I recently bought a non-running 88 F150 4X4 with a 5.0

The water pump pulley had come off the water pump, destroying the radiator. After getting a new radiator, fan, water pump the motor runs but it shakes like heck, and the crank or harmonic balancer appears to be bent (you can see it wobble). I even put on a new crank pulley to verify that it isn't the pulley that's bent. Even if the rubber part of the dampner was failing, the center wouldn't be bent. Any ideas? Is it possible to have a bent crankshaft?

The truck shakes so bad it feels like it has solid engine mounts!

One other note (maybe explains the shaking?).. the exhaust is split open at the O2 sensor and entrance to the first Cat... would that make it run bad?

Help me!!!!

 

First and foremost, you need to replace the balancer. See how much that helps, and go from there. If the crank was bent enought for you to see a wobble at the balancer, the bearings inside would be gone.



Take care,
~Chris

 

I have never bent a 5.0 crank, but my ex-wife broke one (don't ask). It still ran, but made a terrible banging sound and shook the whole car (84 1/2 Mustang GT350). It shattered the balancer, and when I tore it down I discovered the crank had broken at a counterweight, split the thing in two.

 

I will start with the harmonic balancer, though I can't imagine it is capable of shaking the entire truck! The outer ring looks like it's correctly seated.

If anyone has seen this happen before give me a heads up.

Thanks, Jon

 

It is new to me, but you could remove the harmonic balancer and briefly fire it up to see if the crank is moving around. If not, get a new balancer. Otherwise, you need a crank. And for the record, I have never heard of it happening, but I suppose it could... just not sure how. Unless someone jacked the truck up by the balancer or something...

 

Ok, so I pulled the Harmonic Balancer, and indeed someone had forced it over the key without correctly clocking it, cracking the balancer as it was forced over the key.

I fired it up and the crank appears to be straight, but it still has a bad vibration. Maybe a correctly clocked balancer would help? Anyway, I tried firing it once later this evening and the dang thing won't start! (cranks but doesn't fire up) Ahahahah what's next??!!!

 

Don't run it w/o the balancer. Get a new one, install it, and then figure out why it won't start.

 

You found your problem - now install a new balancer correctly. Life will be good again. As far as not starting - do the usual: does it have spark? Fuel? etc...

 

Son of a _____! It turns out it tossed the timing chain when I fired it up that time without the balancer on. I ended up selling the truck to a ford mechanic this weekend and he showed me that the dist was no longer turning while cranking the motor.

He has a spare motor so this isn't a big deal for him.

Thanks guys for your help..

 

Oh well. Live and learn.