# John Deere 826 - Connecting Rod broke



## silverviper (Nov 26, 2010)

Hello. I have a JD 826 that I inherited from my Dad. The snowblower is roughly 40 years old, early 80's with the short chute on it. 7 years ago I was using it and didn't realize it was burning through oil so quickly. Well at that time it came to a screeching halt and the connecting rod broke due to lack of oil i'm assuming as there is maybe an ounce left.

I would like to repair the motor and keep it original. I have never broke an engine down like this before but I know my way around a wrench. It has the 8hp Tecumseh on it. I started stripping down the engine last week and just need to take the mounting bolts off. The piston with the connecting rod fell out when tipped it upside down. I haven't tore it down to the point of looking at the crank or camshaft yet, I just need to pull the motor off. I noticed a couple knicks on the edge of the piston and a scratch (see pics). Are these ok to proceed or do I need a new piston as well? The cylinder wall feels smooth, the engine block is fine. How do I know when the piston ring are worn and need a replacement? Any advice would help. Thank you.


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## jherbicide (Oct 14, 2021)

(to do it right: You need to measure engine bore with a dial gauge (plenty of info on google), and also inspect it for rough spots.

Chances are you'll have more time and $ invested in a rebuild vs re-powering with a Harbor Freight engine (also tons of info in regards on this forum).

Its just my guess but I think at minimum you'll need a new piston/rings, a bore job, and a new crankshaft. If you go cheap and try to reuse stuff you'll gambling on it all going wrong again in short order.


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## Oneacer (Jan 3, 2011)

As long as the machine is in good shape, myself, I would probably opt for one of the OHV Predator 301cc on sale this week at HF ....

Bolt on and done ..... instead of dumping money into an old-style engine over 40 years old.


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## badbmwbrad (Jul 30, 2019)

I wouldn't want to see anything but the original engine on my dad's snowblower. To do otherwise is to spoil a lot of good memories. Maybe you can smooth over any raised metal on the piston with Emory cloth? The piston rides on an oil film established by the oil control ring (the one with the holes in it). 

The piston ring's sealing surfaces have to be in very good condition and I would think that new piston rings should be used along with just a light hone on the cylinder to remove any raised metal and to re-establish cross-hatching marks so that the new rings bed into the cylinder. I read that the cross-hatching marks have to intersect at a 45-degree angle for best results. You probably don't want to use very slippery synthetic oil for a while in order that the new rings and cylinder surface are bedded into each other. 

Race engines don't get any oil pre-wetted onto the cylinder wall before they're started! The engines are started with non-oil-wetted cylinder walls and then they're run at several thousand RPM for one minute then shut down to cool off. This immediately beds in the piston rings. Of course, the race engine only needs to last for one race before it's rebuilt again. Your engine should have its cylinder walls pre-wetted with a lubricant.


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## deezlfan (Nov 8, 2017)

There really is no justification to pour big money into an old Tecumseh H80. Just finding a small engine guy to do a cylinder bore doesn't make sense. Oversize pistons don't exactly grow on trees either.

Based on your statement about the bore and block and assuming the cam and crank aren't wasted, I would buy an aftermarket rod, dress the raised or rough areas of the piston with a clean mill file to remove the high spots and put it back together with the rings you have.


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## Ziggy65 (Jan 18, 2020)

I understand wanting to keep the original HM80 on your Dad's machine and if you enjoy turning wrenches it can be a rewarding project. I agree with what deezlfan recommends, I probably wouldn't invest hundreds of $ into the rebuild. 

There are usually lots of good running HM80 used engines for sale on Facebook market place, Kijjiji, etc. for $50 -150.00 and no modifications will be needed. A John Deere Yellow spray bomb and utilizing some existing parts from your engine (heater box, fan shroud, gas tank etc) no one will know it's not original.

If originality is not important that 301cc Harbor freight looks tempting.


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## rwh963 (Nov 21, 2019)

what would dad do? he'd get a predator!


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## Jackmels (Feb 18, 2013)

Find a similar 8hp engine, and swap the sheet metal and gas tank from the orignal engine.


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## silverviper (Nov 26, 2010)

rwh963 said:


> what would dad do? he'd get a predator!


lol this might be true. There are memories of him cursing the thing out for not starting.


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## silverviper (Nov 26, 2010)

Thanks guys, I’ll take it under consideration. I first want to get a look at the crank and cam and make a decision from there. If I do go about replacing the connecting rod, I’m not looking to drop big money into it. I found a ‘new’ vintage rod on eBay for $50. A new predator engine sounds tempting as well. This would be basically a backup blower or for small snow event jobs. My main blower is an Ariens Deluxe 28.


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## tadawson (Jan 3, 2018)

Rod, a light hone and rings (heck, you are there . . . change them) will likely get you going. A trick I came up with to determine any taper, etc. in the cylinder is to insert a ring, and measure the end gap as you move it up and down in the cylinder - some simple math will tell you the variance, and if you can get a proper end gap with standard rings, you will also know that it has not worn oversize. No real need to bore oversize unless things are verhy ugly . . . Much more than that, and replacement may be warranted (and no, I am _NOT_ recommending a Predator . . .)


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## farmer52 (Dec 27, 2020)

Where are you located? No location listed in your profile!

There are several JD826 machines listed on Craig's List at reasonable prices. Depends on your location.


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## Hec In Omaha (Jan 10, 2021)

Silverviper,

If you are not in a hurry and have a back up snow blower to use, why not hand the engine over to your local Junior or Senior High School Power Mechanics shop class and let them go through the engine? You can supply the parts as needed and the kids get hands on experience with a small engine project/repair. I took power mechanics in 7th grade and rebuilt an old Tecumseh 8 HP, Ford Pinto 4-cyl Engine, 4 speed manual transmission, and rear differential. We had to finish all those projects by the end of the year! Most projects were supplied by the school but you were allowed to work on stuff brought in as well! For the small engine we did a complete disassembly, inspected all parts, reconditioned the cylinder bore, did a valve job, carb rebuild, points and timing, bearings, governor adjustment, reassemble everything to spec and had to show the engine would run on a bench and dial it in. I loved that class and still use what I learned today! 

Hec


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## Oneacer (Jan 3, 2011)

Do they still have shop in the high schools?


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## Hec In Omaha (Jan 10, 2021)

My kid's school does, however the class is called industrial technology. I guess it depends where you live.

Hec


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## WVguy (Nov 24, 2018)

My high school did, but I graduated in 1968 so not sure about now.

But I made a memory when I could bring my motorcycle into the shop class and then rode it down the hallway on the way out. I was given a "talking to" about that one....


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## JJG723 (Mar 7, 2015)

My old high school is a vocational and technical school so the shops are front and center. All projects from the outside are accepted. Great real world learning.


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## silverviper (Nov 26, 2010)

Oneacer said:


> As long as the machine is in good shape, myself, I would probably opt for one of the OHV Predator 301cc on sale this week at HF ....
> 
> Bolt on and done ..... instead of dumping money into an old-style engine over 40 years old.
> 
> View attachment 205597


Even though the sale is over, i'm still mulling this option. The one thing holding me back is the 8hp 301cc has a 1 inch shaft while the 6.5hp 212cc has the 3/4" shaft like my original Tecumseh. I would need new pulleys for the 8hp, and i'm not sure a guy could find the dual pulleys easily.


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## silverviper (Nov 26, 2010)

I found some time today to remove the engine and open it up. As expected, several remnants of the connecting rod were sitting on the bottom. The block, cylinder, and cam look flawless. The crankshaft however is dinged up and has what looks like aluminum casting transfer on it from the connecting rod. I can feel grooves/roughness by touch. Any thoughts if this is salvageable?


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## tadawson (Jan 3, 2018)

Muriatic acid and/or fine emory cloth and the aluminum residue should come right off the crank. Surface buildup from a failing aliminum rod rarely damages the steel crank.


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