Max engine temp

[Maxwell-8 4,275]

What is a safe maximum engine temperature of an air cooled engine like a kohler or chainsaw?

They seem to run twice as hot as an liquid cooled engine. 

[ebinmaine 67,498]

Seems to me there's a lot of variability in that answer.

I should think a Kohler under load is going to be substantially hotter than one at no load. 

 

It would also be important to consider the RPM given the fact that the flywheel fan would not be moving as fast at lower RPMs. 

 

I don't know enough about chainsaws or two-cycle engines in general to answer if they would be hotter or colder than a standard 4 cycle engine.

 

@Greentored I think it was you that was involved in a discussion about air-cooled temperatures at one point?

 

[gwest_ca-(File Mod) 11,045]

This is an Onan part

[Maxwell-8 4,275]

I got me some hot-runners then.  (Maybe to lean)

[ebinmaine 67,498]

50 minutes ago, Maxwell-8 said:

I got me some hot-runners then.  (Maybe to lean)

Make sure you're measuring them in the correct place

[ebinmaine 67,498]

1 hour ago, Maxwell-8 said:

I got me some hot-runners then.  (Maybe to lean)

I'm curious to know where on the engine you're measuring? With what tool? And what are your readings?

 

 

[pacer 3,169]

38 minutes ago, ebinmaine said:

where on the engine you're measuring? With what tool? And what are your readings?

 

 

Good question --- obviously the surrounding area around the head would be the heat area, with maybe a higher reading around the exhaust and a bit less around intake (cooler fuel going in, heated air going out??) course I suppose the area around the plug would be pretty hot also ,,,,,but? youve got the tins covering a lot of this area.... Hmmmmm, vedy interesting! Would think one of the laser temp guns would be handy for this.

[Maxwell-8 4,275]

2 hours ago, pacer said:

Would think one of the laser temp guns would be handy for this.

That's what i am using, and found out the hottest place is on the head on the exhaust-side . 

3 hours ago, ebinmaine said:

And what are your readings?

Gettting readings of 400° on a 4 stroke chinese piece of junk

[ebinmaine 67,498]

8 minutes ago, Maxwell-8 said:

That's what i am using, and found out the hottest place is on the head on the exhaust-side . 

Gettting readings of 400° on a 4 stroke chinese piece of junk

That sounds like it's high but if it's right near the exhaust pipe that might not be out of spec. 

[pacer 3,169]

For instance, where is this 'temperature switch' placed?? would get different readings in several places. I would think that 400° at the exhaust wouldnt be unusual.  For example, have you ever seen the exhaust pipe at the exit of the block glowing a bright cherry red?? At high rpms its very common.

[Handy Don 12,231]

20 minutes ago, Maxwell-8 said:

That's what i am using, and found out the hottest place is on the head on the exhaust-side . 

Gettting readings of 400° on a 4 stroke chinese piece of junk

The temp sensor on the Onan P220 is on the right side on the forward cylinder down near the starter solenoid. My 218 doesn't have one. This is away from the valves and manifolds, which are on top, and where the cooling airflow is exiting past the fins. It is attached in a boss cast into a cooling fine with metal contact.

 

Now you've put an idea into my head and next time I'm running the 218 I'm gonna bring the infrared "gun" that I use for checking on my wood stove.

 

BTW, on a clear day aim one of these at the sky and you'll often see -40º (C and F are the same at this temp)--nothing up there emitting or reflecting infrared!

[WheelHorse520H 708]

6 hours ago, Handy Don said:

BTW, on a clear day aim one of these at the sky and you'll often see -40º (C and F are the same at this temp)--nothing up there emitting or reflecting infrared!

Seems like you got bored! Although that sounds like something I would do, sooo.

 

6 hours ago, Handy Don said:

The temp sensor on the Onan P220 is on the right side on the forward cylinder down near the starter solenoid.

That’s correct, in the attached photo you can see the base of the dipstick tube, it is like 2 inches above that, that’s where I would measure.

[Greentored 3,211]

23 hours ago, ebinmaine said:

 

 

@Greentored I think it was you that was involved in a discussion about air-cooled temperatures at one point?

 

Yes sir, somewhere here in the archives.

Not sure what a 'correct' temp should be, but back in the kart days the Briggs would see WELL into the upper 400s under race conditions, taken at the spark plug. 

Think about Harleys- they rely on cooling air while in motion- no fans whatsoever on 99.9% of them, and can COOK in heavy traffic situations, yet rarely an issue.

They also rely on the oil to keep things under control, and oil temps can often hit 200+ pretty quick.

What all this boils down to is- head temps don't seem to matter much, but if you cook your oil, you cook the bottom end, right?

For this reason, I put an oil temp gauge on Hoss and monitor that instead. With a well built K321 at 9.3:1 under heavy work, I have not seen oil temps over 140ish yet.  Summer is coming and that may be a different story.

[WheelHorse520H 708]

5 hours ago, Greentored said:

What all this boils down to is- head temps

Forgot to mention, the sensor is called the cylinder head temperature sensor.

[Manuel 8]

Has any of you installed an exhaust temperature gauge in your tractor? I have an onan p220 in a 520h WH I bought in 98 and thinking it may not be a bad idea to do. I appreciate any suggestions and/or your thought on this. Thanks

[ebinmaine 67,498]

9 hours ago, Manuel said:

Has any of you installed an exhaust temperature gauge in your tractor? I have an onan p220 in a 520h WH I bought in 98 and thinking it may not be a bad idea to do. I appreciate any suggestions and/or your thought on this. Thanks

 

Depends what you want to know. 

 

On a two cylinder I'd want TWO exhaust  sensors. One for each. Output temp would be nice to know but individual cylinder temps will vary, a lot. 

 

If you're looking to find the total engine temperature it might be better to follow @Greentored Scott's advice and install an OIL temp sensor.  

 

[Manuel 8]

Thank you very much Eric

[RED-Z06 2,221]

I run a head temp sensor on various engines, my K241 runs 204* wide open no load 45* ambient.  Mid summer at full governor it will hit 280*.