Lunched 4.0 Motor? [with video!]
#16
Newbie
Thread Starter
Hey y'all,
Well... Good news! The motor is not destroyed. However, the distributor was.
I have since swapped that out and got her started and sounding as healthy as she was before. Had a peek inside the cylinders and ran a compression test and all seems well internally.
That said, she's still not running right, so it is still possible the timing chain may have jumped or something like that. Based on the fact she's now running rich as hell, I may have even jammed one or two of the injectors open. Still got a few electrical possibilities to investigate too.
So there you have it: the stock [albeit rebuilt and slightly bored out] motor can handle 7-grand for a second, but distributors (and possibly other electrical elements) cannot.
Going to index the distributor, re-check the entire ignition system and keep digging through the wiring in general, so I hopefully get her where I wanted her to be before all this self-inflicted drama unfolded.
Thanks again for your input, which put my mind at ease while I was trying to find time to get back under the hood.
Phew!
Well... Good news! The motor is not destroyed. However, the distributor was.
I have since swapped that out and got her started and sounding as healthy as she was before. Had a peek inside the cylinders and ran a compression test and all seems well internally.
That said, she's still not running right, so it is still possible the timing chain may have jumped or something like that. Based on the fact she's now running rich as hell, I may have even jammed one or two of the injectors open. Still got a few electrical possibilities to investigate too.
So there you have it: the stock [albeit rebuilt and slightly bored out] motor can handle 7-grand for a second, but distributors (and possibly other electrical elements) cannot.
Going to index the distributor, re-check the entire ignition system and keep digging through the wiring in general, so I hopefully get her where I wanted her to be before all this self-inflicted drama unfolded.
Thanks again for your input, which put my mind at ease while I was trying to find time to get back under the hood.
Phew!
Last edited by amanlikemike; 04-13-2021 at 08:00 AM.
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#17
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Join Date: Jul 2012
Location: Andover, VT
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Year: 1999
Model: Cherokee (XJ)
Engine: 4.0 L
Well, that was worth getting my headphones to listen to while I'm at work. I most certainly replayed the section between 4,250 rpm-full chooch over and over again
Glad to hear nothing too catastrophic went down. Those were some bad noises.
Glad to hear nothing too catastrophic went down. Those were some bad noises.
The following users liked this post:
amanlikemike (04-13-2021)
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amanlikemike (04-13-2021)
#19
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Year: 1996
Model: Cherokee (XJ)
Engine: 4.0
Glad it was the distributor
When you index the distributor, do it with the valve cover off.
If the crank mark is at "0" on compression, inspect the rocker arms on cylinder 1, you should be able to tell of the timing chain jumped.
If you still have problems, you may have over stretched the timing chain.
disclaimer: I am not a pro mechanic, I hang out under a shade tree....but I hope this helps...
When you index the distributor, do it with the valve cover off.
If the crank mark is at "0" on compression, inspect the rocker arms on cylinder 1, you should be able to tell of the timing chain jumped.
If you still have problems, you may have over stretched the timing chain.
disclaimer: I am not a pro mechanic, I hang out under a shade tree....but I hope this helps...
The following users liked this post:
amanlikemike (04-13-2021)
#20
Newbie
Thread Starter
Glad it was the distributor
When you index the distributor, do it with the valve cover off.
If the crank mark is at "0" on compression, inspect the rocker arms on cylinder 1, you should be able to tell of the timing chain jumped.
If you still have problems, you may have over stretched the timing chain.
disclaimer: I am not a pro mechanic, I hang out under a shade tree....but I hope this helps...
When you index the distributor, do it with the valve cover off.
If the crank mark is at "0" on compression, inspect the rocker arms on cylinder 1, you should be able to tell of the timing chain jumped.
If you still have problems, you may have over stretched the timing chain.
disclaimer: I am not a pro mechanic, I hang out under a shade tree....but I hope this helps...
#21
Newbie
Thread Starter
#22
Senior Member
Good to hear the news. Looks like my wishful thinking of the distributor was in the ball park. After I watched the video and heard the noise on decal that didn’t sound like something deep in the engine I felt it was more likely that it could have been the distributor. The no start symptom afterward was also a clue. What exactly did you find damaged in the distributor? Was the roll pin for gear to shaft intact? I don't know much about the consequences of this type of failure but it seems that it should not result in damage elsewhere in the engine.
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