That did not sound good. Tecumseh 7hp Snow King engine. Looking for advice.

So I was out using the snowblower today and right at the end, it started to get loud making a chaw, chaw, chaw sound and getting really loud. It went KA-CHUNK and stopped. Crap. I get it into the basement and remove the cowlings and top of the engine. After it cooled I worked the flywheel and jammed my finger in a fin and the coil thing which hurt like heck. The cylinder went up and did not go down. I pulled it out and yeah, the connecting arm is done for. I checked the cylinder and there is just a little scoring on the lower end of it in a small area. It is very minor I think. The piston has two score areas, one a little deeper that the other. The piston came right out and the cylinder walls were covered in oil. There was no fight getting the cylinder out. Taking the top of the engine off there were two bolts opposite of each other that were loose and the threads were oil coated. I think these two bolts leaked air at the gasket and there was a bit of a carbon ring at the top of the cylinder.

So, go easy on me here, I have not done more that changing oil on my truck and replacing plugs. I have this torn down pretty well and will have no problem re-building it. Some of my descriptions of parts may be off, but I think I can get the point across. I have a few questions based on the pics.



One question is where the bolt pushed through to the inner ring of the lower connecting arm, I think the crankshaft where the connecting rod meets may have been scored. Any concern with that? You can see where the the threads pushed through a little.



Two views of the piston. Replace it?



Slightly deeper.




Top of cylinder, carbon build-up.



I did watch a brief re-build on Youtube to familarize myself with what I am geting into. I will order new rings, head gasket, gear case gasket and a connecting arm. I am going to tear off more this evening and
inspect the crank shaft. Everything turns smooth otherwise.

I guess this was a good time to happen as it needs new belts as the transmission and throwing capability were starting to decrease, so I will really tear into this thing. Thank you all in advance. I never though I'd be posting questions in the power equipment forums.

 

Your probably gonna find out that the cost of the parts are not that far off a replacement motor. The days of rebuilding those single cylinder air cooled motors have passed. They are designed with a 300 hr life span on purpose. If you go to Tractor Supply or Harbor Freight, you will see the economics are there to just replace the entire motor.

 

I'll get pricing on parts and see where we end up. This machine really owes me nothing.

 

One other question: Is there a bearing set that goes around the crankshaft where the connecting rod attaches? I found the schematic online and I could not find one, so I am assuming no.

 

Second look at the crankshaft where the connecting rod meets, it looks like pretty ok. I think I am going to chance this one and see how it goes.

 

Thanks for that link Pete. I ordered parts already and will see how it turns out. Sounds like a strong engine, the 6.5 hp may be close enough in power.

 

Did the connecting rod bolts come loose and the piston hit the top of the head - unless you loosened that bolt that's the failure mode.
Like MM said above check the journal on the crank, if it catches your finger nail or other soft material....its pooched and time for Chinese knockoff replacement

 

I'm with the other guys but a bit late. No way I'd mess with that motor. The parts will be more than the HF 6.5 motor. They are worth 2x the $90 they cost!! Reliable 2-3 pulls to start. And if ur crank is scored its pointless.

 

The parts came in last week and I took the case apart. A better look at the crank does have some minor scoring. Can I just pull the crank and polish the journal with emery cloth to smooth it? I mean, can I get a little more use out of it before another failure?

I may be making a trip to the local TSC to see what they have. If I can get the motor that lines up right with the pulley on the end of the crank, then it may be the way to go. I am just concerned that there may be some alignment issues that may be a PITA. I will take some measurements. Do you just match up the current model engine to a replacementand it should line up?

Oh, and the pulley on the end of the crank fell off my bench and broke a chip off the edge. Argh.

Gotta get this squared away before the next sizable storm.

 

Should be pretty easy to mount a new motor. Might have to drill new mounting holes and possibly shim it...but that's usually easier than rebuilding a motor...

 

Hmm. Good point there. I will get the measurements and get to TSC. I have to see where the nearest HF is is nothing available.

 

I believe a new crank is 80.00 and change, plus the pulley. It is a toss up here as I already rebuilt the upper end. It is an easy engine to work on.

 

Yea motors are easy drill hole use washers or nuts for spacers.

HF has flat rate shipping often for $7. Which many times is cheaper than even driving to a local store. There even Honda clones on the bay I'm sure or amazon.

 

Return what u got eat the shipping and get a new motor

 

Buying that crank your too fat into a motor that potentially won't run as long as the HF model!! My buddy has one on his splitter. I think this is year 3 not a ton of hours but runs better than most Briggs motors and sips fuel. And starts 3rd pull. It it blew today I'd buy him another if I blew it and I'm sure he wouldbuy one if it blew on him.