HELP - I need some advice on how to proceed - repower? - Snowblower Forum : Snow Blower Forums
 
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post #1 of 7 Old 03-23-2015, 06:29 PM Thread Starter
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HELP - I need some advice on how to proceed - repower?

Hello everybody, I am new to the forum but have been following it all winter. I was able to restore a 35 year old Craftsman 5/22 with advice found on the site.

A bit about me and then to my dilemma... I am a 57 year old mechanical engineer that works for the Navy designing/modifying/modernizing the various propulsion systems utilized on our surface ship. I am also a true gear head having worked on anything that runs on gasoline or steam since I was 10. So, I know my way around machinery and pride myself in being able to repair or rebuild almost anything mechanical.

Now to the dilemma... my neighbor has a 15 year old MTD/Yardman 8/24 that he neglected to ever replace the shoes on and subsequently wore the skid plate and auger housing down to the point of the auger almost touching the ground. Okay, no problem, find a new chute and install. The ones we found new were almost $300 bucks so I said let's find a junker we can take the chute off of and transplant to his machine. He finds a machine at the local repair shop that is hardly used but has a blown engine. It is a 8 HP MTD/Yardman as well but it is a 8/26 (bigger housing). I decline to go look at it first (a mistake) and tell him to just buy it. He got it for only $80. I told him we could just swap his well cared for 8HP Tecumseh onto this machine and go. He brings it home and it is, as described a virtually new machine that had a blown Tec 8hp. Fast forward to this last Saturday: After consuming a "few" judgment altering beers four of us decide we are going to do the engine transplant. The first thing I notice once I get the belt covers off both machines is that the old machine has a two shaft engine while the "new" machine is a single shaft. The machines had a completely different belt/tensioner/pulley set up. and a completely different configuration and sized chute housing. Bottom line, the engine swap was not going to work, or at least be simple. So, long story short we decide to mate the old frame with good engine to the new auger housing.. (beer affected judgment) led to ir-reversibly butchering up the old frame and engine mount to make it mate with new housing. That did not work! So here is the dilemma... I have the new frame and auger housing, along with all the supporting belt drive components in one piece, unbutchered in any way. NOTE: The running engine's crankshaft is different than the single shaft originally installed in the new carcass (blown engine). It is not machined properly to allow the single shaft components to mount up. I think I have two options and this is where I need advice. Do I 1) Repower with another (predator?) engine that is a direct bolt on or 2), do I try to take the crankshaft out of the blown engine (I think it is in good shape) and transplant it into the running engine? I sort of put myself in this position by "thinking" I knew more than I did, figuring all large frame 8HP MTD/Yardmans were the same. One last note, both model numbers are un readable.
My friend and neighbor is sort of pissed at me so I need to make this right.

Any advice is much appreciated. This is truly an awesome site!

Royce (Alexandria, Virginia)
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post #2 of 7 Old 03-23-2015, 08:29 PM
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So to recap..you have a good running 2 shaft engine that you want to transplant onto a frame with a single shaft motor.

Try checking the drive components of both units. Some MTD units have simple drive systems that have only one gear that is turned by a splined hex shaft, this system can be easily flipped to reverse the drive direction. You may also find a more complex drive system consisting of multiple gears. This one won't flip, but it could be removed and replaced with the components from the other chassis. MTD hasn't made significant changes to the tractor body in the last 15-20 years, while the internal components of the drive system may be different, you should notice that the location of the wheel axle shaft and the hex shaft will be the same, allowing you to move components from one chassis to the other.
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post #3 of 7 Old 03-23-2015, 08:39 PM
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pull the crank off the bad engine and transfer it. not a hard job, just remove the sump cover and remove the rod bolts. pull off the shrouding and pop the flywheel with a prybar behind it and a mallet on the crankshaft. probably will take an hour to do both engines
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post #4 of 7 Old 03-23-2015, 08:43 PM
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You might look at the Predator repower and then sell the other engine.. You might end up ahead in the end...

Ariens Platinum 30
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post #5 of 7 Old 03-23-2015, 09:43 PM
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Swap the cam, crank and sump cover from the blown engine to the good engine. If the blown engine threw a rod (which is more or less the only way a Tecumseh blows up) you will need to clean up the crank journal, it will look terrible, but it's just aluminum transferred to the cast iron crank, polish it with some emery cloth and it will be fine.
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post #6 of 7 Old 04-13-2015, 05:46 PM Thread Starter
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Talking Update to my original thread

Hey guys, thanks to those that responded to my dilemma with sound advice. On Saturday I swapped the crank, cam and front cover from the doner single shaft engine into the original double shaft engine case utilizing the existing rod and piston assembly. Worked like a charm and my neighbor/friend now has a like new machine with the bonus being the chute is 26" vice 24". This forum is awesome.

Last question. I now have the parts leftover to reassemble the double shaft engine into a serviceable short block. Is this worth doing? Is there a market for selling this. The parts are in excellent condition. It just appears that the engine was left out in the rain with no spark plug allowing water to enter the cylinder and rust up the rings. All internals are rust free and the rod/piston assembly is intact. Even the piston is clean... just rust stained from rusty rings. Thinking of re ringing and honing rust stains out of cylinder. No scoring on cylinder walls either. This was an extremely low hour engine to begin with.

Your thoughts appreciated.
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post #7 of 7 Old 04-13-2015, 06:02 PM
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Dual shaft engines are worth a bit of money, they're getting harder to find and it's not that easy to retrofit something else in its place.

If you re-ring it and put it back together and have it running you can probably get $150 out of it.
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