Flexplate bolts / cracked flexplate noise - JeepForum.com

 
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post #1 of 14 Old 01-24-2008, 10:10 PM Thread Starter
Gsmyth75
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1992 XJ Cherokee 
 
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Flexplate bolts / cracked flexplate noise

I've had an apparent flexplate noise problem either loose bolts or a cracked flexplate, for a while now. And I was going to put it off till i try to build a stroker, but i heard from a guy that works at a tranny shop that theres an inspection cover that allows access to the flexplate bolts, and or will let you inspect the flexplate for cracks. Has anyone got any input as to how to remove the inspection cover? And are the bolts accessable from there if i keep bumping the starter? And has anyone tryed this?


1992 Cherokee Laredo 4.0 L6, Aw4, Dana 30/35, Np242, 201k
Crower p/n 44243 Camshaft, Camsaver High Oiler Lifters, He Pistons .030 Over, Decked Block and MIlled Cylinder Head. Melling High Volume Oil Pump
Flowmaster Super 40/ Cat and Tailpipe Delete, Apn Header, Homebrew Bored Throttle Body, Rustys Cold Air Intake with Spacer
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post #2 of 14 Old 01-24-2008, 10:22 PM
Offroadss350
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take the starter out the and turn the front of the crank with a breaker bar. tighten the bolts though the starter hole, a crack is going to be hard to see until you pull the trans.

'98 XJ Limited Stock
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post #3 of 14 Old 01-24-2008, 10:51 PM Thread Starter
Gsmyth75
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It more likely in anyones opinion for bolts to loosen to cause a clanking sound or for a flexplate to crack? Cause I've heard its hard to crack a flexplate, and I'm praying its just the bolts.

1992 Cherokee Laredo 4.0 L6, Aw4, Dana 30/35, Np242, 201k
Crower p/n 44243 Camshaft, Camsaver High Oiler Lifters, He Pistons .030 Over, Decked Block and MIlled Cylinder Head. Melling High Volume Oil Pump
Flowmaster Super 40/ Cat and Tailpipe Delete, Apn Header, Homebrew Bored Throttle Body, Rustys Cold Air Intake with Spacer
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post #4 of 14 Old 01-24-2008, 11:33 PM
peacekeeper
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I ran a cracked flew plate in my explorer for almost a year with no noise. The plate is easy to take off. Only 3 or 4 bolts. You can shine a flashlight on it while someone rotates the crank and see pretty much all of one side of the plate. I would check the bolts.
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post #5 of 14 Old 01-25-2008, 07:26 AM
AZ Jeff
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There are TWO sets of bolts on the flexplate:

1. the set that attaches the torque converter to the flexplate
2. the set that attaches the flexplate to the flange on the crankshaft

ONLY set #1 can be accessed by removing the flywheel inspection cover on the bellhousing.

Set #2 can be reached ONLY by removing the transmission.

There HAVE been some (relatively rare) reports of annular cracking of the flexplate around the bolt holes where it attaches to the crankshaft. It makes a knocking sound when this happens, and the only fix is a new flexplate.

AZ-Jeff
I don't own an XJ any longer, but I still think they are the best of all the Jeep products ever made. My XJ was my favorite vehicle in my 50+ years of driving.
So...I stick around and give advice.
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post #6 of 14 Old 01-25-2008, 07:42 PM Thread Starter
Gsmyth75
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Quote:
Originally Posted by AZ Jeff
There are TWO sets of bolts on the flexplate:

1. the set that attaches the torque converter to the flexplate
2. the set that attaches the flexplate to the flange on the crankshaft

ONLY set #1 can be accessed by removing the flywheel inspection cover on the bellhousing.

Set #2 can be reached ONLY by removing the transmission.

There HAVE been some (relatively rare) reports of annular cracking of the flexplate around the bolt holes where it attaches to the crankshaft. It makes a knocking sound when this happens, and the only fix is a new flexplate.
Thanks, I guess I can only hope its #1

1992 Cherokee Laredo 4.0 L6, Aw4, Dana 30/35, Np242, 201k
Crower p/n 44243 Camshaft, Camsaver High Oiler Lifters, He Pistons .030 Over, Decked Block and MIlled Cylinder Head. Melling High Volume Oil Pump
Flowmaster Super 40/ Cat and Tailpipe Delete, Apn Header, Homebrew Bored Throttle Body, Rustys Cold Air Intake with Spacer
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post #7 of 14 Old 01-25-2008, 08:52 PM
Tallpaul
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In the last two months I have ran across cracks in the flexplate around crankshaft bolts on 4.0 93 ZJ and lose flexplate to torque converter bolts on a 4.0 95 XJ.

Both had over 180K miles. I replaced both flexplates, the 93 due to the cracks and the 95 had slotted the flexplate to torque converter bolt holes.

Both sounded similar.
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post #8 of 14 Old 05-16-2011, 02:01 PM
KrugeJ
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can anyone tell me if the intermitant pinging noise coming from the bell housing area is a cracked flex plate?
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post #9 of 14 Old 05-16-2011, 02:54 PM
robsjeepxj
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I know of 3 guys in my local club who had cracked flexplates including myself. If you remove the 3 or 4 bolts holding the inspection cover off you can see the flexplate fairly well then. You may need to clean it really well with brake cleaner to see them unless they are really bad. Usually cracks are caused by loose trans bell housing to engine or torque converter to flexplate bolts. This causes the flexplate to twist instead of rotate. Here's a couple pics for reference.

This was mine, it make a loud knocking noise at idle that went away above 1500rpm. The marker is to outline all the different cracks.


This what happens if you ignore it way too long.
[/QUOTE]
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post #10 of 14 Old 05-16-2011, 02:58 PM
robsjeepxj
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Here's the other one from my friend Steves XJ



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post #11 of 14 Old 05-16-2011, 03:58 PM
bobvalli
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Quote:
Originally Posted by robsjeepxj View Post
Here's the other one from my friend Steves XJ
Thanks for the pics.

Do you know if any of the trucks that had the flexplate replaced had any vibration issues prior to the replacement?

I suspect the flexplate on my truck is either warped or cracked and am wondering if vibration is another symptom.

TIA
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post #12 of 14 Old 05-16-2011, 04:06 PM
robsjeepxj
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No I haven't heard of any vibration issues nor did I have any.
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post #13 of 14 Old 05-16-2011, 04:38 PM
bobvalli
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Quote:
Originally Posted by robsjeepxj View Post
No I haven't heard of any vibration issues nor did I have any.
Thanks

Not sounding too good for my theory about the plate.

This vibe has had me scratching my head as well as emptying my wallet since early last summer.
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post #14 of 14 Old 02-26-2012, 09:01 AM
tervalentpage
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Quote:
Originally Posted by bobvalli View Post
Thanks

Not sounding too good for my theory about the plate.

This vibe has had me scratching my head as well as emptying my wallet since early last summer.
It could be a combination of things as well. It could in fact be the flex plate, and something else minute like needing your tires balanced or a new ujoint or front end aligned or whatever else on top of that as well.
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