Hey guys I have a 99 cherokee with 225k miles and recently started hearing a knock from the bottom end. It started right after replacing RMS and oil pan unless I just didn't hear it before. Knock is constant at all Temps. Unplugged all injectors and noise stays the same. It increases with rpm until a certain point and fades off. Used a screwdriver and definitely sounds like it's more pronounced from the oil pan. Anything I can do or suggestions? I literally just put 4 new tires control arms and front suspension along with a tune up and insured and registered after being worked on for 3 months so kinda disapointed.

 

Is it a heavy sharp sound or more like a thud?How loud? And what do you mean by constant; does it sound like it’s happening every revolution?

 

Assuming the noise did start after the rms replacement.

1) with it running pull one plug wire at a time off the associated plug. (I know you did the injectors, but). If there's no change in the noise it's not an individual rod.

2) hook up a mechanical oil pressure gauge and see what it tells you... you haven't even mentioned what the oil pressure is doing

3) if it did start after the rms pretty obviously something got messed up during that job, you need to do some diagnostics including crawling under there with a stethoscope while it's running.... carefully

 

it's like someone is lightly tapping a hammer on something metal. Not a thud. I can faintly hear it from the cab with window down.

 

oil pressure drops to 20 at hot temp and goes up to 40 under load but that's with the dash gauge. I dont have a stephoscope however i used a screwdriver and the noise is most pronounced coming from oil pan. I'll try the spark plugs today and report back

 

If it sounds like someone lightly tapping on metal and it started after the rms my guess is that something got bent when you pulled the pan off...oil pump pickup, the bell housing dust shield....who knows, you're there, I'm not.
hopefully you got the bearing cap back on correctly.

 

yea it's more like someone tapping with a ballpeen hammer not a thud. It goes away after 2000rpm but maybe I just can't hear it. Inspection plate is off so I'm gonna check flywheel bolts. Main bearing was put on and torqued I did not torque girdle just snugged it down could it be that?

 

It wouldn’t hurt to double check for something simple like a loose or dangling part too. I had my radiator fan shroud get loose and for a while I couldn’t figure out what it was; it had me pretty worried. Then one day I finally noticed that if I moved the shroud all the clacking and tapping noise stopped. Obviously be careful and watch out for moving parts when it’s running

 

I wish it was that simple but it's definitely not a loose part it's engine related

 

If it were mine and:
1) I was convinced it was coming from inside the pan

2)I was convinced it started after I did the rms
I would be pulling the pan back off to see what's messed up before something breaks.

At this point I don't think the internet is going to help you

 

Check the torque convert bolts.