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Cracked Flexplate / Loose Flexplate bolts?

the noise is completly gone.
where is the CPS?
is this the same as flywheel position sensor?
thank you SO MUCH for your quick response!
I have a new one in my shed if your are speaking of the sensor on the top driver side of the bell housing.
Does it just bolt on, or is it adjustable?
Based on the notches cut out of the flexplate, I assume this is some type of optical or magnetic device.
My only true knowledge is based on 25 years as an electronics tech.
 
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Yes, he's referring to the crankshaft position sensor thats on the upper drivers, front edge of the bell housing. They might have forgotten to uphook it and yanked the wires or banged the face of the sensor against the new flexplate. Could be hanging against the exhaust as well (also check if the o2 sensor wire is against the exhaust). I would call the dealer and ask them what they messed up.

The 18163 bushing kit is the rubber bushings on the end of the sway bar.
352555.jpg



Overall, I'd say they padded the parts cost and labor by about 30%. But as you said, they had you by the ying-yang. On the bright side, I bet having an ET background saves you plenty of money elsewhere. People tend to give me their broken electrics and appliances. I fix the ones that don't need expensive parts (amazing how many are just dried up caps) and give them away.
 
thank you both.
I will see if I can find anything today.
Yea, I haven't had to buy a new TV for a long time.
And you are so right about caps drying out.
Between bad caps and bad solder joints, they make up 75%
of all repairs I do.
 
Oddly enough, a new replacement flexplate can cause your new symptoms. Years ago It took about 1 month for me to realize that my new aftermarket flexplate wobbled too much for the CPS to consistently get its signal. I tried 2 flexplates and finally had to go to PICK-N-PULL and get a USED FP to get the thing running!.
 
God I hope not. That's why I paid extra to have an OEM dealer install one.
I noticed today it happens around 2800 rpm.
If I really took the time, I could monitor the two CPS wires, plug a ac inverter into the cig lighter, and connect an oscilloscope while driving. Hell, I may just do that.
Regarding the CPS, I do have another friggin issue to deal with.
I reseated the plug, and was looking down into the area on the top when I noticed about 3 inches from the CPS the outer insulation has been torn, and the red wire's insulation as well. It appears that several strands have been lost, and it has been exposed to oxidation for quite some time. SO, that will have to be dealt with real soon.
 
I am so glad I found this forum.
As mentioned b4, the red wire lost connection totally (in my driveway).
My son and I took the CPS out, I repaired the connection, heat shrinked it, and got it back in i less than an hour. I was amazed for all the talk of difficulty, it really wasn't that bad. About 12 inches of extension, 12mm socket, and no need to even raise the vehicle. I did notch the upper bolt hole in the CPS to make that side easier to deal with.
It was also pinched between the intake and something else. If you reach around the top of the bell from the front side while underneath, you can feel the whole area quite well to guide things in/out.
 
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I took my rig to a well established trans. shop for a second opinion; the noise described in this thread was identical to the sound coming from my bellhousing.
TC bolts were loose & re-tightened, new fluid for $160 total. Like the Jeep dealer's tech diagnosis-- TC & tranny pump need replacement. Estimate ran as high as $1000+ for rebuild; High mileage on rig (138,000) has both shops balking at repair-- thinks I should "live w/ the sound of TC whine" & drive it 'till it dies"

WTF? 2 shops don't want this job? I'm at a loss & won't be paying for a third diagnosis at another shop. I want it fixed...

What's the general cost for new AW-4 w/ install just so I can laugh?

1997 XJ Sport
 
The install is around $400-500 if you provide the new tranny. At least that is what AAmco quoted me when I thought mine was bad. They are often on the for sale items people on this and other forums are getting rid of or parting out. They are not too scarce but I do not know if they are year specific. Mine is a Renix year and I think I had to have the one with the power/comfort switch. Not too sure.
 
I want to thank you guys for a wonderful thread that saved me hundreds of dollars in repair bills. I experienced the same symptoms described in this thread on my 1997 Jeep Cherokee. It is equipped with the 4.0L engine with automatic transmission and has about 115,000 miles.
I started noticing a noise that sounded like valve train rattle. I first suspected low oil, but the oil level was fine. After about two weeks, the noise grew louder. It was only present at idle, and it didn't matter if the car was in Drive or Park. The car ran fine, and the noise would disappear once I started moving. Every time I tried to trace the noise, it always lead me to the bell housing around the torque converter.
Today I put the car on ramps and removed the cover to the torque converter. I inspected the flexplate (what I've always called the flywheel) and found no cracks. I was about to put it back together, but I decided to check the Internet first and luckily found this post. It turned out that two of the four bolts securing the flexplate to the torque converter were loose. I tightened all four bolts, and the noise has disappeared.
There was one extremely valuable tip here. When tightening the bolts, the flexplate will rotate and keep you from applying sufficient torque to the bolts. Luckily, the ratchet head eventually runs into the oil pan, which stops the rotation and allows you to continue tightening the bolts. My Haynes book calls for 40 ft-lbs, but I just went ahead and tightened them to the max with my 3/8 ratchet (probably not recommended).
I was so inspired by this thread that I registered so I could post my experience. This seems to be a common problem in high mileage Jeeps, judging by the number of posts I've seen on the Internet related to these symptoms. I'm very fortunate that I didn't have a cracked flexplate, or something worse.
 
The proper convert-flexplate bolt torque is 55 ft-lbs.

For future reference, I recommend pulling each individual bolt, applying loc-tite, torque them all to 25 ftlbs first, then torque them all to 55 ftlbs (going in steps helps keep things from warping). If you plan to do any real work on your Jeep, I suggest finding a genuine Factory Service Manual. Haynes manuals are ok, but they frequently contain errors like incorrect torque values, showing steps out of order, or just bad plain bad drawings.
 
Congrats on getting the flexpalte tight again. Now you will know where to look if you hear the noise again.
Ditto on the FSM, it will save the money you pay for it time and time again.
 
I just wanted to post a thank you as well. My son and I both own xj's '88 & '95. This was the information that also saved me several dollars. We also found that 3 of the 4 bolts were only finger tight.
 
I'm going threw the same problem right now.

I purchased this 91 for $100.00 do to the fact it had the knock. I have had experience with the FP Bolts coming loose or the FP cracking at the crank bolts.

With the XJ running really well (the knocking never effected how the engine ran) I continued driving it every day for three months.

One day it started with the bad vibration and limped home. Next morning it started shimmied really bad, made an awful screech, and then stopped. Will crank over but not stop.

I've removed the inspection cover and the bolts to the TC are tight and no signs of cracks, but cranking the engine over reveled the FP moving a good 3/4 to 1'. Enough to slightly separate the bell housing from the engine block.

I haven't removed the trans yet to see the extent of the damage. The reason for the no start is due to the CPS being thrashed by the timing ring on the FP

I'm hoping for just the FP and CPS!

Mike
Methuen, MA
 
Finally had the chance to give it a good inspection and sure enough the FP is cracked all the way around the crank bolt location.

So now I'll have to drop the trans and swap out the FP.

This seems to be a common problem that happens. Has any one found an aftermarket FP that will stop this from happening, or is their a problem some where else that makes this happen.

Mike
Methuen, MA
 
I had the same thing happen with my 86 and it's 2.8 auto. The flexplate busted after knocking for quite awhile and I now have to replace it. Mine was actually caused by missing and loose bolts between the engine and transmission and I have a sneaking suspision that alot of these flexplate problems are caused by this. Well at least your 4.0 flexplate are easier to find then mine.
 
Maybe a stupid question, but I ask anyway. What can be the consequence of driving with a cracked flexplate? I suspect mine to be cracked, but can't afford to replace just now. Part-prices here are quite stiff compared to the US.
 
rsa42784, If you are still watching this topic, have you found anything new since the last time you adjusted those FP bolts? I believe I have a similar, if not the same problem and am just following up. I tightened all of my outer bolts (the four) and the knocking is still there. Not sure where to go from here, not ready to separate and pull the plate yet.
Thanks
 
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