2002 disco2, 4.0L

I noticed a whine begin in my engine about 1 month ago. It's gotten slowly worse the past few weeks. I noticed in the beginning that the whine stopped or decreased significantly when the AC clutch engaged and the whine returned when the AC clutch disengaged.

So, while trying to find the culprit I noticed a pinhole leak in the T-Joint coolant at the top front of the engine at the bleeder screw and noticed it had been leaking on the alternator, tension and idler pulleys on the right side, so I hoped one of those 3 were the culprit of the noise. I replaced those 2 pulleys, alternator and new hose+T kit. The whining noise is still there.

Does anyone have any recommendations on how I can better isolate the noise and conclude which device at the front of the engine is causing my headache? I don't want to keep throwing parts at the problem, getting very expensive.

 

i would systematically spray lube on each individual pulley/bearing, one by one. it should briefly alter/quite the whine/squeal if it is one of those.
then there is a stethoscope. is your truck sai?

 

Thanks for the quick reply Dusty.

Not SAI, sprayed pulley's already but it didn't make an difference in the noise. I assumed the bearing was still sealed on the side I was spraying or if it torns out to be the AC Compressor then it's likely got a couple of bearings in it.

I used a wooden 2x4 to try to listen with ear and device against opposite sides, couldn't find it. Will a stethoscope be any better than that?

 

Used a real stethoscope and I'm about 99% certain it's coming from the AC Compressor. I suppose my only question left is if someone can confirm that AC Compressors can make a whining noise and if so, is it the bearings and should I attempt to replace those bearings or order a new compressor?

I don't have a vacuum pump or the experience to replace it so should I just take it to a shop or will the tools and process be pretty easy?