just got done working hard. This allows the engine to cool and to burn any excess fuel off. Many have a fuel solenoid as mentioned to help counter this problem. Even water cooled engines have a temp spike just after shut down as that's hard to avoid. My neighbor has a zero turn Dixie Chopper and he goes from full throttle and running. He hits the brakes, drops the throttle, and then shuts down. It backfires every time and I have mentioned a slower shut down but they still do it?
 

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My experience with air cooled VW, Porsche and Airplane engines is to definitely let them idle for at least a minute before shutdown, this allows for air circulation over the cylinder heads. Even a pinhole in the fan shroud of a Porsche air cooled engine disrupted the air flow enough to notice a difference.... In my Deere's case I leave it idle long enough to open the barn doors and put out the ramps.......
 

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The one thing I will say is that you will get alot more cooling at hi idle than at low or mid idle. The physics of centrifical fans is that if you idle the engine to half speed, you only get 1/8 of the cooling. I believe that's why the JD manual says to leave the engine run at full throttle with no load.

steve
 

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Discussion Starter #6
The one thing I will say is that you will get alot more cooling at hi idle than at low or mid idle. The physics of centrifical fans is that if you idle the engine to half speed, you only get 1/8 of the cooling. I believe that's why the JD manual says to leave the engine run at full throttle with no load.

steve
I have a X300 series manual in my hand right now and it does not say that. It's says half throttle. And so does the Kawasaki service manual

The problem I'm referring too seems to be that the D series manual contradicts the X series manual according to someone else. Why one would say full throttle cooling and the other half throttle is beyond me. I tend to believe the more detailed account of What Kawasaki says to do
 

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I have a X300 series manual in my hand right now and it does not say that. It's says half throttle. And so does the Kawasaki service manual

The problem I'm referring too seems to be that the D series manual contradicts the X series manual according to someone else. Why one would say full throttle cooling and the other half throttle is beyond me. I tend to believe the more detailed account of What Kawasaki says to do
I have a JD 100 series manual in my hand as well right now for my new D105 and it says on page 26 re: " stopping the engine " and I quote :

1. Let engine run at high throttle without load for a few seconds.

2. Turn key to STOP position. Engine will stop and headlights will turn off.


It has a Briggs and Stratton single cylinder engine in it, different from your Kawasaki engine, keep that in mind, because to your way of thinking owners should just ignore the JD manual and do what you say is what I'm reading out of these continual arguments you are bringing forth here and in other threads :coffee:.
 

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Discussion Starter #8
I have a JD 100 series manual in my hand as well right now for my new D105 and it says on page 26 re: " stopping the engine " and I quote :

1. Let engine run at high throttle without load for a few seconds.

2. Turn key to STOP position. Engine will stop and headlights will turn off.


It has a Briggs and Stratton single cylinder engine in it, different from your Kawasaki engine, keep that in mind, because to your way of thinking owners should just ignore the JD manual and do what you say is what I'm reading out of these continual arguments you are bringing forth here and in other threads :coffee:.
Excuse me?? Continual arguments?? This is a site for sharing information and ideas. We don't always agree and that's great...keeps things interesting. But to read into that way is a little thin skinned sir. And It is not my way of thinking...it is a way of thinking published by John Deere.

Well I did get one usefull thing from your post. The D and X manual do say 2 different things. The point of the thread is why would one tell one thing and the other something else. And not all D's have a single cylinder engine....alot have a large twin such as the D170. Air cooled twin is a air cooled twin, both cool the same way sir.
 

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As a D Series owner, I am immensely curious about the "right" procedure to follow, which in my case is what is in the manual. I guess the question is not about "air cooled Deere's" but more about different procedures as recommended by the engine manufacture (in this case Kawasaki vs. Briggs&Stratton). Could it have something to do with the engine specifics, electrical requirements, or even fan specifications? I don't know, but I do agree it is a good question and one that seems worthy for debate.
 

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I read a lot about shut down engine pops, they can be hard on the muffler.

I think that the engine can take it, as long as you don't go from full throttle heavy mowing directly to engine off, a little cooling is nice.

I have my own take on saving the muffler, those pops can destroy one!! :crybaby:

The carburetor operates two different fuel delivery systems, idle, and high speed.

My belief is the idle circuit is set to deliver a "rich" mixture, so that the engine will not stumble on "throttle up".

That is why no accelerator pump is needed.

The high speed is lean, to meet emissions, :fing32:

So, to shut off an engine without a POP, have the engine running fast enough to get a lean mix.

It works for me, I have totally eliminated the POP from 3 engines!! :bannana:
 

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To cool my tractors after mowing hard, I slowly slow down the engine, not just WOT to operating speed. I idle it for 15-20 seconds before I shut it off, and its perfectly fine. If I don't idle it, then it will diesel and backfire on the 214.
 

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Even my Kawasaki Liquid Cooled will backfire if i shut it down after an extremely long hot run.. so now I run it around with mower off for a minute @ high ground speed to get in the cool air. Then shut down ,( which it does after as short run after the key is off) i giuess Kawasaki wants to burn off any excess fuel first.
 

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I am so cool that just sitting on mine makes my tractor cool, ok well maybe it is the other way around, my x500 makes me cool.

Some good advice above, so you can ignore me.
 

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Like I said in the other thread...the fuel shutoff solenoid only works on the main jet circuit, so you must be above idle when shutdown to prevent backfire.

Today's engines are leaner than when grand pappy taught us all to idle down before shutdown. Things change.

This IS NOT engine temp related. I've discussed this at Kohler, Kawasaki, and Briggs service schools. All give the same answer...shut down at any throttle setting...but to prevent backfire be above idle.


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Discussion Starter #16
As a D Series owner, I am immensely curious about the "right" procedure to follow, which in my case is what is in the manual. I guess the question is not about "air cooled Deere's" but more about different procedures as recommended by the engine manufacture (in this case Kawasaki vs. Briggs&Stratton). Could it have something to do with the engine specifics, electrical requirements, or even fan specifications? I don't know, but I do agree it is a good question and one that seems worthy for debate.
They are air cooled internal combustion engines regardless of make and cool the same way. But that's a interesting point you make about different fan sizes. I think the Briggs inteks do have a pretty large fan on their twins. Maybe they do cool better with that large fan running at full throttle under no load. It's just my view that a engine running wide open is getting hot whether under load or not. More RPM, faster moving parts....more heat.

As far as the D series manual, it sounds like its describing to homeowners how to turn the engine off and not explaining a actual cooling procedure. Not nessisarily wrong buck lacking specific information that's addressed in more expensive models??
 

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For what it's worth...

My air cooled RX75 manual says: Stopping Engine

1. Move throttle lever fully rearward.
2. Let engine idle 15-30 seconds.
3. Turn key to OFF position.

And my liquid cooled LX178 manual says: Stopping Engine

1. Pull throttle lever down to slow position. Let engine idle before you stop it.
2. Turn key to OFF position.

ALSO in the manual...under troubleshooting - The solution to correct backfires is to replace the spark plug.
 

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Hmmmm, What's a air cooled engine.........LOL:bananapow
 

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Discussion Starter #19
For what it's worth...

My air cooled RX75 manual says: Stopping Engine

1. Move throttle lever fully rearward.
2. Let engine idle 15-30 seconds.
3. Turn key to OFF position.

And my liquid cooled LX178 manual says: Stopping Engine

1. Pull throttle lever down to slow position. Let engine idle before you stop it.
2. Turn key to OFF position.

ALSO in the manual...under troubleshooting - The solution to correct backfires is to replace the spark plug.
Replace the spark plug ??? If the backfiring is during shutdown while the key is OFF where does the spark plug come into play?

Fwiw I've never had a backfire in my machines. But my wife rode my X340 around awhile and just turned the engine right off. Guess what..backfire :fing20:
 

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I have two machines both with Kawasaki engines. The 345 is liquid cooled, and the X500 is air cooled. Here's what both manuals say;

345 shutdown;

2. Pull throttle lever (A) down to the slow position. Let engine reach low idle speed for a few seconds.
3. Turn key (B) to STOP position (C).

X500 shutdown;

2. Move throttle lever to half throttle position and allow engine to run at half throttle for several seconds.
3. Turn key to stop position.

So according to Deere, what is a few seconds and what is several seconds?. :dunno: I usually let them run for 30 seconds or so with no load.
 
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