My poor dad and his damn car problems.....

He had his van just die on him yesterday.took it to his friendly mechanic, figured out it was the crank pulley/balancer, whatever you want to call it.

one mechanic said "it's screwed, fill it full of JB Weld and sell it."

great advice...:<

I'm a pretty good DIY mechanic, seems to me that on most engines, there is a "keyed" timing sprocket that is sandwiched in between the pulley and the crankshaft...not too tough to replace if your skilled.
If the key itself has snapped or worn off, then replace the thing, right?

Or is there some sort of engineering fiasco I don't know about??

Any help is appreciated!!!!!!!!!!! thanks, Josh

 

This post may not elicit a lot of responses as others may be equally puzzled as to what your mechanic is referring to. Yes, there is a harmonic balancer but the reference to using JB Weld makes no sense in terms of a practical repair method. If he means the key has shorn off, then as you suggest, replacement is not that difficult. To my knowledge, this is the first reported case on this forum of a 4.0 shearing the balancer key. Given its rarity, perhaps another opinion is in order. Engines can just die from a lot of other reasons as well. If you provide some additional details perhaps that will generate a greater response.

 

I'll clarify....The van just died instantly, like that. Checked the fuel pump-ok. checked the t-belt\chain - ok.

Upon further inspection the original mechanic found the crank pulley to be slipping on it's own. (this is all info I got from pops over the phone)

Dad's mechanic called another mechanic, and he's the one who suggested the jbweld quick fix. I think its a ridiculous solution...pretty amatuer.

The same thing happened to my high-mileage Volvo,but it turned out the timing sprocket was just fine, it was the metal\rubber pressed pulley that has separated in itself. One trip to the old Volvo and 10 minutes later, I had a new\used pulley to install. Problem fixed! I was hoping that Ford used the same principle on their 4.0l engine,(having a keyed sprocket in between the pulley and crankshaft) and you just answered that for me...Thanks!

After searching all the Aerostar posts', I agree, I couldn't find one instance of the same problem. I'm looking at the van tonight, so I'll see whats really going on with my own eyes.

If the key is shorn on either end, it shouldn't be a big deal.I don't know where that other mechanic was going with the JB weld thing!?!?!

Thanks aerocolorado, I appreciate the help.

Josh

 

If the Key sheared you should be able to turn over the engine, but belt should't move.
Or if the rubber is out on in between, it might of been replaced and when they pulled it they didn't pull it from the center. If they pulled it from the outside then they could mess up the Balancer.

Jay

 

The crank pulley consists of two concentric layers. There is a thin layer of rubber sandwidched in between. What happened to your dad is that, over time, exposure to oil has caused the rubber layer to deteriorate to the point where the rubber could not hold the two concentric layers together anymore. The term for it is a "spun damper" which causes your timing to be off by a mile, and the engine won't start. Just get another damper and replace it. It's not such a big deal. The key is practically indestructible. When the mechanic says JB Weld, he meant to say you should just get rid of the rubber and epoxy the damper assembly together. That would be a very bad advice. The 4.0L uses a crankshaft position sensor, and the two parts have to be bonded at their exact original location for your timing to work. Moreover, I'm quite certain that your crankshaft will vibrate itself to extinction if you do that. It's better to get a used crankshaft from a junkyard. Even a new one wouldn't cost you that much. I paid $100 for a brand new one when the same thing happened to my Jeep.