I've used the ear/stick method for 20 years, so it literally never occurred to me buy a stethoscope.

 

It works.... Just saying..

 

100% by far the best $3.99 you'll ever spend on a tool > Mechanic's Stethoscope

 

Yep I actually have a super duper fancy pants one
It has interchangeable rods. Bent ones, hook shaped, all kinds of jazz.
It was almost $12.
But I use the Hf one most of the time.

 

I'm thinking it's the AC compressor. Since I'm new to these things and there is a british 4x4 repair shop near me who offered to diagnose and give me a full once over, so hopefully I'll have a solid answer this week, I'll update.
Perhaps this needs a new thread but:
I want to keep this disco forever and keep ahead of anything that might break and doing everything reasonable new with each repair. So, if I put in a new compressor, what else should I do? belt, tensioners, pulleys but what else? Is the water pump accessible to do while the belt is off?

 

One of the great things about this truck is the service manual is easily available.

land rover service factory manual RAVE download land rover resource, service manual, workshop factory manual, download, rave, vehicles including discovery, series, defender, range rover, freelander, LR3, Handbooks, Catalog, Catalogue, Land Rover Inte

It's called the RAVE.

I haven't done the water pump, but the RAVE will explain the procedure.

The compressor will likely need to be done by a shop anyway. Vacuuming the systems and getting the pressure right takes special gear and expertise helps. But I would buy a used one from Paul Grant.

 

Thanks for the info!
I come from the mindset of "Nothing needs to be done by a shop", but we will see how far that gets me! I'll likely do all the work but let a shop do a proper full recharge.

 

" I haven't done the water pump, but the RAVE will explain the procedure..."
It really is this easy> Land Rover Parts & Rover Accessories From Atlantic British | Discovery, Range Rover, LR3, LR2, Defender, Freelander and Land Rover Series Parts & Accessories

 

Also could be the power steering pump. IME, serp pulleys don't whine as often as they squeak or squeal when they're failing. My PS pump makes a pretty good whine and it's right there on that side by the A/C Compressor.
Just another possibility...

 

the ear-stick method showed the alternator to be the loudest. Lights flicker at idle sometimes and it's only charging at 12.6 volts, so that is a likely culprit.
So I'm planning to do: alternator, tensioner, 2 idlers, water pump, belt, upper and lower radiator hoses and thermostat. I think that should get me well ahead of the game.
Am I forgetting anything I should do proactively? In my best prices for all that only just around $500 shipped for all that, and a solid weekend day.