dont_get_stuck

I just bought a very clean 2000 Jeep Cherokee today for 1000 dollars. The guy I got if from told me that it needed a motor because it was knocking. I have heard other cars knock, but the knocking coming from the jeep sounds like no other knocking Ive heard. It isn't the usual knock that is in rhythm. It seemed a little random. Before I even read anything on here about the flex plate problems I thought that it could possibly be something loose making a loud sound but I didn't want to get my hopes up. After reading about the flex plate problem and loose bolts in the plate being mistaken for rod knock, I couldn't help to get my hopes up. Im going to check the flex plate a soon as some of this snow melts.

My question is how common is the flex plate problem and are there any certain years that are more prone to the bolts backing out or the plate cracking?

It would be awesome if I got this jeep expecting to replace the motor and it turned out that it was only the flex plate.

Turbo X_J

If the bolts are not torqued properly the flex plate will crack no matter the year. Whats the oil pressure like do you have a mechanical gauge to check with? Have you noticed any coolant in the oil?

dont_get_stuck

What do the bolts have to be torqued to? No, I don't have a mechanical gauge and I haven't checked the oil yet but I will tomorrow.

bigjim350

The flex plate bolts, and bad cps sensors, are the two most common problems on an xj. IMO

Fsher21

look at some youtube videos of flexplate issues, and see if any of them sound like yours. I had the bolts on my flexplate loose, it was random rattling and clanking and sounded terrible. Tightened them up in 10 mins and the sound is gone now. Worth listening to a few vids while you wait for the snow to melt.

jeepkid46

mine was cracked all around the bolts just check it with a light and a pry bar the sound mine made was only at certain rpms

91_Cherokee

Glad to see this thread. Thanks!
I'm sure mine has this problem too. It's been knocking for almost a year now.

Willys55

FYI - The flex plate cracks because of a failed torque converter. The torque converter has to dissipate more than 90% of the heat from the fluid and during times of excessive stress or use it can reach temperatures that are too high for it to do this. The torque converter expands beyond its limits putting excessive pressure on the flex plate which over time cracks. To illustrate did you ever take a can of soda, crush it then take it in your hands and fold it back and forth? What happens? It cracks and if you continue you rip it in half.

bobvalli

Sorry to hijack, but.....

I suspect the flexplate is bad on my 98. When I looked at it through the inspection cover, the bolts seemed tight and I didn't see any hairline cracks yet still suspect somethings going on with it.

This is something for a tranny shop? How much would I expect to pay (ball park) to have a shop inspect and/or replace it?

TIA

winston427

I changed mine in my driveway. Paid 15 for a used flexplate at the junkyard and another 130 for a transmission jack (a very important tool when removing the trans). The local repair shop quoted me a price of $900 to change it. It took roughly 8 hours doing all by myself with basic handtools and an excessive amount of profanity. If you are not proficient in profanity yet..... you will be.

dont_get_stuck

Lmao. I owned a dsm. I speak profanity very fluently.

wildspear

I believe my flex plate is bad. When getting a trans jack what should I look for (weight cap, heigth, etc)? Pardone my bad spelling.

bobvalli

I'm pretty sure Harbor Freight sells an adapter for a regular floor jack. IIrc it was like $60.00. Pull the rotating cup off the the jack and screw the adapter down through the hole. Has adjustment ***** to cant the tranny front to back and side to side. The jack of course handles up and down.

4.0cherokee

Just fyi... I couldnt check my flexplate on my 99 because when you go to back the bolts out they hit the exhaust. I also checked an 01 and it was the same problem. Its not the big of a deal just unto at the manifold, and try and get some room that way. Just trying to give you a heads up just in case

bobvalli

I had the same problem on my 98. That's what makes me think I might have missed something while checking the plate. I thought about cutting the bolt and sliding the replacement in from back to front.