Briggs and Stratton Crankshaft binding after installing new bearings and rod

[frisbeguy4]

I am rebuilding a Toro CCR3650 Briggs and Stratton 6.5 horsepower motor, the piston, rod, and connecting rod bearings were damaged by the motor running at a very high speed. I have installed the connecting rod bearings using white grease and attached it to the crankshaft. When I rotate the piston, it now appears to be binding in one location. I don't know where it is binding, as it should rotate smoothly. The crankshaft appears to be in good condition. I have not used any emery cloth to lightly sand it down. Does anyone have any thoughts? The crankshaft may have now a flat spot on it after the engine got damaged. I am considering on either purchasing a new short block, or just replacing the crankshaft. Thank you for your help!

 

[Rivets]

You are going to have to give us a little more info so we can better understand what you are talking about. We need model and serial number for your CCR. Also, model, type and code for the Briggs engine. Also, why was the unit disassembled in the first place? Also, what were the part numbers for the rod and bearings you installed?

 

[frisbeguy4]

You are going to have to give us a little more info so we can better understand what you are talking about. We need model and serial number for your CCR. Also, model, type and code for the Briggs engine. Also, why was the unit disassembled in the first place? Also, what were the part numbers for the rod and bearings you installed?

The engine is # 300-3466. The family is XL4XS.1415AA. The serial number of the Toro CCR 3650 is # 200011561. The Model Number of the Toro is 38445. The unit was disassembled as I left the engine running, when we had approximately 19" of snow, to find a newspaper buried in the snow. After several minutes of running faster and faster it made a lot metal sound and shut off. I took it apart and found metal shaving of the piston, connecting rod, and the connecting rod bearings or needle bearings. I carefully cleaned the cylinder , cylinder head and crankshaft. They appeared to be in good condition. I replaced the piston with a Briggs and Stratton #801279, the rings B & S#801280, and a connecting rod B & S #801277. I placed the needle bearing plates on the connecting rod and placed white lithium grease on the bearing plate to hold the bearings in place. I then placed the additional bearings on white grease that was earlier placed on the crankshaft. I then placed the bearing plate cover over the bearings and lastly placed the connecting rod cover plate on, and tightened the screws. I spun the piston and it was binding at one point. I am thinking that I either placed the bearing plate that is adjacent to the cover back words or the crank shaft was damaged. I am also wondering if I did not seat the bearing plates all the way. I put in about $160. I am determined to fix the motor and then give it to my son. I could buy a short block or buy either a good used crankshaft or new one. What do you think?

 

[frisbeguy4]

I am sorry, but some how on the left side column it state Cub Cadet. Maybe that is what I have for tractors.

 

[Rivets]

After reading you last post, two things come to mind, both have to do with the needle bearings. You did not replace the bearings, are you sure that you had all of them and that they were in good shape. You may be missing one, then the rest would cock in the race causing a pinching action. Second, because of the overreving and prop able overheating, one or more of them may have flatspotted, creating your problem. If it was me I would replace those bearings, part number 801290. You will have to tear it down, no matter how you wish to proceed, so you can check the crankshaft before making you decision.

 

[frisbeguy4]

Thank you for the reply. I received new needle bearings when I received the connecting rod. I installed all of the bearings accept 2 or 3. I did not want to over crowd them. I can try and add one more. It was difficult to install them, so I placed white lithium grease on the surfaces. I will try and add one more. Thank you for the suggestion. I did not think that if one is missing, the rod would bind! I wish I knew how many bearings are supposed to be installed. Do you have an idea?

 

[Rivets]

You need to get ALL of the needle bearings installed. Even one short will cause problems. This is one time you cannot take a short cut, patience will be your friend.

 

[frisbeguy4]

Okay, I wiill go and take it apart and try to add all of the bearings that came in the brown package from Briggs. I thought they gave me too many. I wish I new how many needs to be installed. It appeared full when I installed the ones I placed in the brackets.

 

[frisbeguy4]

Thank you very much for your help!! I went ahead and took it apart. I cleaned the crankshaft and applied white grease to it. I then took the needle bearings and placed them all around the crankshaft, placed the bearing holders on, connecting rod, then the cap or plate cover. I have two bearings left over, without doubling them up on the crankshaft. I tightened the screws and it rotates without binding. I do not know how tight the screws should be, as I tried tightening very tight,and the piston/rod assembly was hard to turn. I backed the screws just a hair and it appears to be working. Next I will place the rings on the piston and they will have the openings up to the ring stops found on the piston and place the piston back in the cylinder. I am almost home! I will let you know how it works out. :smile:

 

[Rivets]

Didn't have time last night to find this manual for you, but it may help if you have not gotten to far. You should have 32 needle bearings in between the rod and crank. Yes you need to get them all in there. Missing even one will shorten the life of your rebuild. This also contains your torque specs. Time to take it apart again.

https://lookup3.toro.com/request/gogetpub.cfm?vSvcDir=/manuals/&vPubNum=to_e_eng.pdf&vKey=43821878