Tecumsah Snowblower Problem

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  #1  
Old 03-01-05, 06:38 AM
TomNJ
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Tecumsah Snowblower Problem

I'm a new poster to this forum steered here by a friend. I've been having a persistent problem with my Tecumsah-powered Ariens snowblower. I've had the blower for a number of years and, up to now, it has worked beautifully. This year, during the first snow we had here in NJ, I was about a half-hour into cleaning the driveway when the blower sort of backfired through the carb and stopped. I could get it started again using the choke but it wouldn't run very long. But let it sit for a while, and it would run again for 15-20 minutes, and then just suddenly stop.

Three trips to the local repair shop and it continues to exhibit the same problem. First trip the shop rebuilt the carb (despite the fact I had done a rebuild just before bringing it), installed new points, condenser and plug, changed the gas and put a new gas cap on and sent me on my way. First snow after that repair the same problem occurred--it died about 20 minutes after starting to use it. When I took the machine back the second time, they ran it for a while and told me the gas level in the tank was too low and that was causing the problem. Took it home. Same problem. Back to the shop late last week, they adjusted the governor and the carb and said they ran it for 20 minutes in the snow without problems.

Took it out early today to clear the driveway and walk following last night's snowfall, and, yep, had the same problem. The blower runs fine for about 20 minutes to a half hour, tosses snow nicely and has plenty of power. Then suddenly it will just cut out. It will not restart unless you flip the choke over to full, despite the fact the engine is warm. After flipping the choke off, it will then run for a short period and stop. Let it sit for 15 minutes and it'll start right up and run for a short period, then die again.

There aren't any decals on the blower that tell me the engine HP but the engine number is H70 130216D SER 8020D. The Ariens frame has two numbers, 7-10M 143539 and MOD 310862. If any one can offer any advice as to what might be causing this problem so I can use my snowblower reliably again, stop dealing with the the repair shop--and stop shoveling snow!--I would be much obliged.

Thanks for you help
Tom in New Jersey (with the sore back!)
 
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Old 03-01-05, 10:13 AM
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It will take a bit of diagnosing on your part, which I'll walk you through. Next time out, have a new spark plug handy, in your pocket. The moment it stalls/quits, remove the plug wire from the installed plug, insert the new plug into the wire, lay it on the head, pull the engne over a visually check for spark at the new plug. If visible, it should be a deep blue in color, not white or orange. If blue, ignition is good. If good, you'll want to get your hands on a leak-down tester in order to check the combustion chamber for any leakage, as I would suspect trouble here if the ignition is good. If you can at least get a compression tester and check such, the reading should be around 60 psi or better. Now this doesn't necessarily tell you where the source of the leakage is, should it be low, but it won't hurt to remove the cylinder head and replace the head gasket. While you're there, use emery cloth and clean the face of each valve and inspect for pitting/wear as well as de-carbon the entire combustion chamber. If spark is white or orange, ignition is weak. Now, I ask, did this shop install new, genuine Tecumseh points & condensor? If so, and the ignition is weak, how is the ignition coil? I'd say bad. This is rare however. If aftermarket points & condensor were installed, I suggest genuine parts. Tecumseh part numbers for reference: Points - 30547A, condensor - 30548B, coil - 30560A, head gasket - 32631A. Head bolt torque will be 200 in. lbs. Whew! Didya get all that? Let us know.
 
  #3  
Old 03-01-05, 05:15 PM
TomNJ
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Puey: Thanks very much for your help. I saw your message when I got finished with work tonight and I went right down to play with the snowblower a little. I pulled the shroud around the carb off. Then I pulled the plug out and checked the compression cold. About 62 pounds. Then I started the engine--fired up first pull as usual--and ran the engine 'til it quit. Not quite 25 minutes, but I was right there--though I probably inhaled more carbon monoxide than I needed. Though I didn't have an extra spark plug, I did have a plug tester in my kit and connected it up immediately. Nice bright blue spark.

Just for the heck of it, I pulled the gas hose off the carb. Not much more than a dribble. Then ten seconds later a flood. Since they changed the gas cap when I had it to the shop the first time and its still doing the stall out bit, I'm guessing the hose must be collapsing and stopping flow. Now I've seen this on cars, but I can't believe the little bit of a flow coming from the tank to the carb would get stopped by a bad hose or that there's that much suction on the line. Nevertheless, I'll replace the hose tomorrow and see if it runs for a longer period. The clue about the fuel stoppage was right in front of me and I missed it. Even after it stopped, the engine would restart when the choke was flipped to full, though it ran crappy.

I want to thank you again for walking me through the diagnosing of the problem. I had just about thrown up my hands in despair. At least now I know something simple is going on and it's not what the experts thought it was. I can't tell you how frustrating it is to drag the machine onto the truck then drive it over to the repair shop only to have some small engine expert blow you off with the advice that the fuel tank was too low with about a quarter tank of gas. It goes to prove again the value of forums like this one where people with knowhow are willing to share their time and knowledge with those with problems. Thanks again. I'll let you know what happens once I change the hose.

Do you have any idea where I can find out how old the machine is? Is there a list of serial numbers somewhere I can check it against?

Regards to the cool!
Tom from New Jersey
 
  #4  
Old 03-02-05, 11:48 AM
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I wouldn't assume that the "new" fuel cap is new nor that it is the right one. It is unlikely that the fuel line is collapsing, although being an older machine it is possible. If the line is original and also likely not braided then varnish could certainly have weakened it. But, I'm more inclined to believe the fuel cap is not breathing properly. Try running the engine again and at the point it flutters, loosen the fuel cap. If the engine picks up and runs well (give it 2-3 seconds to catch up), go to another Tecumseh dealer and buy part# 34210, fuel cap. If loosening makes no difference, go ahead and replace the fuel line with Tecumseh braided. As for the age, the first digit of the engines' serial# tells you the year - "8". But it does not tell you the decade. Based on my knowledge of the model number of both equipment and engine, I say it is a 1968.
 
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