Overheating Air Cooled Engine

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So, while mowing the lawn the other night I got to wondering how you tell if an air cooled engine is overheating? Short of anything major happening (smoke, burnt smell, engine death) , are there any early warning signs? Just curious, because I've smelled my old push mower get hot before when I was doing some heavy duty mulching - but that's about all I can point to.
 
Mine started dieseling, it wouldn't shut off after spark was removed!

You should consider that if airflow gets blocked by a mouse nest or something (common!) under the fan cowl area, it might throw off LESS heat while retaining more and, ergo, overheating. Walking behind a mower and feeling the heat off its engine is fairly normal.
 
Of course, you can always use an infra-red optical thermometer on it. I find that for fairly accurate readings, the surface should be flat black.
 
It's a real good idea to remove the flywheel housing and clean out the stray clippings every few years... Also on most engines there is a metal shroud that that directs air down one side and under the engine, these often fill with debris(I'm referring to a vertical shaft model)... The result is the lower cylinder area where the exhaust valve is located will badly overheat...
 
If debris is allowed to build, over time you can have an overheat prob..
While removing the blower housing is easy to do simply blowing to mower off after ea use should be sufficient. Also make sure you keep the screen free of dirt and grass as this is where air come into the blower housing.

Use your handheld blower when your done with the yard or even the nozzle on your compressor line to simply blow off all the grass and dirt.. The mowers I see with a huge build up are generally from lazy peeps that just don't take care of their stuff.. 30 seconds or so with the blower is all that's needed and goes a long way in keeping the unit in good shape. This transfers to the deck as well.. Since most deck shells on cheap homeowner units are really thin grass and debris allowed to sit on the deck and rot will also rot holes in the shell and ruin your spindles..

Again sure makes that 30-45 sec of time using the blower seem worth while to me..
 
Originally Posted By: TWG1572
So, while mowing the lawn the other night I got to wondering how you tell if an air cooled engine is overheating? Short of anything major happening (smoke, burnt smell, engine death) , are there any early warning signs? Just curious, because I've smelled my old push mower get hot before when I was doing some heavy duty mulching - but that's about all I can point to.



I am waiting for a 208cc snowblower to come in. While it is going to be used during winter, so it should be ok and not overheat.

I am more than likely going to use 5w30 Redline in it since it handles both cold starts and high heat stress so well. . . .

That and all the moly should keep wear down to a minimum. . . .
 
A friend of mine when I was a teenager had a Murray. He took the hood off,and the housing on the motor off,and used to mow like that. I told him he was going to fry that motor running it like that. He didnt seem to care,and the friggin thing ran a long time like that?
 
Originally Posted By: FNFAL308
If debris is allowed to build, over time you can have an overheat prob..
While removing the blower housing is easy to do simply blowing to mower off after ea use should be sufficient. Also make sure you keep the screen free of dirt and grass as this is where air come into the blower housing.

Use your handheld blower when your done with the yard or even the nozzle on your compressor line to simply blow off all the grass and dirt.. The mowers I see with a huge build up are generally from lazy peeps that just don't take care of their stuff.. 30 seconds or so with the blower is all that's needed and goes a long way in keeping the unit in good shape. This transfers to the deck as well.. Since most deck shells on cheap homeowner units are really thin grass and debris allowed to sit on the deck and rot will also rot holes in the shell and ruin your spindles..

Again sure makes that 30-45 sec of time using the blower seem worth while to me..


I can see how wet grass allowed to build up will rust the deck, but unsure how it will ruin the spindle. The spindle is not flush with the deck but part is raised. They are also made out of white metal I believe.
 
My neighbor always runs his mower with the hood removed. But not the engine cover.

I always open the hood on my Craftsman when I stop for a break.
 
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Originally Posted By: rg200amp
Originally Posted By: TWG1572
So, while mowing the lawn the other night I got to wondering how you tell if an air cooled engine is overheating? Short of anything major happening (smoke, burnt smell, engine death) , are there any early warning signs? Just curious, because I've smelled my old push mower get hot before when I was doing some heavy duty mulching - but that's about all I can point to.



I am waiting for a 208cc snowblower to come in. While it is going to be used during winter, so it should be ok and not overheat.

I am more than likely going to use 5w30 Redline in it since it handles both cold starts and high heat stress so well. . . .


?

That and all the moly should keep wear down to a minimum. . . .
\\





Help me out here---what in this post has anything to do with the thread
 
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Help me out here---what in this post has anything to do with the thread [/quote]



If the engine overheats, it will melt the snow!

How could you have possibly overlooked that?
33.gif
 
Originally Posted By: Donald
Originally Posted By: FNFAL308
If debris is allowed to build, over time you can have an overheat prob..
While removing the blower housing is easy to do simply blowing to mower off after ea use should be sufficient. Also make sure you keep the screen free of dirt and grass as this is where air come into the blower housing.

Use your handheld blower when your done with the yard or even the nozzle on your compressor line to simply blow off all the grass and dirt.. The mowers I see with a huge build up are generally from lazy peeps that just don't take care of their stuff.. 30 seconds or so with the blower is all that's needed and goes a long way in keeping the unit in good shape. This transfers to the deck as well.. Since most deck shells on cheap homeowner units are really thin grass and debris allowed to sit on the deck and rot will also rot holes in the shell and ruin your spindles..

Again sure makes that 30-45 sec of time using the blower seem worth while to me..


I can see how wet grass allowed to build up will rust the deck, but unsure how it will ruin the spindle. The spindle is not flush with the deck but part is raised. They are also made out of white metal I believe.


I think you may have misunderstood my comments, or taken them in a litteral sense? Maybe I should/could have been mor clear?

The Spindle housing itself does not fail from the grass, it ruins the bearings and in essence the spindle.. The spindle is on a number of units almost flush with the deck so it's quite possibe for the bearings to be covered in that nasty old rotten grass. The spinlde drive pulley is of course ellevated above that as it sits on the spindls shaft. Old nasty rotting grass is also not good for the belts..
 
Originally Posted By: steve20
when the muffler starts glowing red-you are about to either burn a valve or throw a rod---roll the dice............


A glowing muffler likely indicates a lean fuel mixture and could cause a burned valve, as far as throwing the rod, maybe but not probable...
 
Originally Posted By: TFB1
Originally Posted By: steve20
when the muffler starts glowing red-you are about to either burn a valve or throw a rod---roll the dice............


A glowing muffler likely indicates a lean fuel mixture and could cause a burned valve, as far as throwing the rod, maybe but not probable...


Not sure about glowing mufflers however, I've seen header pipes on all kinds of engines glow red in the dark with no observable ill effects.
 
Originally Posted By: boraticus
Originally Posted By: TFB1
Originally Posted By: steve20
when the muffler starts glowing red-you are about to either burn a valve or throw a rod---roll the dice............


A glowing muffler likely indicates a lean fuel mixture and could cause a burned valve, as far as throwing the rod, maybe but not probable...


Not sure about glowing mufflers however, I've seen header pipes on all kinds of engines glow red in the dark with no observable ill effects.


YUP, I have as well.. Actually pretty cool to see..
wink.gif
 
My Honda self propelled is 22 years old and I have a large lawn to mow. I use Mobil 1 oil in the engine and after each mowing I use compressed air to clean out the dust and grass around the engine.
 
Originally Posted By: FNFAL308
Originally Posted By: boraticus
Originally Posted By: TFB1
Originally Posted By: steve20
when the muffler starts glowing red-you are about to either burn a valve or throw a rod---roll the dice............


A glowing muffler likely indicates a lean fuel mixture and could cause a burned valve, as far as throwing the rod, maybe but not probable...


Not sure about glowing mufflers however, I've seen header pipes on all kinds of engines glow red in the dark with no observable ill effects.


YUP, I have as well.. Actually pretty cool to see..
wink.gif



Yeah a high HP engine can cherry the headers at WOT fairly quickly, also seen turbos that had a healthy glow after a hard run... Still I'd be a little worried about my mower if it's single digit horsepower engine were cherrying the muffler... Running at heavy throttle in tall grass could no doubt do so, but on average it should not happen...
 
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