Minimum RPM for Kohler engine to "idle" at safely

[wallfish 17,201]

Out of all the engines that have gone through here over the years (and many are still here running perfectly fine), not one has ever popped because of idling too long. Even in the summer time. Probably set mine around 1500 ish RPM for idle speed.

I'm not sure they require as much of a splash lube cycle of oil at idle as they do at full throttle and or under load. IMO, a 1500 ish rpm dipper splash is still pretty violent in there and splashing enough oil around to lube it. The air volume is still enough to cool the head under those conditions if the fins are clear and not plugged up. What I wouldn't do is run them under load at lower RPMs. However, I have cruised around at many shows over the years at lower RPM because the exhaust is quieter with the same tractor and engine. Engine(s) are still plugging away many years later without any ill effects. Not much load on them through the gearing of the trans.

Has anyone here ever actually had a good engine blow up just from idling it too long?

 

[ebinmaine 69,743]

1 minute ago, wallfish said:

if the fins are clear and not plugged up.

 

 

That's very important!!!

 

 

 

[Ed Kennell 39,769]

Just my               I think we all agree we must run our tractors at WOT while they are under load...mowing, plowing, tilling, blowing snow, pulling , etc.

 

I also use my 312H for hauling in firewood in the winter and I too find condensation in the oil fill tube.  This is due to the many short runs that never allow the engine to got warm enough to drive off the moisture.     BTW, this tractor is stored in a 60F heated garage

To help prevent this condition, I let my tractor run for longer time periods including letting it run at fast idle (about 1500) while loading and unloading. 

I neve had any indication it is lacking for lubrication.

 

My guess is the only time the dipper lubed engines blow is when they are parked on a slope and left to idle till they die.

Edited Thursday at 04:42 PM by Ed Kennell

[JCM 9,928]

1 hour ago, wallfish said:

Out of all the engines that have gone through here over the years (and many are still here running perfectly fine), not one has ever popped because of idling too long. Even in the summer time. Probably set mine around 1500 ish RPM for idle speed.

I'm not sure they require as much of a splash lube cycle of oil at idle as they do at full throttle and or under load. IMO, a 1500 ish rpm dipper splash is still pretty violent in there and splashing enough oil around to lube it. The air volume is still enough to cool the head under those conditions if the fins are clear and not plugged up. What I wouldn't do is run them under load at lower RPMs. However, I have cruised around at many shows over the years at lower RPM because the exhaust is quieter with the same tractor and engine. Engine(s) are still plugging away many years later without any ill effects. Not much load on them through the gearing of the trans.

Has anyone here ever actually had a good engine blow up just from idling it too long?

 

  All mine have idled as much as they have run at 3/4 throttle, so far no issues.Idle them down for a few minutes before shutting them off. Oil change every 25 hours. Only one ever run at full throttle is the 520-H with the 44'' 2 stage when needed in heavy wet snow. Been running them this way since my 312-8 in 1989 when new.     

[squonk 41,942]

I almost never run at WOT. And I idle close to 900. Been doing it forever. Never blown up a Kohler. The only engine I have had trouble with personally was already worn out when I got it. We blew up Teckys back in the 60's and 70's trying to push feet of snow and mowing multiple acres of grass with a little 6 banger. I think the biggest thing is not changing the oil and using Non Detergent oil and not getting the crap flushed out. 

[RED-Z06 2,390]

Always love data.  I took my C100 out just now, it has a CHT gauge on it, it normally runs 270⁰-280⁰ mowing in the summer, but the ambient today was 50⁰, i fired it up, checked idle speed which was 1206rpm, and set low idle for 16 minutes, the temperature had stabilized at 195⁰-197⁰ for a few minutes, thats well under any kind of dangerous temperature.

 

 

 

[MainelyWheelhorse 768]

On 2/19/2025 at 2:32 PM, Ed Kennell said:

Probably not.    Some still use clutches, stick shifts, and blowers w/o cabs.  

 

On 2/19/2025 at 2:33 PM, ebinmaine said:

 

 

You modern guys with your fully enclosed People Protection Systems...

 

 

Do plows with no cab count??? I do layer up at least three times though...

[Racinbob 11,463]

I set the idle by what sounds good and ride around a lot at low RPM. There's still a lot of airflow and plenty of splishy splashy as that dipper hits the oil so many times a second. It's never caused me an issue in over 6 decades. Of course most PTO driven attachments should be full throttle Not a sickle bar though. I'll use it several hours at a time with the throttle just above idle. 

[ebinmaine 69,743]

2 hours ago, Racinbob said:

Not a sickle bar though

 

 

I was waiting for someone to bring that up. I thought of it as soon as I saw the initial post. I figured I would let someone else toss That Monkey Wrench in the works.

 

 

[Racinbob 11,463]

I guess I'm the monkey wrench king these days. I'm not saying they're wrong about the RPM. Could be something to it. I'm just saying I've never had an issue idling down an engine even for extended periods so I figure that's one thing this old dog doesn't need to learn.

Now the talk about cabs for blowing snow? I'm a wimp. There's no such thing as downwind when blowing snow. I'd definitely grab one if it called my name. 

[MainelyWheelhorse 768]

I’m not sure of the rpm of what I set both of mine on. I set mine by the task and load. I usually go by ear, and set it high enough to not bog under a load, like pushing snow, or dragging a tow behind leaf rake. But not wide open for long periods unless it calls for it. The stuff like running a mowing deck or something that needs to be spun at a high rpm etc….I’ve had my 312 for 3 years with no issues.