I am working on a Craftsman mower with a Briggs 6.5 hp engine. It's a model & type number 122T02-0854-E1. I am trying to assess the fesibility of repairing it I know that it has a bent crankshaft and it will need to be replaced. The guy I got the mower from says he kept running it after he bent the crank, it does vibrate and shake some...I have replaced a crank before on a similar Briggs.. I will replace this one seeing how the mower is one season old. But I don't want to throw good money after bad.

It does start and run, however it doesn't seem to run up to speed.
and it is using oil..smoke coming from the muffler. Spark plug is definitely getting oil fouled. I know I have the oil level right.

I need to check for a sheared flywheel key...I say that because I did get sort of a snap back when starting it. That said I am wondering if the
mower running out of time (flywheel key) could cause problem with the oil?

I checked the engine for compression with a checker and get 90-ish lbs after 3pulls so it doesn't sound like bad rings etc to me. Would running it with the bent crank have caused internal damage to the connecting rod...could it have shaken the oil breather loose? I have changed the oil twice within 20 minutes of running and each time the oil seemed to change to a battle ship grey color right away and maybe it looked a little agitated..like what happens with a milk shake?

Anyway what steps and in what order would you all recommend that I take to determine if this mower is worth fixing or just better to strip parts off of?
I want to decide if it's fixable... spending as little $$ as posible...don't mind taking the time...I just wouldn't want to fix the crank and then decide the cylinder is shot.

Any and all comments welcome

Spit

how does your air filter look? if it is oil fouled, I would suggest a new breather, if it is just plain dirty, get a new air filter because a clogged air filter will make a engine suck oil and burn it

BTW, your model number is not showing up on briggs website

Thanks for the reply... When I run the model number on Brigss Website I get a parts illustration for a model 122T00?

I pulled the blower housing and the flywheel key was sheared..I'd say it was between 45 to 60 degrees off...not sure how it was able to run that way but it did. I changed the key and ran it. It's still burning oil. Pulled the head and manually rotated the piston..it's leaving oil on the bottom of the cylinder on every rotation... I pushed on the head of the piston and it seemed sloppy (side to side and top to bottom movement) like there was too much play on the piston. I'm just a shade tree mechanic so I don't know for sure how much play should be there but it sure seemed excessive to me.

This mower was run with a bent crank & bent blade, and the blade was even mounted upside down for a while... so somebody tried to cut with the dull side of the blade while it was out of balance...is that a double whammy?

Is it possible that this engine being so out of balance for so long, caused a lot of wear on the cylinder and that's the reason that fresh oil changed color to battle ship grey so fast? Was the oil sump full of worn away aluminum from the cylinder or piston? It makes sense that the steel rings running against the softer aluminum at anything other that the correct angle could cause wear. I saw only a very light amount of scoring on the cylinder walls but the piston/rings seem to have way to much play, like the cylinder is worn.

Is there a spec somewhere for the diameter of the cylinder and or the piston? This engine is junk at this point but I'm learning by fooling with it.
and I'm curious as to what may have happened and why.

Again any ideas or comments welcome.

Spit

My suggestion would be ... STOP RUNNING THE MOTOR.... If you know it has a bad crank then replace it. The reason your burning oil is that the piston is most likely gouging up the cylinder wall and is letting oil by, if you keep running it you might as well trash it. A vibration in a mower isnt that safe either, it can tend to loosen up nuts and bolts i.e. the BLADE bolt so it is possible that that thing will throw the blade out from underneath it if it loosens up. The reason your getting snap back is also due to the increase and decrease of friction caused by the bent crank on the seals and the cylinder. My advise to you is pull it apart and check the cylinder wall, if its still smooth good if not buy another mower. If its ok get prices on a crank,gaskets,crank seals and a blade. The reason I say a blade to is because if this guy hit something hard enough to bend the crank, he hit that something with the blade first. Good Luck

I scrapped it out tonight...kept the blower housing & pull starter, carb and air cleaner, flywheel and the brake asby, wheels & height adjusters, transmisson & belt, gas tank etc. Considering how new this mower was it's a shame..but the front baffle on the deck had been knocked off making the deck worthless and with a bent crank and gouged cylinder the engine wasn't worth trying to fix. This mower belonged to a guy I work with and it's amazing to me that somebody could cause this much damage in such a short time.

I guess the vibration from a bent crank can cause the piston to run out of alignment and wear away the engine/cylinder walls.

Spit