Crankshaft keyway

[ClarkP]

I have a timing problem and have removed the front engine cover. I believe that I have located the problem but want to be sure. Does the gear on the crank have one or two keys on it? I believe that the key sheared. Unfortunately that is one tight gear to get off. Any suggestions??

 

[1stgen4evr]

I have experienced a sheared crank key on a Detroit. But it was caused by the blower locking up. Entirely different system from the cummins. Do you have some evidence of the gear shearing the key? Something locked up? I seriously doubt that has happened in normal service.



I have never had a gear off so can't say. I can ask at the shop tomorrow.



James

 

[JLEONARD]

I seriously doubt it has 2 keys. Try a gear puller. . sounds like it's all jammed up inside the gear bore.

 

[ClarkP]

With some more investigation, one can see that the key sheared. What happened in to cause this is only speculation, but fuel gauge was broke and ran out of fuel. With being an auto thought process is the torque converter locked up and stopped the motor with other parts still moving. Key was the weak point and sheared. Called some diesels techs at Cummins and they suggested what to do, and what they do, is put heat in between a set of teeth on the gear, take a chisel and BFH and hit it. This will either break it off or spread it enough to pull out. Put a new gear on. This sounded like a better option than yanking the crank to press it off. I had already tried binding the gears and spinning the crank back to attempt to remove the gear but that did not work. A puller does not fit betweent he gear and the engine case. So we will put the heat to it and see what happens. Will keep you updated on the situation.

 

[1stgen4evr]

If it is indeed sheared it would only be from something in the timing gear train that is locked, like the pump. Or the killer dowel pin fell into the mesh.



I would say you have just begun the fight. Let us know what the final solution is.



James

 

[MMiller]

I highly doubt anything behind the crank caused the problem. If that was the case we'd be shearing keys off everytime the engine was killed due to improper clutch release.



I'll bet something got into the gears, or the injection pump or vacumn pump is seized up.



At any rate, I don't know what it looks like in your truck, but... ... When we remove gears from Cat cranks, we will take a cutoff tool, and cut a groove down to the top of the keyway. Then take a chisel and drive it into the groove, this will finish the cut, and then spread the gear so it will come off the crank.



Before putting it together, make sure everything spins freely. After putting it together I would turn it over by hand to make sure everything still turns freely with no binding.



Michael

 

[Paychk]

From what I can see in Cummins QuickServe, there is a single key way and no key in the crank, just a dowel pin that fits up into the key way of the crank gear. Also the FSM states a heavy gear puller is used for removal; the gear is heated to 250° for no more than 15 minutes & driven in place.

 

[ClarkP]

OK, so I attacked this problem some more this weekend. It took a long time, patience, beer, and heat to finally remove the old crank gear. NOT PRETTY. Do not recommend this to any one. Since the entire front end is out of the beast, Go ahead and throw in new water pump? What is the part that sits at 12 oclock looking at the motor that has the fan and clutch attached to it? Back on track, I had marked timing with all gears, however I don't know how many times the crank spun within the crank gear after shearing the pin. It might sound silly but, How am I to get the timing back together, ie pump, cam, crank, and oil pump? I know there are timing marks on the crank "O" and the cam "O O" but where does the crank need to be before putting the gear on, etc.

 

[MMiller]

To make it easy, I'd think your going to have to pull the cam out, if you already have not. The new gear will have to be keyed to the crank, and then everything should time from that. Is the crank snout going to be ok? Or did it ruin the crank?



Michael