It's a 98' 4.0l, auto & A/C. New WP and Alt this year as well. Started making noise yesterday upon start up. I took the belt off and the noise is gone. I spun all the pulleys and none grinding or difficult to spin. The A/C pulley sort of makes a scraping sound though. I put belt back on and noise returned around the Pass side of the engine. IDK if it could be A/C pulley, fan clutch, or the new Alt. Any ideas how to diagnose what is wrong?

 

Try spraying a little penetrating oil on the bearing on the ac pump behind the pulley and see if that helps it. At least it will tell you for sure if it is coming from the ac.

 

Get three or four foot pc of fuel line stick one end to ear take other end and search suspect area follow sound to issue...Old school Tech...

 

It sounds like it's coming from A/C pulley. What goes bad, the clutch or a bearing? My book doesn't address replacement. Would the comp have to be removed, are special tools required, and does system need to be evacuated/refilled? I'm trying to determine if I should farm this one out, thx!

 

Does it stop when acs engaged ?

 

No, I tried that first thing. The clutch does engage and disenegage no problem.

 

The noise does not stop .with ac on correct.

 

Correct, no change.

 

Id pull clutch hub check bearing be carefull dont loose any shims. Sounds like it might be compressor time to me.

 

Do a quick check on the idler pully. Mine made same noise, it was idler bearings. Might be quick fix?

 

Besides what has been said above, you gotta remember that the belts on our XJ's have to be really frickin' tight. But, if you can feel and hear noise from the A/C compressor, it is probably time for a replacement. Yes, the A/C system will have to be evacuated. You can take it to a shop and have them do it then do the work at home yourself. Then take it back and have them flush and fill it. I have filled several systems at home without a flush. I have only ever worked on A/C systems that were already empty because of a leak and have never released refrigerant into the environment. At least the old stuff you weren't supposed to, I don't know about the new stuff though.

 

I pickup up a bad pump with good pulley/clutch for free and it spins really smooth compared to mine. My crap is definitely confirmed bad now that I can compare it to a good one.