I have been given a Sears Craftsman 2 stage snow thrower 24 inch 177 cc engine. It is a model 247.889571 This machine was made for Sears by MTD and has a MTD Chinese made engine model 265SU. It has a broken connecting rod. It was run low on oil and the rod seized on the crankshaft. I can see that aluminum from the rod has fused itself to the crank journal. I think there is a term for this metal transfer. I am considering replacing the connecting rod and the crank if necessary. The rest of the engine and the snow thrower itself is s in great shape and seems to have been lightly used. The piston and cylinder show no scoring or discoloration at all. the rings are all in good shape loose and flexible so I think I have a chance to fix it. I have seen some videos of removing the aluminum using Muratic acid on the crank journal. is there anything that I should be aware of for this type of procedure?
I have replaced a couple of crankshaft on vertical lawnmower engines...this will be a first for me on a horizontal engine. Any and all I guidance is welcome
thank
CFS
Alan
#2
StarTech
Unless the crankshaft journals are scored just clean up the journals with Muriatic Acid. Note it produces strong toxic fumes so use outdoors with the wind to one side. Also rinse with water and oil immediately to prevent flash rusting.
Also make sure nothing is close in the area that can be damaged by the fumes. I had tools to rust down wind.
Thank you for the reply. Do you have a brand of acid or a concentration recomendation? Get it at Home Improvement store like Lowe’s or Home Depot
I am looking for technical info on the engine. Things like the torque specs on the crankcase bolts and a tightening pattern and the torque spec on the connecting rod bolts
Any ideas on where I could get service manuals for it. Thanks again
CFS
Muriatic Acid is the less pure commercial grade of HCl , suitable for a lot of process that can tollerate Iron impurities which is why it is pale green to yellow .
When purified it is colourless.
Std Muriatic acid is 35 wt%
Thank you. I picked some up at Hone Depot and used it the other day. I worked great in removing the aluminum that was fused onto the crank journal.
I am awaiting an order of wet-dry sandpaper from Amazon. The assortment I ordered has 200 to 1500 grit…8 grits at 200 or so at a step . Any recommendations on how fine of a grit I should start and finish with?
I finished the connecting rod replacement today. Happy to report that the engine fired on the 1st pull, running very smooth no smoke from the muffler. I am very grateful for the sage advice that I was given . It’s is a 24 inch 2 stage 177 cc MTD made Craftsman. Now that I have it running. I see that there seems to be excessive slop on the auger belt. When the unit is idling with the auger not engaged the belt is so loose it is slapping around. I did check the part number on the belt and it is the number that the owners manual calls for. I can see where it has worn a groove in the plastic belt cover. If I run it with the cover off (auger not engaged) the belt is jumping around and will rub against the discharge chute. I tried adjusting the cable but when I gave it tight enough to stop it from
hitting the base of the discharge chute the auger is engaged without the lever being engaged. It seems to me that some type of a belt guide near the engine pulley is missing would be logical. But I have a pdf of the owners manual and there is no such belt guide. Has anyone else had a similar issue? Am I missing something an adjustment or some problem that I am not recognizing?
The other thing is the engagement levers for both the auger and transmission are connected by a rod and there is some type of cam on that rod that is supposed to allow you to be able to lock the auger into the on position. Mine seems out if synch… is there a service manual or a video on adjusting this any help appreciated
