Why is my muffler glowing red hot.

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I was able to pick up a second hand small generator. It’s an old Coleman power mate. It has a five horse Briggs and Stratton engine I was surprised when it started right up.
I have two problems that I could see right off hand. (1) After about two minutes the muffler started glowing red hot. Also every now and then sparks fly out of it. It is located right above the gas tank and so I’m worried about that.
(2) The thing vibrates around so much but I don’t think that there is too much to do about that.
Any suggestions?
Is it running too rich? Should I get a new muffler?
 
You need to get the carburetor adjusted, if it is vibrating then the mixture is probably wrong.

You may have to take the carburetor off and clean it.
 
late ignition timing will also cause this. If the engine has a flywheel magneto, the key may have sheared off, allowing the flywheel to shift out of register.
 
Wow. Thanks.
Do you think I should just take it to a fix it shop or break out a small engine repair book and work on it myself?
They might be able to fix it in a short time or less while it might take me a few hours.
 
Originally Posted By: handyman
Wow. Thanks.
Do you think I should just take it to a fix it shop or break out a small engine repair book and work on it myself?
They might be able to fix it in a short time or less while it might take me a few hours.



I guess it depends how mechanically inclined you are.

I have cleaned small carbs and adjusted them, that's easy, just do not know about the flywheel key. Maybe someone else on here can walk you through that.
 
Hot = lean but late timing is also suspect.

I imagine the carb is pretty dirty, and the jet is not clear enough to provide the full amount of fuel. You won't be able to clean this with additives, you'll probably need to get into the carb. At least remove the bowl and get a feel for how much varnish there is.

The shroud is easy enough to remove, and you can see if the keyhole matches or not for flywheel timing.
 
You also might was to check the muffler to see if it has a spark arrester screen in it. Sometimes they can get plugged up which causes excess heat to build up in the muffler and it's not letting the exhaust escape like it should. This would also cause sparks and ruff idling.
 
[1] your carb is too LEAN open the screw on the bottom of the carb 1/8 of a turn ..

[2]to get at the flywheel key you will have to remove the nut on top of the flywheel ,than u can see if the flywheel key slot is in line with the crankshaft key slot..if they're not in line u need a puller to remove the flywheel and replace the key...
 
I would run it without muffler for more than the 2 min. and see if problems still occur, if not new muffler may be the fix. Leanness and late timing are also possible. More likely maintanence issue dirty carb, over carboned head/piston/valves, or junk in gas tank.
 
Anything it possible but a sheared flywheel key on a generator would be way down on my list. I'd quick-check the muffler then valve clearances and junp on the carb.
 
I wonder if he has a clogged muffler, kind of like a cat-converter getting hot or glowing when it is hot, just a thought.
 
Yep, on somehting like a 5hp, it's either leaning out for some reason, or it's reving above the RPMs it was originally governed to. As far as vibs? Any flat head single cyl powered generator I've ever seen will shake itself to pieces. I've got a ~6yr/old Coleman Powermate suitcase style 1800 Watt job. It's got a HUGE muffler on it that makes it quiet for an old school Briggs 3.5hp, but even with the rubber isolators, screws loosen and panels fall right off if it's run for hours on end.

Joel
 
Run some premium. Premium resists lean conditions a little better. If that doesn't help, do any and everything above.
 
So.............how is running lean going to create excess heat in the exhaust? Check for loose flywheel/partially sheared key. Sometimes a partially sheared key is tough to spot.
 
Combustion/cylinder temp goes way up when leaned out = hot exhaust. It could very well be the ingition timing is off due to a buggered key, just seems unlikely being only a 5hp in generator service. The only way to really *jar* the output shaft and/or flywheel & distort the key would be a massive backfire. If it was running rich it would be puffing black smoke and running like p00p.

Joel
 
Originally Posted By: punisher
So.............how is running lean going to create excess heat in the exhaust?

Aircraft give you the ability to adjust the fuel trim (A/F Ratio) while in flight. Leaning things out will increase fuel economy, but increase the EGT (Exhaust Gas Temperatures). If not kept in check, the engine will begin to overheat and could possibly fail, which is not a good thing while flying.

I'm not here to tell you why, but I am here to tell you with ABSOLUTE CERTAINTY that running lean increases the temperature of your exhaust. I'm sure the 7 people in this thread that said to check the carb because of a possible lean condition aren't total insane.
 
It's the new normal. Many new small engines do this. My Honda 13HP pressure washer does it, my old Briggs 6.5HP pressure washer does it. Most new 4 stroke dirt bikes also get the pipe red hot.

Chris
 
well,i remember when i was a kid,my father and i belonged to a hunting club.it was just a few guy`s from his work.anyway,we had this cabin up in long pond,pa and we used an 8hp b&s generator.after a few hours of running,that muffler got cherry red as well.this dates back to around 1977 or so.
 
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