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Tecumseh parts swap?


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#1 dodge trucker ONLINE  

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Posted January 10, 2016 - 11:27 PM

OK guys roll your eyes, I know how Tecumseh engines are so "loved" around here.

I'm gonna ask if anyone knows if the crankshafts could be swapped out between these 2 engines, as the PTO ends are different between them and my (hopeful) transplant prospect's crank will not work, as is.

The bad engine, is off of a walk behind snow blower that I dragged home earlier today.

I can tell that somebody has done a teardown of the original engine to determine what it would take to fix, it was all put back together less than finger tight and they left the rings out even, when they slapped it back together.  this engine has the 2:1 extended camshaft, so does the hopeful replacement.

the only real problem I see is that the cam "bearing" (the engine cover) must have seized, the cam is all scored to He11, where it passes thru the cover.  If worst came to worst I could possibly have that reamed oversize, and find a bushing at a bearing supply house to repair the block, it actually looks like the cam took the brunt of the damage. (then I'd have to find a cam, this one's not easy to do that on)

 

both have bronze bushings for the crank journal on PTO end. the block itself looks to be in very good shape on the original engine. (have not actually miked it out though  that engine's junk, as far as I am concerned.. I am gonna harvest all the good parts, for the shelf)

 

anyway here goes;

original engine, Sears model 143.806082 which crosses to Tec model HM-80 155394P   1990 vintage

this is an 8HP, L head engine

hopeful replacement; 11 HP  tec OHSK110  221703A  what I can read off the sticker  I'm guessing this eng. to be 1998. this is OHV engine. (sticker all brown and nasty from fuel leak, due to bad float)

both have same displacement, bore, stroke, and 2:1 extended camshaft. one will bolt directly in other one's footprint. crank height is identical.

 

original engine PTO; 3/4 dia X 2-1/4 long, full length keyway, 3/8-24 threaded in end.

replacement is 1-3/16 (same as main bearing dia) which steps down to 7/8 for about the last 1-1/2" in length, 3-1/4" long overall, same thread in end.

 

original crank has slightly narrower counterweights, larger hole through crankpin (Lighter Counterbalance)

donor motor crank, slightly wider counterweights, smaller dia hole through crankpin.

flywheel taper and keyways are identical

main bearing and crank pin dia. are the same between them.

Plan A; swap cranks, reassemble the OHV engine, bolt it on, done.

Plan B; have replacement engine's PTO end of crank turned down (and cut down an inch shorter, along with new keyway cut in) to match original engine's dimensions. I have the "bad" engine totally torn apart, the hopeful replacement is only apart as far as needed to yank the crank.

My concern (maybe overblown?) is the difference in counterweight thickness, balance...

 

I have had this 11HP sitting here a couple of years collecting dust, have been scouting CL (not very hard LOL) looking for a machine that this engine would work on.  It runs well, just had to replace leaky float that had fuel leaking out mouth of carb like a faucet, along w/a new needle and seat, and new fuel line. at this point, I know that I will have a snow blower for sale once this one is running again. but IDK whether it will be this one or the one I've been using the last 6-7 years.



#2 Tecumseh power OFFLINE  

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Posted January 11, 2016 - 08:15 AM

Is the crank journal for the rod different? It may be a different diameter, the 11 may have a bigger rod not 100% sure and check the stroke too. The heavier weights are because the 11 should have a bigger bore .

#3 Tecumseh power OFFLINE  

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Posted January 11, 2016 - 08:17 AM

Does the hmsk11 run? Why don't you just use it on the blower? If you put why I missed it in reading this only had one cup of coffee lol

#4 chieffan ONLINE  

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Posted January 11, 2016 - 08:17 AM

Sounds like a lot of work to try and save an old engine.



#5 dodge trucker ONLINE  

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Posted January 11, 2016 - 01:17 PM

Tecumseh; same bore same stroke,same journal diameter. Thought I'd said that maybe not.

Chief; there was nothing wrong with the 11 hp motor at all, other than the crank PTO being the wrong configuration for the machine that I plan to use it on, so wanted to see if I could make it work just by swapping the crank from the original engine. I have had this 11hp sitting here a while and want to see it get put on something and used. So I found a machine that takes a dual output setup with a bad engine....

#6 dodge trucker ONLINE  

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Posted January 11, 2016 - 01:23 PM

Does the hmsk11 run? Why don't you just use it on the blower? If you put why I missed it in reading this only had one cup of coffee lol


That was exact the plan until I found out that the PTO ends of the crank was way different the original engine's. So now the plan as listed in my first post above. Yes the 11 runs and really good too.

#7 MH81 ONLINE  

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Posted January 11, 2016 - 06:01 PM

I love the old Teccy's.
I believe the HM80 and the 11 would be way different cranks in heaviness.
I didnt quite understand what you meant when you were talking about the 1 3/16 crank being the same as the main bearing?

Oh, just re read... Maybe I do get it.

I have a idea... If you're planning on throwing the 1 3/16 crank out anyways, it might be worth a try.
Why not turn the crank down? How much of it would you need to do? Do you have metal lathe stuff? Maybe even a good file and a lot of patience... Keyway might be a challenge.
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#8 dodge trucker ONLINE  

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Posted January 11, 2016 - 07:12 PM

I love the old Teccy's.
I believe the HM80 and the 11 would be way different cranks in heaviness.
I didnt quite understand what you meant when you were talking about the 1 3/16 crank being the same as the main bearing?

Oh, just re read... Maybe I do get it.

I have a idea... If you're planning on throwing the 1 3/16 crank out anyways, it might be worth a try.
Why not turn the crank down? How much of it would you need to do? Do you have metal lathe stuff? Maybe even a good file and a lot of patience... Keyway might be a challenge.

what I meant was that the crank is the same diameter as it is in the main bearing area where it passes thru the case for over 2" before it steps down to 7/8"

 

As I said above, having the original crank that came with the 11HP turned down to what's needed for this machine is still "plan B". I do not directly have access to metalworking machines, but have a couple of people that do/ if that is what is needed to make this work.

My thinking was that as long as the bearing diameters (both main bearings and crankpin) are the same, (and they are!) and the stroke is the same between these engines (it IS!)  that I could just drop the crank from the other (junk) engine into the good engine.

that would be easier for sure.



#9 drbish ONLINE  

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Posted January 11, 2016 - 07:53 PM

What we need is a crank spec sheet for the 2 engines to compare.I do not have one for these

Do you have the two cranks part number? 


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#10 drbish ONLINE  

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Posted January 11, 2016 - 08:03 PM

I got the numbers

HM80155394      crank #  36245     

ohsk110 221703 crank # 37283    


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#11 glgrumpy OFFLINE  

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Posted January 11, 2016 - 08:26 PM

Wouldn't it be easier to just get right size pulleys or sprockets or whatever and or easier to rework those than a crank?  Pulleys and sprockets can be bought with just the center core with right size bore and then you buy pulley sheaves or sprockets to fit the needs and they can be pressed on or welded on or whatever to the center bore part. This blower have more than one belt off that shaft? I take it the second shaft is for the drive and is diff speed?  That same between them?  If these cranks are diff weights, would think heavier one in lighter engine is gonna be shaky and vibration?  More power in 11 and this more torque, and pulses the 8 never needed to quell. 

 

OR.......Sell the engine and the tiller chassis, forget about it and move on. GONE! and outta mind, no cost!  :smilewink:


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#12 dodge trucker ONLINE  

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Posted January 11, 2016 - 09:29 PM

no not easier to get pulleys to work with the particular crank configuration of the 11hp.

I dont want to run without a belt cover as i do not want the base of the machine filling up with snow.  current 11hp crank too long.

Yeah I can cut an inch off the length easy enough, but then I have a stub of 7/8" diameter about 1/2" long, steps up to about 1" diam. for another 1/2" of length and then 1-1/4" long, 1-3/8" (not 1-3/16 as I'd said earlier)  to the edge of the pto cover if I were to do that.

 

the crank out of the 8hp is 3/4 diam., fully keyed, 2-1/4 long. 

 

Grumpy; you tellin me nobody has ever put a different engine on a snow blower than original before? ( going by your saying to "get rid of it"....)

the plan was to get the 11hp set up as it needs to be to run the blower then (maybe sell it as a running working machine IF I don't decide I like how it works better than my other one) this one is "trac drive", never had a machine like that before.

and I have a good crank that will work for the machine configuration, if it will work in this other engine. If that winds up being the case, all I'll be out is an engine cover gasket and 2 oil seals, and the machine will live again.


Edited by dodge trucker, January 11, 2016 - 09:31 PM.


#13 dodge trucker ONLINE  

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Posted January 11, 2016 - 10:05 PM

well, I just got off of parts tree, interesting finds.  The piston for the 8hp, supersedes to the same PN as the one for the 11hp...same story on the connecting rod. 

while I do not need a flywheel, both engines call for the exact same PN.

looks like I have a winner... will save bugging my neighbor for a "favor"...I was gonna have him take the 11hp crank to work and have him cut the pto end down to match the 8hp one.

yup the newer OHV engine actually has a larger endplay tolerance than the older L head... I dry fit the 8hp crank in the 11hp and it is definitely within range.

 

the 11 was made during the time when engine and equip companies made "more power" with a decal change, remember the lawsuits?  so I am a bit skeptical that this 11hp engine really is that much more powerful than the original 8hp, with the same displacement/   though OHV is supposed to be more efficient than L head.

Back when the HH and OH engines were current prod., if I remember right the 14hp OH series had the same bore/stroke as the 10hp HH series "L head"


Edited by dodge trucker, January 11, 2016 - 11:23 PM.


#14 MH81 ONLINE  

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Posted January 12, 2016 - 07:44 AM

I think the end game will be seeing if you can swap it in.
Cam gear may be different, some seemingly trivial thing may goof you up, but I'm thinking there is enough spec overlap to tear them down and give it a try.
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#15 dodge trucker ONLINE  

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Posted June 04, 2016 - 09:31 PM

dredging up an ancient thread.... This project got forgotten about, as the snow that we usually get, didn't happen// and other things with more importance got worked on, while this one collected dust/  I got tired of most of 2 engines eating up my workbench space, and really need that freed up pretty badly.... so I finally put this all back together, and fired it up today.  Runs fine, smooth as can be, no vibration, I started it up not bolted to anything// and watched it "jitterbug" all around the concrete garage floor for about 15 minutes.....so now I can finally "junk" the rest of the remnants of the 8hp.... now that I know what I will/won't need from that one to make this one work... got me a fully adjustable carb that will find a home on my Deere 828D so that I can finally fix the surge that "that" one has had when ever "not" under load ever since I got it.   Oh and a good spare electric starter.  otherwise the rest of it.... scrap metal.


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