Heres a listing with photos of your compressor, oem DENSO.

2001 2002 DISCOVERY 2 II AC A/C COMPRESSOR OEM DENSO | eBay

This looks like a Denso 10PA17C, a lot of vehicles use DENSO, one may be Toyota Avalon (94 - 99). So you may be able to get the mystery bolt at hardware store (it'll be metric), indy AC shop, or a dealer with exploded diagrams in the parts department, parts dismantler, or the always fun trip to the u pull da partz salvage yard and automotive anatomy academy. Might be able to swap clutches, if that is what you determine is staying locked on. It is an electrically operated clutch, some later Rovers have a much different system, always go by the manual. You could probably swap clutch with unit in truck.

Suggest you unplug that rascal until you resolve. Once unplugged, AND not running, a few taps to the clutch area might break loose the rust/scale/corrosion/gunk and allow clutch to release.

Attached is sheet from RAVE, Rover must consider it a "module" to swap out.

Yes, you can do your work and take it to be gassed. Just don't run it until gas and oil installed. Not even for a few seconds.

 

FANTASTIC!! THANKS SAVANNAH BUZZ! I went to Autzone ( close to me ) an they had "engine design bolts" or something like that... replacement standard sizes... I picked up a 6mm x 1.0TP x 20mm and WOW! clutch has silenced by about 85% I sprayed a tiny bit of WD40 and tappity tap tap with end of wrench.. and screwed down as best I could... could not hold it still with hands but I think its pretty tight with 10mm socket... anyway.. WOW! now just a tiny baby hummm... engine smoothed out too!... now Ill unplug and see if clutch stops! but A/C still blowing nice and cold

 

You have screwed the Inscrutable, the always infamous magic missing dissolved in thin air bolt. Or you drove too close to the dealership and some of that warm hearted customer service made it melt.

 

hahaha yup! What a day of Celebration! lol at least now I can hear all the other pulleys in their own right! lol I think now I hear only the whine of a nice new belt! hehe now to address the window motor issue and mechenism ! window was propped up with a piece of wood and motor was locked up and slider wheels gone! I bought those snap in wheels and now to get a motor and BAM! door window working then to tackle the unlock mechanism ! on passenger door! manual unlock with door lever but power lock I can hear click but nothing happens... so will look into that repair! Engine always first!

 

So far she's not whining as much ... Maybe some damage occured... I just picked up a replacement compressor used from a land rover used parts aupier locally for 40$ ! Also some of the noise could be coming from the new gatorback Goodyear replacement belt??? Anyone used one of those? It has the splines on belt and also cross cut... Hmmm

 

That is called a "cog belt" in the HVAC trade, not sure about increased noise level, but they last a lot longer when used on systems with small pulleys, because they can take more flexing on small radius turns. If you turn off the AC and noise goes away it is the compressor, belt would still be turning...

 

well if I remember right, when I turn off a/c it gets louder and whinier... but I've been so happy with it not being as loud as before I was afraid to try it until new compressor arrives... lol its nice to enjoy my driving! lol

 

Nothing in Murphy's Law says that only one thing can be wrong at a time. When you have the belt off turn every pulley by hand for roughness, etc. Except that big one at the bottom. Also, while truck is running, you can hold a broom stick against your ear and place the other end on each device, like alternator, power steering pump, etc. and usually hear which one is making a lot more noise than all the others. Be careful NOT to snag moving belt with stick, fingers, or hair...

 

Well Hot dang! I unplugged the plug to compressor and ALL noise stopped! ( I just picked up a new compressor ( ebay ) with a 90 day warrantee from an A/C specialist for 25$! Im going to switch out the clutch! and if it doesn't fit ( different brand ) then Ill switch out compressor! BAM! DONE! I took my stethoscope and listened all over engine closely... no clicking or rattling inside engine anyplace! even though without it it sounds on left side of engine ( passengers side) a little potato potato potato sound, Im thinking exhaust leak because inside just a smooth wwiirrrrr.... just curious, why doesn't anyone suggest switching out compressor clutches instead of entire compressor? Am I missing something? I guess the factory compressor was a Sunden or something like that? I see many Denso compressors on ebay for my year (DiscoII models ).... maybe thats the reason? lol

[UPDATE] Im in luck! new 25$ compressor arrived with great feeling clutch! same part too! this way I don't have to open up system! also ordered a set of A/C gauges from harbor freight on sale for 37 bucks now! I haven't had a set in a few years since I moved so this will be a nice thing to have again even if only for one time use! lol

 

Another Update, I just found my dang lock ring pliers and got that ring off and pulley slid right off smooth as silk! ( new replacement pulley ). now in the AM Ill remove the whining one and should be good to go! :-)