# Muffler glowing red



## GoBlowSnow (Sep 4, 2015)

Hi Gang- 

Need some advice from the experts. Tecumseh 8 HP engine early 90s vintage. (not mine) when I was doing some fine tuning of the carb earlier this year, I could see the muffler start to glow red, but with a few changes to the carb adjustment it would go away. I ended up rebuilding the carb recently and the machine runs much better, but have not yet ran it at night to see if it gets the muffler hot enough to start glowing. 

Thoughts on why it would glow in the first place? Just the mixture not being set correctly? The muffler seems to be in good shape otherwise and the machine is stored inside a shed and has been since they purchased it. Gasoline is always fresh and the fuel shut off is always turned off after done with the snow blowing, allowing the engine to die once it's used up all the fuel in the line and carb.


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## Normex (Feb 21, 2014)

GoBlowSnow said:


> Hi Gang-
> Thoughts on why it would glow in the first place? Just the mixture not being set correctly?


 When the muffler glows it means it is running lean but a little glowing in the dark is no cause for alarm. So if you can adjust it so it doesn't glow just don't go to the rich side too much where you will gum up the spark plug hence having hard starts.


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## tdipaul (Jul 11, 2015)

If the machine has been in a shed for any amount of time it might be worth verifying that there isn't mouse nest under the flywheel shroud. 

A nest would restrict cooling air and cause the engine to run hot.


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## CO Snow (Dec 8, 2011)

Take the muffler off and check it. Mine did that and it had rusted internally and had a loose part that you could hear when shaken. You may also have a bad gasket.


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## micah68kj (Oct 8, 2011)

Normex said:


> When the muffler glows it means it is running lean but a little glowing in the dark is no cause for alarm. So if you can adjust it so it doesn't glow just don't go to the rich side too much where you will gum up the spark plug hence having hard starts.


+1 on this


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## UNDERTAKER (Dec 30, 2013)

Are the revs per minute within specs??????????????????????


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## Grunt (Nov 11, 2013)

GoBlowSnow said:


> when I was doing some fine tuning of the carb earlier this year


 Don't forget, these are air cooled motors with extra shielding designed to be run in colder temperatures. Tuning a snow engine when it is 80 or 90 degrees out will have some effect on the engine and I agree with Norms assessment.


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## GoBlowSnow (Sep 4, 2015)

Thanks for the input. I will pull the muffler this weekend and have a look. I will also give a good look around for any signs of a nest. 

Regarding the tuning of the engine, very good point there too, thank you. It was running very nicely when I gave her a little trial run Wednesday morning after we got a few inches of snow Tuesday night into Wednesday. 

PowerShift- you asked: Are the revs per minute within specs??????????????????????

I would not be surprised if they are not within spec. Having never done this before, what would be the best way of checking the revs? I can certainly look up what the specs would be online for that year/model, but not sure how to check the revs? Never done that before.

thank you!


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## Normex (Feb 21, 2014)

GoBlowSnow said:


> I would not be surprised if they are not within spec. Having never done this before, what would be the best way of checking the revs? I can certainly look up what the specs would be online for that year/model, but not sure how to check the revs? Never done that before.


 Here's a few that you can purchase. Normally a snow blower rpm when at full throttle is 3,600 rpm.
Good Luck
Small Engine Tachometer | eBay


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## 43128 (Feb 14, 2014)

could also be an exhaust valve issue


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## YSHSfan (Jun 25, 2014)

GoBlowSnow said:


> Hi Gang-
> 
> Need some advice from the experts. Tecumseh 8 HP engine early 90s vintage. (not mine) when I was doing some fine tuning of the carb earlier this year, I could see the muffler start to glow red, but with a few changes to the carb adjustment it would go away. I ended up rebuilding the carb recently and the machine runs much better, but have not yet ran it at night to see if it gets the muffler hot enough to start glowing.
> 
> Thoughts on why it would glow in the first place? Just the mixture not being set correctly? The muffler seems to be in good shape otherwise and the machine is stored inside a shed and has been since they purchased it. Gasoline is always fresh and the fuel shut off is always turned off after done with the snow blowing, allowing the engine to die once it's used up all the fuel in the line and carb.


I had the muffler get red hot on one of my predator engines. My thought was that it was running too rich (I had rejet it from believe .72mm to .89 or .92mm), also you could see the engine spiting small flames thru the muffler. I replaced the .72mm jet back it and it took care of the issue. Just my experience.....


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## CarlB (Jan 2, 2011)

hsblowersfan said:


> I had the muffler get red hot on one of my predator engines. My thought was that it was running too rich (I had rejet it from believe .72mm to .89 or .92mm), also you could see the engine spiting small flames thru the muffler. I replaced the .72mm jet back it and it took care of the issue. Just my experience.....


Thats a big jump from .72 to .92mm on the jet. I suspect what was happening was that it was so rich that the unburnt fuel was igniting in the hot muffler and making it glow red. Normally a glowing muffler is a sign of a lean engine.


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## bwright1818 (Dec 2, 2014)

Like everybody has said already, mixture is a big one. Also agree highly about a mouse nest! That being said, I never saw my snow machine mufflers glow red, probably because it was cold....but my 8 hp Tecumseh generator engine's muffler glows a soft red at speed, when seen at night....I think this is normal, although a bit disconcerting....


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## GoBlowSnow (Sep 4, 2015)

It was a soft red. Again thank you for the feedback and advice. Going to order a tach right now.


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