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Tecumseh HMSK85-155901A
Sears 247.888500 MTD snowblower

This my personal project snowblower I bought back in fall 2012. Bought it and pushmower for $45. Snowblower threw a rod and cracked the block. Pulled crankshaft cleaned it up some. Its not perfectly smooth but not extremely grainy either. Measured the crank rod journal at 1.371 diameter (in the middle) and 1.374(outside). The crank rod journal spec is 1.374-1.3745. Crankshaft is NLA. I wanna gamble and reuse the crankshaft but I also dont want to throw another rod either. I already have used bare block coming.

Here's pics of the crankshaft rod journal.

I would not use that crank without a lot of cleaning and then remeasuring to see how far out of specs it is. A new rod won't last very long on that crank the way it is. Also check to is if it is out-of-round. I'm betting that after cleaning it will be.

Yeah, you got a lot of buffing to do.

Fish said:

Yeah, you got a lot of buffing to do.

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Thats what it looks after using wire brush. Not sure if it will get any better. Someone told to use this to clean it better. Shop Crown Gallon Muriatic Acid at Lowes.com

Muriatic acid will clean the aluminum off, but I think I see some galling on the shaft, which will take some sanding and buffing to get out. This will reduce the shaft size.

Rivets said:

Muriatic acid will clean the aluminum off, but I think I see some galling on the shaft, which will take some sanding and buffing to get out. This will reduce the shaft size.

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I can clean aluminum off. Then I will probably chance it use it the way it is afterwards.

Yeah, it looks like it is just pasted on aluminum, take it off, and you should be good to go.

Fish said:

Yeah, it looks like it is just pasted on aluminum, take it off, and you should be good to go.

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Thats what I was thinking. I found used crank for $50 after shipping on ebay.

Just take the sandpaper and the crank, and buff while you set at the computer, it will eventually buff out.

Soak the crank in the acid, don't sand. Acid will only remove the aluminum, while sanding will remove aluminum and iron, changing the diameter.

Rivets said:

Soak the crank in the acid, don't sand. Acid will only remove the aluminum, while sanding will remove aluminum and iron, changing the diameter.

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Nah, I have to disagree, just buff out the aluminum......... Slap on a new rod, check for slop..... If you buff out all of the aluminum transfer, you will be good to go!!!

Mr. Fish my spelling may not be right in the other thread you commented on, but it is the engine control cable. Also, I have been rebuilding engines for more years than you would give me credit for and sanding or buffing any rod shaft is going to remove material. Trying to buff out that kind of damage is a waste of time and effort and could result in more damage.

I would acid clean it. Then wet buff it.

Rivets said:

Mr. Fish my spelling may not be right in the other thread you commented on, but it is the engine control cable. Also, I have been rebuilding engines for more years than you would give me credit for and sanding or buffing any rod shaft is going to remove material. Trying to buff out that kind of damage is a waste of time and effort and could result in more damage.

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I sure have to agree with Rivets here. I have rebuilt enough engines to know better. But seeing everyone knows so much I say go for it so what way you can do it over. I haven't got any of my money or time into this job what so ever. I am sure glad you aren't rebuilding that engine for me.

Carscw said:

I would acid clean it. Then wet buff it.

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Now is this something you would do on one of your racing engines?

reynoldston said:

Now is this something you would do on one of your racing engines?

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No this is not what I would do on my race engine.

I would acid clean then turn the journals down and rebalance the crank. Install new rods and bearings.

When ever you spin a crank bearing I always replace the connecting rods.

On a small engine crank I would just clean it then buff it with a buffing strip not sandpaper.

Carscw said:

No this is not what I would do on my race engine.

I would acid clean then turn the journals down and rebalance the crank. Install new rods and bearings.

When ever you spin a crank bearing I always replace the connecting rods.

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It sound like you have a complete machine shop set up. Why wouldn't you do the same thing with a small engine? I wouldn't rebalance a small engine but I would have the other work done. I don't have the set you do so I have a machine shop do my work. I pass the cost onto the customer but its done right.

In the very first post the OP stated that the journal was already .003 undersized. That was with the aluminum transfer still on. When removing that aluminum it will be even more undersize and there is no undersize rod available for that engine. Cleaning and putting in an original rod is throwing away money. It just won't last long enough to make it cost effective. Only smart way to savage this engine is to obtain a good crank somewhere and then install a new rod. In my opinion the OP would be better off finding a different engine to use on the unit.

Rivets said:

In the very first post the OP stated that the journal was already .003 undersized. That was with the aluminum transfer still on. When removing that aluminum it will be even more undersize and there is no undersize rod available for that engine. Cleaning and putting in an original rod is throwing away money. It just won't last long enough to make it cost effective. Only smart way to savage this engine is to obtain a good crank somewhere and then install a new rod. In my opinion the OP would be better off finding a different engine to use on the unit.

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I found used crankshaft for $50 on ebay. These engines are hard to find. This is a twin cam engine. They dont make twin engines anymore since Tecumseh got bought out back in 2007.

10HP Tecumseh Engine 7 8" Crankshaft 35980A LH358SA HM100 HMSK100 HMSK80 | eBay

I got few other people looking and asking around to various people in my area for complete engines that might still run but been sitting.

Rivets said:

In the very first post the OP stated that the journal was already .003 undersized. That was with the aluminum transfer still on. When removing that aluminum it will be even more undersize and there is no undersize rod available for that engine. Cleaning and putting in an original rod is throwing away money. It just won't last long enough to make it cost effective. Only smart way to savage this engine is to obtain a good crank somewhere and then install a new rod. In my opinion the OP would be better off finding a different engine to use on the unit.

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I have installed undersize bearing inserts. And as I recall on some of the old engines the mechanic had to pour the bearings and then scrape them to fit. This is before my time so I never did it. What I have did was on the old Chevy engines they shimmed the rod caps. What has to be done with plasitgauge and it will give you your oil clearances. On the smaller engines I see most rods are made without bearing inserts and I don't know if you can buy them undersize seeing I never tried to buy one.

95% of small engines do not use bearing inserts. Company's do make rods for crankshafts that become worn and need to be recut undersize. In this case there is no undersize rod available. As Reynoldston started plastiguage is a great tool to tell you the clearance between bearings and journals, but will not tell you if the parts meet specifications.

I cheated,ive just taken my cranks to a napa engine shop,20 bucks cleaned up crank

I went ahead and bought that used crankshaft on ebay instead of trying reusing the one I have. So hopefully I have this up and running before we get 24in+ in deep snow.

Just to give an update. After finding a used crankshaft and bare block. I also bought new connecting rod, STD piston assy., crankshaft seals, and gasket set. Got the engine back together today. I went to today to look at friction disc drive on the 247.888500 snowblower. Found I need a new friction disc, new rubber wheel, and all 3 belts.