Thread: Crankshaft removal SBC

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Well, I have a problem here. I noticed the Harmonic balancer was wobbling when I started the car up the other day. Shut it down and grabbed hold of it. It was loose, so I put a socket on the nut and turned it and it moved without any pressure. I removed the front grill, radiator, belts, pulleys etc.etc........ The balancer unbolted easily and the keyway looks like the key sheared off and half is stuck in the balancer and the other in the crank. I can see two keyways clearly and the third looks like the other half of the key is sheared off and stuck there. (looking into the crank end from the front of engine it looks as if the crank had tree keyways) I need to remove the crank and haven't done this before. Can I remove the crank from below without taking the engine out of the car as I don't have and engine hoist ? The engine is a small block chevy.

No way on removing the crank in the car....3 keyways in the crank is kinda different, If that's the case(assuming the engine is internally balanced) I would use one of the good keyways to reinstall the balancer and scratch time the engine. I would also inspect that balancer to make sure it's not worn out inside,it should NOT have slid off the crank without a puller...

Do you have any history regarding the engine? A crank with three keyways is really strange.....there can be two separate keyways in line but, if there are three key slots cut around the crank, something is amiss. Also, breaking a key in shear (one half is still in the crank and the other is still in the balancer) is also an indication of problems greater than just a key...... a key is a mechanical fuse that breaks because of some greater problem

If your engine is hooked to an automatic transmission, you can probably remove the crank and ring gear combination if the oil pan can be removed. However, with the problems encountered so far, it would be wiser to pull the engine and find/fix everything. You can rent an engine hoist for peanuts.

Ouch - bummer..

A sheared key almost always causes enough damage to the crank that a new key won't help much. If this is a high performance engine, only option one is advisable. If, however; this is a cruiser that rarely see RPMs above 4 grand, you have two options: First (which is what you’re thinking) is to install a new crankshaft. This is time consuming and cannot be done easily with the engine in the car. It’s easier in the long run (trust me) to pull the engine, get an engine stand to allow you to rotate the engine with its bottom side up, and replace the crank. This also entails:
• New bearings for the crank and the rods
• New gaskets
• New rear main seal
• New front cover seal
• You may also need a new damper (in either case).

Option two is to drill a new hole for a steel dowel alongside the damper bolt that intersects the edge of the crank and is inside the diameter of the damper. This is tricky, but can be done successfully. Some diesel engines have this dowel in place in addition to the Woodruff key. The dowel is held securely beneath the damper bolt and washer which will allow removal of the damper in the future. For this option, you would need to clean up the crank slot and install a new key as close as possible to the original position. It can be held in place with JB Weld (literally) as it is for guide purposes only. It is helpful to have the engine timed at perfect TBC and set the new balancer at 10 degrees here. Then the dowel hole is drilled. A jig that has a center hole for the damper bolt and an offset hole for the dowel is essential for alignment of the drill and will securely clamp the damper in place before drilling.

That said – I would opt for the first option. I have performed option two one time on a 312 Ford that was in a big truck and at the time, I had no means to extract the engine because the truck sat too high for my hoist. It was freezing cold and raining at the time. With option two, we were able to get the truck into a garage (where it was dry and a space heater was available). Low RPM and the truck lived another good long life.

Good Luck,
Glenn

Some overlap on my previous post. I concur with the advice of Daffy and Robot - might be another problem that caused this whole mess. Underscores option 1 - remove the engine and check things out on a stand..

Daffy made the important point....if the balancer slid off the crank snout by hand (without a puller) something is SERIOUSLY wrong. Some nimrod may have sanded the crank or balancer diameter to make the balancer a slip fit.....sure would screw things up.

If the man is lucky..And in a perfect world, the bolt got loose and the key failed because the balancer was moving around.. In which case it could be salvagable.. I would certainly look at that option first..

Thanks for the input fellow rodders. I will, if need be, go with the total engine removal and check things after another set of eyes checks it out. I have all the paperwork and history on the engine itself. Thanks again for all the input.