This one has me stumped. I started hearing whining noises from the front of the motor recently and was guessing pulley bearings were shot. But as I was checking a cracked windshield washer hose (BTW those hoses only crack after a major snowfall & the roads are full of slush) I had the ignition on, motor not running and the hear a metallic whining noise coming from the front passenger side of the engine. Almost sounds like compressor noise. What's over there that could be the culprit? AC/fan was switched off. 2003 XJR 168k miles

Thanks!
Kevin
Milwaukee, WI

 

That side has the alternator and the idler pulley. You may have a bearing going out in one of them. Most likely idler pulley. You need to remove the belt and spin them by hand and feel how they turn. It should be smooth and effortless.

 

there are two electric pumps for the HVAC and SC .. I believe the HVAC fan is always running a bit when ignition on

 

And, with the ignition on, but engine not running, you will hear the fuel pump -- for a second or two -- pump fuel to the rails.

 

Today I just replaced my supercharger intercooler pump for the very same reason. Key on, engine off, temperature in the 30's (F), loud squeaking noise. The noise goes away when it's in the 40's (F) and above.

 

Sounds like it could be the SC pump then. Big job to replace?

I've attached a video where you can hear the noise.

Thanks

 

SC pump most likely. Shouldn't be too difficult of a job, remove the radiator fan shroud and you should be able to remove the pump and hoses then. It's on the passenger side between the radiator and engine - follow the intercooler hoses and you should be able to find it easily.

 

Kevin, have a look at the Bosch upgrade pump 0 392 022 010 this is the one I'd recommend.