# Tecumseh HM80 Parts



## ManicMechE (Dec 13, 2007)

Hello - new to Hobby Talk and new to small engine repair, so bear with me. I'm working on an Ariens ST824 snow blower (model no. 924050) with a Tecumseh HM80 (model no. HM80-155128J) with electric start. I've (somehow) managed to get everything in working order, but I'm almost certain that it's not going to stay that way, so I need to get some replacement parts. 

The engine is the biggest problem at the moment. When I got it, it would turn over, but the starter made an awful racket and kept getting stuck engaged with the fly wheel. Took that off, opened it up, the journals were bone dry, so I put some heavy oil on them (Penn reel lube actually), greased the pinion, now it works fine. 

I was getting no spark, so I pulled off the flywheel to check out the ignition. Turns out the magnets glued inside had come off and in the process smashed up the primary on the magneto pretty bad. On a whim I glued them back on, guessing on the orientation and following the outlines still visible on the edge, and put it back together... and after a bit of cranking it started right up. It runs a little rough, and needs a lot of cranking and fiddling with the choke to start, but it runs. (I'm completely baffled... from what I hear, the clearances between the primary and magnets is supposed to be thousandths of an inch, and the primary look like someone smashed it with a hammer. Repeatedly). 

(insert) I just changed the oil (it was nothing but sludge) and it runs a bit better now.

Anyway, I'm almost certain that I need a new flywheel and at the very least a new set of coils. The problem is that when I got the parts list online (from http://www.outdoordistributors.com/), there are numbered arrows on the diagram pointing to the ignition assembly and flywheel, but no corresponding entries in the list. I've tried searching Google for "tecumseh hm80 [part]" but the parts that come up don't look right. Everything I've seen is for an HM80 with the magneto outside of the flywheel, and this one has the entire ignition inside/underneath the flywheel. I've emailed Tecumseh and requested a parts list, but I'm not sure if that will be any more complete when and if it arrives. Any suggestions? Any help would be greatly appreciated. Thanks.


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## pyro_maniac69 (Aug 12, 2007)

yes it does sound like you need a new flywheel, is those magnets came off once, there is a good chance they will come off again. Now getting the coil bracket is another story because you can't get the coil part from Tecumseh anymore, you can only get it aftermarket. They still offer the points and condensor, but thats it. Let me know what you want by the end of the night, and I can get you some prices by tommarrow afternoon


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## 30yearTech (Sep 14, 2006)

The flywheel and stator for your engine shows to be NLA (no longer available), unless you can find another junk engine to steal these parts off you may be out of luck. The flywheel would be the most important part to find, the stator was pretty common on older Tecumseh engines and you should be able to find one that would work. The coil, points & condenser are all still available. 

Heres a list of the part numbers, they may help you to track something down:

610847 - Flywheel
30561B - Stator
30560A - Coil


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## ManicMechE (Dec 13, 2007)

I'm actually stuck at my parent's place (they won't let me leave) because of this Boston area storm, so I'm not where the snow blower is. From what I remember, it looks like I'll need a flywheel and primary at the least, possibly a secondary as well (the spark plug wire is looking iffy and I think it's permanently attached). I've done a quick google search for the parts, and it looks almost like I could buy a new engine for the prices people are asking. Is it worth it? Also, if I do replace the ignition components, how do I gap them properly if everything is under the flywheel? Thanks.


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## 30yearTech (Sep 14, 2006)

A new engine may be a better course of action if the rest of the unit is in good shape. As parts become harder to find the price also tends to skyrocket, and it's simply not worth it.

You set the points with the flywheel off, you do not have to set the air gap on this type of system, but you should set the timing, to do this you would need a dial indicator and a continuity tester, or you can remove the head to measure the piston position when setting the timing.


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## ManicMechE (Dec 13, 2007)

I wouldn't really say that the rest of the snow blower is in good shape, but I'm pretty good at keeping things running if I can get or fix parts. 

So (forgive me if this is is a somewhat obtuse question, and correct me if necessary), if I get a new engine it should probably be the same horsepower rating, the distance from base to crankshaft centerline should be the same, the PTO end of the crankshaft should be the same diameter and keyed, the distance from engine centerline (according to this diagram http://www.tulsaenginewarehouse.com/catalog/tecumseh/specs/hm80100/) to the engine face on the PTO side should be the same, the offset from center of the crankshaft should be the same, the locations/dimensions of the mounting holes should be the same... If I got another, hopefully more modern HM80 or HMSK80 would all of this stuff be similar/close enough, or do I have to scrutinize the engine schematics? 

Looking (briefly) at the diagrams for the HM80 and HMSK80 (http://www.tulsaenginewarehouse.com/catalog/tecumseh/specs/hm80100/ and http://www.tulsaenginewarehouse.com/catalog/tecumseh/specs/hmsk8090100110/ respectively), the only critical difference I can see is the distance from engine centerline to the engine face on the PTO side. Considering that the diagrams seem to apply generally to the indicated models is it safe to assume that all revisions will be the same dimensions? The engine on there now is an HM80 but it looks an awful lot like an HMSK80... but I'm not near by so I can't measure it. 

I actually can't afford a new engine at the moment (I got the snow blower for free because it didn't run), but I'd like to be ready for when I can. Thanks.


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## 30yearTech (Sep 14, 2006)

For the most part the dimensions should be close enough to swap out with little or no problems. Just make sure the diameter of the crankshaft and key way have the same specs as the old engine, or you may have to replace the drive pulley/sprocket etc...


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## ManicMechE (Dec 13, 2007)

so, now that it's snowing, I discover that the engine won't run when hot. It's a little difficult to start, but it seems to run fine when it's cool. After about ten minutes, when it warms up, it runs very rough, surges, and won't stay running at full throttle. As it gets warmer, I can keep it running if I back off on the throttle, but then it does the same thing and I have to keep backing it off until it's at minimum. If I hold the governor back, it will run a little better and even stay that way for a couple seconds after I let go, but then it gets rough again. 
It sounds (sputtering) and smells (gasoline) like it's running rich, and at times it spews quite a lot of black smoke. I'm reading the service manual now, but if anyone has any good suggestions, please help. Thanks.


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## ManicMechE (Dec 13, 2007)

I managed to get it working enough to clear my driveway. There's something wrong with the carb, but I'm not sure what. I could only keep it running by fiddling with the main adjustment screw every few minutes, and to start it again I had to back the screw out about a turn. I guess I'll take it apart at some point, blast it out with carb cleaner, and see if anything seems amiss.


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