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Unread 08-07-2013, 10:25 AM   #1
CherokeeMule
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Not just the typical 'Knocking Sound' Post

I lurk here and have gained so much valuable information in the past, but this one is stumping me a little bit. This is my 19th (not a typo) Jeep vehicle that I've owned from a '66 CJ5 V6 painted zebra-stripe to WJs. I buy them broken down and fix them up to drive and resell, then start again. Currently own: 02 WJ 4.0, 98 ZJ 5.2 lifted with np242 conversion, 97 XJ 4x4 4.0 Auto, and this new project.

Current issue is a '99 Chili Pepper Red XJ 4.0 Auto 4x4 I bought with the engine locked up. I pulled the engine out and found a replacement in a '98 ZJ that I personally cranked, ran, drove, removed the engine from, etc. I swapped all the components over and installed in the XJ. It has a knock from the converter/flexplate area that sounds like the typical type rod knock sound. I have torqued the plate to crank bolts, rechecked the plate to TC bolts, and removed the engine again to figure it out. I don't see any cracks, the holes don't seem wallowed out, no obvious interference with starter, etc.

Can the torque converter become damaged by the sudden (I suppose) seizure of the engine? Can they produce the same type noise as described? I also put the bolts back into their respective holes in the converter and ran them down with a ratchet. A couple of them appear to bottom out against the TC before they would clamp against the flexplate. In other words they almost look like they are a thread or two too long. Anybody ever put lock washers on these bolts? I think there'd be room for them.

Thanks for your thoughts and replies in advance,
Dan

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Unread 08-08-2013, 08:24 AM   #2
gs69350
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I had an XJ with a flexplate knock. I thought it was a rod at first and ended up getting rid of the vehicle. (shoulda kept!)

Anways, the XJ has AW4 trans and the donor ZJ had 42RE. I have NO idea if the flexplates are different, but it could be your problem. A place to start.

I've never seen lock washers on TC bolts, I wouldn't recommend it, this is a critical part of the drivetrain and although washers may "fix" the issue, it is not the correct way and can have consequences down the road.
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Unread 08-08-2013, 09:22 AM   #3
CCKen
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Do you have the original factory bolts or some hardware store bolts?

The threaded portion of the original bolts should be 14 MM from under the head to the end of the threaded portion.

Original bolts:

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Unread 08-08-2013, 09:26 AM   #4
96_Cherokee
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I believe so ill have to get under it on my next day off and ill let you know
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Unread 08-09-2013, 07:30 AM   #5
CherokeeMule
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Quote:
Originally Posted by gs69350 View Post
Anways, the XJ has AW4 trans and the donor ZJ had 42RE. I have NO idea if the flexplates are different, but it could be your problem. A place to start.
.
I did switch to the '99 XJ flexplate, there are differences in them and I'm pretty sure there's no way they'll interchange. They'd bolt to the crank, but the TC holes/bolts are different size.
Thanks for the suggestion, though!
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Unread 08-09-2013, 07:37 AM   #6
CherokeeMule
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Quote:
Originally Posted by CCKen View Post
Do you have the original factory bolts or some hardware store bolts?

The threaded portion of the original bolts should be 14 MM from under the head to the end of the threaded portion.

Original bolts:

I'll have to measure the depth of the thread, but they look just like that pic. Same head pattern, etc. When I try the bolts in differnt holes in the TC some won't go all the way down using a ratchet to tighten with. They leave enough room that if you were under it with a wrench there's a possibility they would not clamp all the way down onto the Flexplate before 'bottoming' out. I'm convinced the 'plate is good, so I'm going to change the converter (it seems to have excessive movement/rattle in it just moving it around on the bench) and try again. I'll post back results.
Thanks,
Dan
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Unread 08-09-2013, 08:41 AM   #7
bigbill888
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My vote: try the washers. Post if it works. Maybe that's why most 4.0s have that little knock.
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Unread 08-09-2013, 09:00 AM   #8
CCKen
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Quote:
Originally Posted by CherokeeMule View Post
I'll have to measure the depth of the thread, but they look just like that pic. Same head pattern, etc. When I try the bolts in differnt holes in the TC some won't go all the way down using a ratchet to tighten with. They leave enough room that if you were under it with a wrench there's a possibility they would not clamp all the way down onto the Flexplate before 'bottoming' out. I'm convinced the 'plate is good, so I'm going to change the converter (it seems to have excessive movement/rattle in it just moving it around on the bench) and try again. I'll post back results.
Thanks,
Dan
Good idea. The TC may have been damaged in that sudden stoppage.

If you're going to the trouble of replacing the TC, you may want to consider replacing the trans oil pump seal while you're at it. OEM P/N 83503752.
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Unread 08-09-2013, 12:01 PM   #9
CherokeeMule
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Quote:
Originally Posted by bigbill888 View Post
My vote: try the washers. Post if it works. Maybe that's why most 4.0s have that little knock.
Good point!
I ALWAYS blue loctite 'em, but this time I'm buying brand new bolts (factory kind) and putting on at least those little star-shaped locking washers in addition to the loctite.
Some of the bolt threads look kinda 'flat' like the holes in the TC needed to be chased with a tap.
I'm going to look at that very closely on the reman TC I'm getting from Advance Auto parts and definitely try all the bolts in all the holes before installation.
I'll try to get some pics of all this and add them to the thread.
Dan
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Unread 08-16-2013, 08:40 AM   #10
CherokeeMule
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Quote:
Originally Posted by CCKen View Post
Good idea. The TC may have been damaged in that sudden stoppage.

If you're going to the trouble of replacing the TC, you may want to consider replacing the trans oil pump seal while you're at it. OEM P/N 83503752.
Yes. I ALWAYS change that front seal as a matter of practice. Just too hard to get to even if it wasn't leaking before!
Quote:
Originally Posted by bigbill888 View Post
My vote: try the washers. Post if it works. Maybe that's why most 4.0s have that little knock.
I got a DACCO converter ($150 exchange for mine) and right out of the box my bolts (I had chased the threads with a die) screwed right down flush with no resistance or even a wrench required. I blue loctited them and also added some star-shaped locking washers I got from the hardware store. I have it installed and everything but those darn top two bell bolts to see if the noise is gone. Got too late last night to try it, so I'll post back after I fire it up. I noticed this time that the lower starter bolt (don't know if it was the right one) bottomed out in it's hole before clamping down on the starter ear. If that was the whole problem (allowing it to knock) I would be upset. Thankfully I may never really know! I put a washer on it and it tightened up. Geez.
Dan
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Unread 08-16-2013, 03:17 PM   #11
CherokeeMule
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Got everything (minimum anyway) hooked up and cranked it.
No change. Same knock. Sounds just like a bad rod knock so I am on to more diagnosis.
I'll get another set of experienced ears to listen to it.
I just don't know how anything could have happened to the engine from pulling it out of the ZJ that I listened to it run in, to transporting it to my house and putting it in the XJ. I pulled it myself so there was no switcherooo or anything that could have happened.
Weird!
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Unread 08-16-2013, 04:19 PM   #12
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Use a stethoscope to try and pinpoint the arear where the noise is coming from. Itll give you the best indication as to what the cause might be.
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Unread 08-17-2013, 11:08 AM   #13
CherokeeMule
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Originally Posted by psychoteen101 View Post
Use a stethoscope to try and pinpoint the arear where the noise is coming from. Itll give you the best indication as to what the cause might be.
I guess I'll have to invest in one. I've been using a long 17" extension pressed up to my ear. This is really baffling. I pulled the valve cover and plugs and turned the engine over and over with the crank bolt. I know I probably wouldn't be able to diagnose a rod bearing or wrist pin like that, but I didn't sense anything broken. It turns smooth with no binding or squeaking. I don't know, I'm open to any suggestions.
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Unread 08-17-2013, 12:52 PM   #14
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pull the oil pan?
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Unread 08-17-2013, 01:33 PM   #15
CherokeeMule
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Originally Posted by xjdantheman View Post
pull the oil pan?
Yeah, I guess that's next. I've been going over it and over it since it was a zj engine to see if some of the stuff I had to switch off the xj could be suspect. I used the xj intake, zj exhaust since it wasn't cracked like the xj. xj flexplate since the zj is different. xj backing plate (behind engine).
Next thing is to remove the torque converter bolts and push it back from the flexplate and crank it up like that again just to see what happens.
I'll pull it back out and double check everything again, then pull the oil pan while it's on the hoist.
I did crank it up and pull the plug wires off one at a time to see if any of them affected the noise. No affect at all except creating the obvious miss.
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