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Discussion Starter #1 (Edited)
Hello to all. I'm new to the forum. I found this place doing a search on Tecumseh engines. Sorry for long explanation, but, I just want to be thorough.
Some basic info: (North Star - from Northern Tool) Murray 629118X0A Bought new in 2003. I'm the original owner. Been using ethanol free fuel and stabilizer for the last 10 years. All basic maintenance was done by me. Engine would fire-up 1-2 pulls with a few pushes on the primer and full choke. I've only used the e start a few times. Machine has functioned, and ran flawlessly for all these years. Never a blower or engine problems until now. Blower sits in my climate controlled garage all year except for when I need to clear snow. I replace the oil (5W-30 synthetic) and drain the fuel after the season is over.
Here's what has happened. Two weeks ago was the first time the blower needed to be used. I checked my oil level and filled the tank with fresh non ethanol fuel. Didn't start on a few pulls after doing what I've been doing since day one. I then went to the e start. It fired-up after 4 or so attempts. Idled fine for a minute or two. Went to raise the throttle and that's when I heard a loud rapping noise coming from the engine. ( I've never heard anything like this ever from this engine. I shut it down immediately. I don't have a compression tester, but, I pulled the spark plug wire off and pulled the cord several times. I had the normal amount of compression when pulling as I remember.
A few days later I pulled the head for inspection. Some carbon on the cylinder and valves. I then pulled the engine off the machine and tore it down. I'm no expert when it comes to engines. This is my first tear-down. I just like to tinker. The piston, rings, connecting rod, valves and clearance, crank, and cam look good to me. The cylinder wall still has cross hatch marks with no scoring.
Could it have been a carbon build-up on the piston that caused this horrendous sound ? Any help would be greatly appreciated. Thanks








 

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welcome!

that's pretty typical carbon build-up for an engine this age.

good on you for jumping right in!

Unless it ingested something (you'd see ding marks on the head/piston), it could it be a fuel issue; super-rich (choked?) or super-lean (dirty carb?). was it coughing-up a bunch of black smoke when it was making all of that racket?

what did the spark plug look like?

Lastly, are you positive the noise was coming from the engine and not the machine itself?
 

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Does your machine have a light on it? Possibly a magnet came loose from the inside of the flywheel?

Welcome to SBF.
 
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Discussion Starter #5 (Edited)
welcome!

that's pretty typical carbon build-up for an engine this age.

good on you for jumping right in!

Unless it ingested something (you'd see ding marks on the head/piston), it could it be a fuel issue; super-rich (choked?) or super-lean (dirty carb?). was it coughing-up a bunch of black smoke when it was making all of that racket?

what did the spark plug look like?

Lastly, are you positive the noise was coming from the engine and not the machine itself?
Thanks for the welcome and response. I appreciate it. I figured, what the heck. I'm not going to run it like this. No ding marks on the head or piston. Once it started, I took the choke off like normal. The noise came when I increased the throttle. No coughing or black smoke at all. Spark plug has some dry carbon build-up on it, but nothing too bad or wet.

Yes, I'm positive it was from the engine. After I pulled the engine off the blower, I took the bottom pan off and check the entire drive-line. All is good and tight. I then went through rest of the blower pushing and pulling on all parts. Auger and impeller are fine. Discharge chute is fastened properly, and tight. I even raised the unit off the ground and pulled and pushed both wheels. All is OK.
 

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Discussion Starter #6
Does your machine have a light on it? Possibly a magnet came loose from the inside of the flywheel?

Welcome to SBF.

Thanks for the welcome and response as well. I appreciate it. Yes it does have a light. That was one of the things I saw when I did a search. All 3 magnets are intact in the inside of the Flywheel. I also learned about the possibility of a busted Flywheel key. The key was intact, no cracks or broken pieces.
 

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Welcome, and good for you for just diving into the engine! I've worked on several machines, including some engine work, but haven't been brave enough to open up the bottom end. Of course, they haven't needed it, so there was no real reason to.

I'm having a hard time thinking of what in an engine would go from sounding normal, to a noise like that, as you raised the RPM.

I realize this is probably tough to answer, but how frequent was the noise, did it seem like it was with every engine revolution, for instance?

I'd probably put the engine back on the machine, but don't install any of the belts. Start the engine, and see if you hear the noise as you change the speed. If you don't, add the belts, and check again. On my Ariens, the transmission belt is turning constantly, even before squeezing the handle. So there is at least something else spinning along with the engine, as another possible source of noise. If yours is the same way, it may be worth doing the test, just to help confirm the source of the noise.

If you confirm it's the engine, great, ignore the other stuff. And if perchance the noise changes when you add a belt, then you can better focus your troubleshooting.

PS- If you have a mechanic's stethoscope (like this https://www.amazon.com/ABN-Mechanics-Stethoscope/dp/B01BUJZBOO/), you could use that to help pinpoint the noise location, by touching it to different areas with the engine running. Or you can use something like a rod, with one end against the engine, and the other end against your ear, or the side of your head. Just anything to help transmit noise directly from specific locations on the machine.
 

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Discussion Starter #8
Classic cat, I just realized you're in Albany. I'm in Jefferson, Schoharie County a few miles off of I-88
It's a small world !!!!!!! It's freezing up on the mountain for the last week plus. I know you guys are only 10 degrees warmer.
 

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brother grunt had a good suggestion...maybe something got slapped around the shroud / flywheel.

since it's still apart, inspect the governor spool closely to make sure that it did not grenade, lose a counterweight, some teeth, etc. It's plastic.

Inspect the cam closely...specifically at the compression release mechanism.

Have you taken the valve cover (breather) off to see if both valve keepers are still seated and the valve springs in place?
 

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Discussion Starter #10
Welcome, and good for you for just diving into the engine! I've worked on several machines, including some engine work, but haven't been brave enough to open up the bottom end. Of course, they haven't needed it, so there was no real reason to.

I'm having a hard time thinking of what in an engine would go from sounding normal, to a noise like that, as you raised the RPM.

I realize this is probably tough to answer, but how frequent was the noise, did it seem like it was with every engine revolution, for instance?

I'd probably put the engine back on the machine, but don't install any of the belts. Start the engine, and see if you hear the noise as you change the speed. If you don't, add the belts, and check again. On my Ariens, the transmission belt is turning constantly, even before squeezing the handle. So there is at least something else spinning along with the engine, as another possible source of noise. If yours is the same way, it may be worth doing the test, just to help confirm the source of the noise.

If you confirm it's the engine, great, ignore the other stuff. And if perchance the noise changes when you add a belt, then you can better focus your troubleshooting.

PS- If you have a mechanic's stethoscope (like this https://www.amazon.com/ABN-Mechanics-Stethoscope/dp/B01BUJZBOO/), you could use that to help pinpoint the noise location, by touching it to different areas with the engine running. Or you can use something like a rod, with one end against the engine, and the other end against your ear, or the side of your head. Just anything to help transmit noise directly from specific locations on the machine.

Thank you for the welcome and response as well. I'm happy to hear you never had to open up any of your engines.
Yes, on this Tecumseh, there's not much inside once you open it up.
From what I know about my blower: It's driven by chains under the pan which I use a small amount of spray chain lube every 2 years. I'm almost certain none of the 2 belts are turning when the auger and drive levers are in the up position. I replaced both the auger and drive belt 3 years ago. The belts are in great shape as well as the friction wheel and plate.


I don't have a stethoscope. After hearing what I heard, I was afraid to start it again.
 

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Discussion Starter #11
Thanks guys,
I'll post a few more photos later tonight if you guys would be kind enough to take a little further look. I could be missing something from my lack of knowledge. I really appreciate all the help.
 

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Classic cat, I just realized you're in Albany. I'm in Jefferson, Schoharie County a few miles off of I-88
It's a small world !!!!!!! It's freezing up on the mountain for the last week plus. I know you guys are only 10 degrees warmer.
Yep, you're about an hour away. There are a handful of active members from the capital region.

I think we hit 20 today... almost T-shirt weather!
 

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Time to take the side cover off if everything looks good under the flywheel. Sounds to me like the rod bolts may have come loose.
 

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Sorry your last post slipped in just before I hit the post button.

It's cold here too on the other side of Oneonta.
 

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Magnet edges look sort of rough. You didn't find any debris inside or stuck to the magnets?
 

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Discussion Starter #19
Sorry your last post slipped in just before I hit the post button.

It's cold here too on the other side of Oneonta.

Hello deezlfan,


Thanks for the response. Nice to know you're in Oneonta. I'm 27 miles to the Home Depot via the south side route.
 

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Discussion Starter #20 (Edited)
Magnet edges look sort of rough. You didn't find any debris inside or stuck to the magnets?

Nothing at all. It was probably cause by me. I stuck the widest flat chisel I had behind it as I was tapping the flywheel off. I hope I didn't screw up the magnets too much ?
I didn't have a puller.
 
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