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Generac / Tecumseh Info needed


I have an old 5000 watt brushless Generac generator Mdl: 01140-2 that is powered by a Tecumseh 10hp engine mdl: HM100 159436P. Apparently this particular generator was assembled years ago in the UK. With just under 2,240 hours the engine is nearing the end of its life but the alternator is in great shape and I was considering re-powering it with either a new old stock Tecumseh or some other brand, however as I have been told Tecumseh had a rather odd tapered shaft and many newer generator engines will not fit the taper of the alternator. I tried contacting Generac but it would have been more helpful if I had spoken to a rock in my yard.

I am trying to figure out which engine shaft this genset has. According to the Tecumseh Service and Accessories manual I have this engine could have had either a 2-51/64" tapered shaft p/n 35441A or a 4-21/64" tapered shaft p/n 37302. Short of taking the genset apart is there any way of knowing which shaft this engine has?

Any info would be appreciated.

Thanks to all.

Andrew Mackey

Last Subscription Date
Have you checked out the engine itself? How do you know it is trashed? The older techumseh engines were well built work horses and with regular mantainance, will work well beyond the hours you state. your main wear points: Valve stems and guides (relaceable), rings, and the carb throtle shaft bushings. otherwise a very sturdy engine as long as oil was changed and the level kept up during its service life. it is definately geting harder getting techumseh parts, as old stock is getting used up though. As long as the cylinder is in good shape, you might be betterr reconditioning the curent engine. At the very least, get your parts now and do the servicing as needed. Finding a replacement engine may be difficult. Deck to crank center, side to side center, taper and shaft length all come into play. A NOS HM-100 may be unobtanium but you never know what is still out there .

I agree, dealing with generac is a real PITA. They just want to sell new units, and their service just plain sux. my son used to work at a shop that worke on them, and even he, as a dealer, could not get information out of them. frustrating does not describe dealing with them!:mad::mad::rant: Perhaps an old mower shop would have a service book on the techumseh engine that would give your answer. i do not know if techumseh put their part numbers on the crank, so a tear down may not help inless the parts book gives specific dimensions for the crank.


In response to Andrews comments, I just assumed, perhaps prematurely, that with that many hours on it it was nearing the end and I wanted to see what options I had before it gasped its last breath. Aside from a small oil leak from the breather assembly (Replacement parts should arrive tomorrow) the engine appears to be running just fine.

I have always liked Tecumseh engines and never understood why they get such a bad rap. I guess I just never realize that they would be as long lived as you state and assumed it was nearing the end with the hours it had on it since non of the Briggs engines I've had on other equipment lasted nearly as long.

Over the years I've had the generator aside from regular oil changes every 50 hours using synthetic oil the only modifications I made was to replace the carburetor intended for the HMSK100 engine because the generator was almost impossible to start in the winter with very cold temps. Since the replacement 1 squirt of the primer bulb and it starts on the first pull, I also changed the flywheel and added electric start. Oh, and I've never used gas with Ethanol in it.

So this little engine may still has some life in it after all. Many thanks also to gdstew for the shaft info.

Thanks for your comments they were appreciated.