reassemble Cub Cadet Challenger 700 - Crankshaft does not turn freely

[Jon V]

Good afternoon. When the timing chain came off its lower gear (previous owner had over-tightened the tensioner), I ordered new parts.. chain, oil-pump chain, tensioner etc.. But now that it's time to put it back together, the main crankshaft makes a clang noise and stops when you turn it by hand. I want to solve this before assembling everything. The camshaft cover is off so that the valves aren't being activated. Should the transmission be in neutral to turn the crankshaft? The engine was running fine until the chain came off the lower gear. Then it would spin when the starter motor engaged so I assumed the crankshaft was spinning. Any advice is appreciated.

[Joe Breaux]

I would pull the spark plug and see if piston is moving. You might have a broken rod  

[Joe Breaux]

It would be nice if op would come back and tell us what he found or how he solved it..could help others. 

[Jon V]

I appreciate your guidance here, and hope to get into the engine this weekend.. it's been a slow rolling project. If something internal is broken, I'll have to look at swapping in another one.

[Jon V]

UPDATE:

 Turning the ignition key to 'on' appears to move some solenoids in the transmission area. The crankshaft now rotates freely. I believe that the timing chain also may have been set incorrectly so that one of the valves was open when the piston was top dead center. I'm going to re-set the timing position of the camshaft with greater care and reassemble the motor - testing continually to ensure it's going to work.

[Jon V]

Major update.. the crankshaft drives the gear on the left. The oil pump drives the gear on the right. Instructions (the manual, YouTube videos etc..) simply state that the two gears need to be synchronized where the dot/dimples on each gear meet up as shown in this photo. However the crankshaft and oil pump have moving parts in the crankcase that will 'clash' if they aren't properly synchronized and it's more than just lining up the dots. Before installing the two gears shown in this photo, let the oil pump shaft find it's correct resting spot. whenever you turn it by hand, you'll notice it returns back to it's resting position. The dimple on the gear will be be towards the top. Now you can install the corresponding crankshaft gear with it's dimple also near the top. When the two gears are locked together in place, you can now turn the engine crankshaft by hand without any impedance or strange noises. You may have to count the number of teeth between the dimple and the contact point of the two gears to make sure the same number of teeth on both gears are offset equally. You may need to back off the crankshaft gear once or twice to adjust it so that the two dots come together exactly. This is why the engine did not turn when I followed the instructions and assembled it before.. the parts inside the crank case were not offset properly and were clashing together. I expect to have this engine fully reassembled by the weekend (still working full time here), and will post photos & results. Question for the group is - have you seen this additional guidance anywhere else? Do I need to explain it differently? 

[Joe Breaux]

Yeah, that would do it..good luck.hope it runs now.  These things were so poorly built, it's hit or miss if you get some miles out of them. Mine runs well now but it took some doing .

[Joe Breaux]

Good info for the rest of us..hope it works properly now

[Alien10]

Thanks for posting this info, it might save someone a very expensive engine failure.

Likely repair shops and manufacturer have a process and a tool that positions the gears such that it allows quick install and insures the correct synchronization.  For the rest of us, it is trial and error, just hoping the trials fix the errors before major damage can be done. 

Good work man.