Killed my Stroker Today

[YJason]

Not sure what happened but I got on it a little and it made a light poof sound and quit running. I then tried starting it and it sounded out of time, so I popped the dist cap and cranked it over and the rotor wasn't turning. At this point I believe I either broke the timing chain, cam, or sheared a key. The rotor was nice and tight with no backlash so I believe the cam gear on the dist is still good.

Anyone else have something like this happen?

[dwg86]

Pull your dist., and check your dist. gear.

[SilverXJ]

x2 I had that happen once. The cam position sensor/oil pump drive froze up and sheared the teeth off the cam sensor gear. However the cam was fine. New drive with gear and it was back on the road.

[Cheromaniac]

Not sure what happened but I got on it a little and it made a light poof sound and quit running. I then tried starting it and it sounded out of time, so I popped the dist cap and cranked it over and the rotor wasn't turning. At this point I believe I either broke the timing chain, cam, or sheared a key. The rotor was nice and tight with no backlash so I believe the cam gear on the dist is still good.

Sorry to hear that. If there's no slack in the rotor, it would indicate that the cam/distributor gears are good. It's most likely that the timing chain has either broken or skipped a few teeth on the cam/crank sprockets. Pull the timing cover, take a look, and let us know what you find. I just hope that the pistons haven't contacted the valves, otherwise you'll be pulling the head and replacing at least two bent valves as well.

[YJason]

I pulled the dist and the gear is good and the cam is not turning at all. While I was draining the anti-freeze I noticed that the v-belt is running 1 groove off the backside of the harmonic balancer pulley and the bolt holding the balancer on is tight. So it looks like I've got more problems than just the valvetrain . Looks like I'll be pulling the engine......again.

[SilverXJ]

Are you sure that the harmonic balance was fully seated against the crank/ crank gear when you installed it? How much of a gap do you have between the back of the balance and cover?

I wonder if it wasn't initially fully seated which allowed the crank gear to move which sheered the woodruf key

[YJason]

The best I can tell there is 9/32 - 19/64 (.281-.297) between the back of the balancer to the lip of the oil pan on the driverside inline with the pan bolt. I hope you can follow that and give me a comparison.

[YJason]

The balancer was seated correctly. Here is what I found wrong





I was under the impression Cloyes was a good brand name part? So what causes the crank gear to shear all its teeth?

[SilverXJ]

Wow.. I don't know... it looks like all the teeth just sheared off. Are you sire that it was on correctly (some only go on one direction)... maybe check the alignment with the cam gear.

I always take a measurement off the timing cover for clearance, not the oil pan. It is usually 1/8" or less... The only thing I can think is that the gear move so far forward that it went out of alingment with the cam gear and put most of teh force on the end of the teeth.. How is your thrust bearing?

[YJason]

At the time I took the measurement it was still completely together. Theres not much clearance between the cover and the balancer. The serp belt running off the the back of the balancer seem to be the result of an alingment issue with the new alt I just put on.

Thrust brg? not sure what your talking about?

[SilverXJ]

The thrust bearing is the third main bearing from the front of the engine with the sides on it.

Looks like this:


one other thought... rotate the crank so all the pistons are off TDC and see if the cam rotates freely...maybe something bound the cam up?

[YJason]

I didn't know if there is one behind the cam gear or not, but I thought that you were talking about the crank thrust brg. I let the machine shop assemble the engine so I'm not real familar with the internals of a jeep I6, just what I saw when I took it apart. I'm more of a SBC guy, I know thats probably a taboo word around here.

Yeah, I would think some thing would have had to be in a bind for it to shear all the teeth off. I'm going to vist the M.S. tomorrow and have a talk with the owner and see what he's going to do about it. I'll probably be pulling the engine tomorrow night and taking it to him and letting him figure out why it happened.

[SilverXJ]

There is no thrust bearing behind the cam on a 4.0L engine.

Let us know what he finds. I'd be interested in what caused it.

[YJason]

Is it worth going to a $140 double roller timing chain over a standard $60.00 timing chain? And what brand would you suggest? I've always thought Cloyes was the good stuff?

[SilverXJ]

I haven't had failures with any. I'm running the JP Performance adjustable billet unit. I can't report on any longevity on it...yet. I would definitely go with a double roller unit though. If your failure was actually the crank's gear fault I would call it a fluke.