Help What if the crank is bent?

[WILL SHO U]

Ive been on here a few times about my Crankshsft Pulley (Harmonic Dampener) problem. It seperated about a weak ago and I was told if it wobbles at all, my crank could be bent.

I have a replacement pulley on the way and dont want to put all the work into changing it if the engine is trashed. Theres no knocking or wierd noises, just a lot of squeaks.

My question is, If the crank IS bent is the engine trashed? Could I fix it or should I start looking for a new SHO?

Any help would be great.


P.S Please no posts with "Your F'ed" I need serious information so dont waste your time.

 

[Ishodu]

I douth the crank is bent, its not that uncommon for the rubber to separate and the balancer to go south. Have you removed the old one yet? Was the bolt loose at all?

 

[WILL SHO U]

I have not removed the old one yet. I cant move it at all, but I know its impossible anyway. Feels real stiff. Just looks like it is wobbling, may not be. I know for a fact my Water Pump pulley is wobbling so that my be throwing me off.

 

[Bob Gervais]

Only way to tell is to get the old one off and have a look. The term "crank cancer" used to be valid, however it doesn't happen on its own. If the crank pulley bolt is not properly torqued (like with an impact gun) the pulley will wear the crank snout and cause issues. You're more likely to run into this than a bent crankshaft.

If that is your case, and the crank snout is worn, you do have a couple of options. You could remove the engine and replace the crank, or simply swap engines for one that doesn't have a messed up crank snout. If it were me, I'd swap engines. Much less work.

Replacing a crank pulley isn't exactly all that much work either.

 

[Storm-Chaser]

"Bending" a crankshalf is extremely rare, and usually only associated with a major engine failure at very high rpm or severe frontal-crash where the crank is actually hit.

I haven't kept-up on your threads, so I don't know who told you your crank might be bent. But in the absence of the two above scenarios, you're more likely to be hit by a meteorite than to have the crank bend for "other" reasons. If your mechanic is telling you this, go find a new mechanic.

The most probable reasons have already been stated - it's either the balancer or the key-way (a.k.a. crank cancer).

 

[WILL SHO U]

Ive read about crank cancer, but dont remember the specifics? Is it extremely hard to repair for someone whos never tore down an engine?

 

[yamahaSHO]

I fixed my old '92 SHO's crank cancer by installing a new key with some Loc-Tite and torqued the bolt down to 200 ft-lbs. 20k miles later, it's still running for the new owner. I put it to the test when I fixed it. Before selling, I took it up in the canyons for some hard running and then went to the drag strip and launched the crap out of the car several times. It held up so I felt it was good enough to sell and give my friend a "friendly warranty".

As far as the crank being bent, I doubt it. If it were bent, you'd need a rebuild and a good machine shop can straighten the crank for you.

 

[WILL SHO U]

Where would I be able to find a new key?

 

[Storm-Chaser]

Crank cancer is when the keyway for the harmonic balance becomes worn-out due to a number of reasons - but primarily either rust (leaking water pump over time) or improper balancer installation (vibration damage). Depending on how far the problem has progressed, it may or may not be "repairable" - that's largely dependent on whether the keyway that the harmonic balancer key sets into (that locks the balancer into place on the crankshaft), has been wormed-out so that the key would no longer hold in place.

SDPatt posted an excellent thread with pictures of his incident, and I believe Bizzy had a group-buy interest thread for having hardened crank keys made (like everything else, they're obsolete). But I was gone for several months and lost track of where the group-buy had progressed to (anyone else know?).

 

[Storm-Chaser]

Here's one example, of where the key wore to the point of shift out of the keyway:

Crank Cancer?
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... and one where the crankshaft keyway is excessively worn:

The SHO is a Crank Survivor
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