Muffler glowing red?

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So I'm going to start by saying I know nothing about small engines or carburetors or anything having to do with this section. And I'm kind of embarrassed by my lack of knowledge but I need to ask... I have a Yard Man snowblower, one of the big ones on tracks instead of wheels. I have two issues. First - after running for a while, it looses it's "go". Like it slows down and won't move as fast. Sometimes it will quit moving altogether (the engine runs, it just won't move). From looking at the parts diagram I see there's a friction disk part. I'm guessing replacing the rubber there would be my first step in trying to fix this? Anything else to look at? Second - this is the dumb one. My muffler glows red hot sometimes. I'm guessing this isn't normal? blush So when this happens, I can get it cooled down by closing the throttle a bit. But, obviously I'd rather get it fixed right. This would be a carb issue? Is it running lean? Is it worth trying to run some carb cleaner through the fuel, or should I start with taking the carb off and trying to clean stuff? I have no idea what I'm doing so I was thinking about taking it apart, hosing everything down with carb cleaner, and re-assembling. My engine is a Tecumseh HMSK90 - I Google "HMSK90 carb rebuild kit" but all I get are replacement carbs. I couldn't find a rebuild kit listed as a part looking at genuine Tecumseh parts dealers, either. Does this mean there's not such thing, or am I mis-Googling here? Thanks for any help!
 
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First, you may need to replace your drive disk and/or belts. I'm going to guess you never have. Check the cable tension, replace the belts, and if needed, replace the drive disk. You're running lean and causing the muffler to glow red hot. If the carb is adjustable, it needs to be richened up a bit. Start at 1/8 or 1/4 turn. If it starts easily and runs properly, there shouldn't be a need to rebuild/replace the carb unless it lacks the adjustment screw at the base of the carburetor bowl. You may only need to clean the bottom jet (the one holding the bowl) to get it running correctly again. Get your carb spray and a stripped twist tie and clean all the little holes (especially the center one). Most Tecumsehs I see don't need much more than cleaning the bottom jet and then running some good treated fuel (Amsoil, Sea Foam etc) through it to get the remaining varnish out.
 
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JTK

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It could be running lean at times if the muffler glows. If this old 9hp flat head engine starts easily, idles smooth and is fine under load, I'd leave the carb alone. In regards to the 'drive' issues, it could be a worn drive belt or or just needs the cable tension tightened on the motion control lever. I'd start by popping the belt guard off to inspect the belts. You can also take the belly pan off to inspect the friction disk. ** SORRY PHIL! you beat me to it.
 
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The glowing muffler, if not a carb running lean issue, may also be too little lash in the exhaust valve. This would keep the exhaust valve from closing completely during the combustion stroke and sending some of the burning fuel out the valve through the muffler where it finishes burning. donyboy73 has a good Youtube video on his channel showing this happening. If you're not familiar with Tecumsehs, adjusting the valve lash would be above your skill level.
 
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My dad's Kohler K301 (1973 Cub Cadet 129) had a glowing muffler shortly before it went boom. I got lucky and it just needed a new connecting rod - the crank and everything else was OK. I replaced the rod and the muffler started glowing again as soon as I started it after the repair. The carb wasn't lean - it turned out that the ignition timing was way off. I adjusted it by changing the breaker point gap on that model. It has been running fine ever since (about 14 years). If that Tecumseh has an ignition timing adjustment, I would make sure it is OK. Air cooled engines to not tolerate incorrect ignition timing very well. Andrew S.
 
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Maybe apples and oranges. I blew up 2 mufflers and melted the ceramic matrix in a Jeep with a a 360 V8. It ran but not great. The cat was incandescent after 10 minutes. The problem was a weak coil. Check /change the oil. Just 'cuz. The ball park adjustment for most carbs is to run the main jet or idle mixture screw in until it snugs. Then back it out 1 and 1/2 turns. Timing could affect it for sure. So does a mouse nest, or grass clippings in the cooling fins. Last summer, I cleaned 40 yrs of crud off the hydro's case. That is all I did. I have new drive belts waiting to be put in. The Inty Cadet 80 sitdown mower mows the bulk of the yard. For the last few seasons,it has been whining under load when warm. All I did was clean it off and I swear the whine is gone.
 
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Originally Posted By: threeputtpar
The glowing muffler, if not a carb running lean issue, may also be too little lash in the exhaust valve. This would keep the exhaust valve from closing completely during the combustion stroke and sending some of the burning fuel out the valve through the muffler where it finishes burning. donyboy73 has a good Youtube video on his channel showing this happening. If you're not familiar with Tecumsehs, adjusting the valve lash would be above your skill level.
That is a possibility. You will clearly see flames shooting out of the muffler if that is the case. Nothing like taking a belt sander to the valve stem to remove 1000ths/in.
 

Smcatub

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Thanks for the advice. I haven't gotten around to checking anything out yet - it's been either too dark or too cold. I suppose I'll have to take a look this weekend, and get things done before we get the next storm.
 
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The muffler glowing red at full throttle (visible at night) is normal. If the engine is running good, don't worry about it. If it is running lean, it won't run right and it will lack power.
 
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I had a old generator that would glow the muffler red [ at night] . Ran MANY a hour like that . May have been lean . IDK . Was always terrible to start cold so probably was some what lean .
 

Smcatub

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Ok, so I took the time to do some work on this thing over the weekend. I pulled the carb off and had no idea what I was doing. I took it apart as best I could. Soaked the main jet in a cup of degreaser. Then cleaned the holes with a wire. Then soaked in a shotglass full of carb cleaner. I soaked the body of the carb in a solution of degreaser, rinsed in water, then ran some iso alcohol through to help dry it. After struggling with remembering how the throttle linkage went, I got in re-installed (with a new gasket, just in case). I took off the bottom cover to take a look at the cables and found the problem - my drive plate was covered in oil, probably from me being clumsy when doing my last change. After some time with the degreaser I managed to get the drive plate and the rubber disc cleaned off. Adjusted the drive cable as best as I could figure out while I had it open (the rubber friction disc has about 1/8th clearance while not engaged, but is firmly pressed into the drive disk when I hit the drive lever). I started it up - it pull starts way easier now, and goes fine when I hit the drive lever. I didn't run it long, but longer than it took for the muffler to glow red last time, and so far no glow. Hopefully all will be well when the snow flies! The only bad thing is I lost the plastic knob for the choke somewhere along the way, so not I have to adjust the choke with pliars It is loud as heck though. I did a new muffler last year which didn't help. I'd like to quiet the exhaust but I'm not sure how. Something to look into I guess.
 

JTK

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Good work Smc! I don't think there's much you can do in regards to noise. To me, 8hp and above Tecumseh Snow Techs (flat head versions) are LOUD. You gotta hear the 11hp one we keep at my mom's. Earplug city.
 
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Does this muffler use a gasket? Dad's old John Deere blower had a 10hp Tecumseh or a Kohler that used a gasket. Was much quieter with the gasket in place ... but I don't believe the one I put in there lasted long. It was made of a sintered material ... really dirty, almost like lead.
 

Smcatub

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There was not a gasket in place when I removed the old muffler. Maybe that was the problem in the first place? I'll have to check out a parts diagram and see what there is to see. Good idea, thanks
 

Smcatub

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Today it got it's first test since I cleaned the carb. It blew the rod through the side of the engine block frown I'm not sure what to do at this point. Get a new engine or put the machine up on Craigslist. Can't really afford the $550 or so new ones are going for now but I don't want to put a bunch of money and work into an old machine. Oh well....
 
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Or find a clean used one off Craigslist. You can find the better brands like John Deere, Ariens, Simplicity. Just check over carefully and make sure to run it for a while before laying out any cash. don't want to buy someone else's problem.
 

Smcatub

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Originally Posted By: cronk
Another option is to repower with a Harbor Freight engine. Although, if the engine was a dual shaft unit, that would not be practical.
I'm going to look into this. Is there a cross-reference available somewhere, or do I just have to go by the crankshaft / other dimensions to figure out if it'll fit? If I could get a new engine at a good price I'd be happy with that
 
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