This can't be right!

I installed a new muffler https://www.ebay.com/itm/Muffler-Allis-Chalmers-D15-70237811/123139319091?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649 on my gas D15 because my old one rusted out. It seem to work fine but while I was bush hogging the muffler got red hot!

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It burned the paint right off and if you look at that gray circle in the picture, that's where it got so hot.

What do you all think?

Looks pretty normal to me.  Red hot at night??... absolutely if the engine is worked hard enough.  Late ignition timing makes exhaust hotter than normal.

looks like a normal muffler coloring to me, bush hogging will make the engine run hotter, and all new mufflers lose their paint after start up. discoloration is also normal on them. you can re-paint it with high temp spray paint after each use if you want it to look nice!

Agree with everyone, My dad ran a WD on an irrigation pump and at night under full load the manifold and exhaust pipe were cherry red. Our local mechanic who overhaul the tractor didn't believe it until he came out one night to see for himself.

Dad opened the carb some when puling combine with pto.Late in even it was almost a flame coming out of exhaust.Exhaust on W C was a plain 8 in pipe flat on end.That was factory.Later dad had to wear hearing aids.

haft to knock that plug out of the center of the muffler. it will run cooler an breath better let's the ex; out' not hold it back' take a long punch an knock it out' looks like a freeze plug.

Running a bit rich gets more power out of a piston engine. I used to run my MF-135 a bit rich for faster plowing. Rich enough to show a bit of black smoke in the exhaust. Didn't cause the manifold or muffler to glow.

Its been standard practice in piston aircraft engines to run rich for take off to produce the maximum power then when at cruising altitude to lean the mixture until the exhaust temperature rises about 500 degrees Fahrenheit. The fuel flow gauge often shows fuel consumption down by a factor of at least 5. ON aircraft I have hired for charters there was an exhaust gas temperature gauge and some had a fuel flow gauge and all had a mixture adjustment on the dash panel.

My Onan 5 KW generator with a Continental Y-91 engine (way oversize for the load to allow burning poor quality coal gas) running on gasoline drank a couple gallons of gasoline an hour even when lightly loaded. The gasoline main jet in the combination fuel carburetor wasn't adjustable. I made an adjustable needle for the jet and raised the exhaust temperature about 300 degrees F and cut the gasoline consumption down to half a gallon an hour even when loaded pretty heavily.

Ignition timing late can contribute to hot exhaust too. Glowing exhaust parts might be a hint to dig in to the distributor and to make the centrifugal advance go back to work. The mechanism has been known to fail from rust or broken springs or advance weights. Typically that mechanism needs a few drops of oil down the hollow distributor shaft with the rotor removed a couple times a year.

Gerald J.