'93 Cherokee Loud Clicking / Knocking 4.0L

[johnson7634]

Hey guys,

I'm back again and wanted to see if anyone has run into the same issue I am having.

First, I recently install a used AW4 transmission (about 3 months ago) and haven't had any problems. Just the other day the Cherokee was vibrating very rough at low rpm and would smooth out when I accelerated. Well I changed the spark plugs, spark wires, cap, and rotor and the vibration continued for another week. Now the real problem is not the vibration as it went away completely but another problem came in its place.... a really loud clicking noise that seems to be coming from the bell housing area.

Now I want to venture out and say it is the timing chain (Jeep has over 225k miles) but is this something that goes bad? Also, I read online somewhere that the flywheel could be broken which could make a knocking / clicking noise. The noise is proportional to the rpm speed. I am going to take off the bell housing shroud tomorrow and inspect but wanted to see if anyone else had a similar problem. Any help is greatly appreciated.

[Cherokee 1993
4.0L in-line 6
225k + miles
fairly new transmission
clicking noise coming from bottom of engine or bell housing
Does not seem to be loosing power, runs great, starts just fine]

 

[SteelHeadz]

The timing chain does eventually wear out but it's failure rate on breaking is almost unheard of due to its chain design as opposed to a rubber/fiber timing belt. Overtime, the chain will also stretch from wear and the exessive slack will cause your engine performance and efficiency to suffer. The clicking noise could either be a cracked flexplate or a torque converter bolt loose and possibly hitting the inspection plate as it rotates. Look for any signs of crack on the flexplate towards the mounting flange of the crankshaft, thats where they would normally break. Look for signs of gouging or fresh marks of a piece of metal thats been rubbing around in the bell housing..That would be my first choice in diagnosing this concern.

 

[johnson7634]

Awesome. I'll take a look at these things today and report back.

I didn't think the chain would be the cause, but I just wanted to make sure with the experts. :shades:

 

[johnson7634]

Well the knocking was from loose flywheel bolts. I put some lock tight on them so they wouldn't come loose again.

I replaced the motor mounts at the same time when I tightened the bolts. The problem I'm having now is that the motor shakes (rather vibrates) at low idle speeds (around 1000 to 2000rpm). My dad said it might be the harmonic balancer. Has anyone had to replace one of these? What are some other reasons the motor could be shaking at low idle?

Thanks for the help.

 

[SteelHeadz]

possibly a mis-fire. I would say that the harmonic balancer is not likely unless otherwise falling apart( no offense to your Dad). Mis-fires are caused by multiple reasons. The possibilities are; Bad spark plugs, wire(s), compression, injector(s), lifter(s), Cam shaft lobe, rocker(s).. Since some of the mentioned possible causes are already been replaced, i would not completely rule it out but check it as a last verification in the process of elimination.