Ok so I bought this XJ yesterday. Beautiful truck. HIIIIIIH . Truck runs good. Drove it home 40 miles. However there is a violent sound coming from oil pan/flex plate area. Doesnt seem to effect HP or Engine functionality. It does NOT sound like rods(but not ruling it out)It comes and goes. Today I noticed it knocks particularly when fan cuts on. Also noticed there was no oil pressure. The seller says theres only 40xxx on this 4.0. He said his mechanic installed a high pressure oil pump. Could it possibly be lose or internally grinding possibly. I placed my hand on oil pan. Knock is not very far away. Any help would be GREATLY appriciated fellow Jeepers.

 

probably a cracked flexplate or loose bolts on it. The "no oil pressure" will more than likely be a bad oil pressure sending unit.

 

Seems like the flex plate is a little of balance. But the sound goes away for 15 seconds and the flex plate still has that wobble off balance look. Its weird. The fan coming on cant be coincidence right? Its not the fan of course but the 2nd phase in which the fan and other components cuts on? Idk..

 

I'm not too sure about the fan. but the noise your describing is the flex plate for sure.

 

Here ya go.

https://www.cherokeeforum.com/f51/ch...xplate-172081/

 

Ok. I discovered one bolt was missing in the flex plate. I reset the three bolts that were reachable on the flex plate and applied loctight.
Start was a little rough. (Always had start right up before). It eventually fired up then cut off within 10 seconds. Started again It seemed great. Let it run for 5 mins.. Giving gas ect. It ran good. Though I fixed it. Took it around the block and now the rattle is on the tranny side. Sounds awful. Fricking awful. Also have clucks when I put it in reverse and forward. ......
Cracked? Flex plate is the link between the two..

 

Going to get the forth bolt tomorrow. What's the correct torque? Is the torque critical for these bolts? Hoping I over tightened them rather then the being plate cracked.

 

Flexplate to Torque converter bolts -- 28ft/lbs

and to torque them properly you'll need an interchangeable head torque wrench with a 15mm end on it.

 

And nobody does it......

I'll bet the plate is already cracked.

 

oh i know this lol i have the torque wrench so when i get around to fixing my cracked flexplate i'll be torquing them.

 

Have fun getting it all up in there.

 

its a open ended torque wrench. with a interchangeable head on it.

looks like this




So i'll have no issue actually torquing them.

 

Maybe.

Ever think about this?

Perhaps the torque spec was wrong and that's a reason they loosened up?

 

that is quite possible, but i think it leans more towards the absence of a thread locker from the factory. Especially on a part that rotates the amount that the torque converter/flex plate does.

 

Except one thing:

There WAS threadlocker on there from the factory.........

I always have to wire wheel it off before reinstalling the LOOSE bolts with new threadlocker......