Thanks for all the help.

My dad disconnected what he thought was the secondary air pump below the battery. Weird thing is that it's still making the squeaky noise when it starts up -- although it seems to be quieter than it was before disconnecting the air pump. The car sounds a lot less "grumbly ...

Nearly forgot -- my 850 has about 186,000 miles on it. Trying to break that 200,000 mark!

So sorry I haven't gotten back to this! I took it to the mechanic, and he diagnosed it as a secondary air pump failure. He said that he'd heard that part make a ton of noise, but never one like that!

Hello,
The secondary air pump on my 1996 Volvo 850 is failing. It makes this awful screechy sound when it's on. I took it in to a reliable Volvo mechanic to get the sound diagnosed, and he said that the air pump below the battery was failing, that I could unplug it, and that I should be able to ...

Hello,
My 1996 Volvo 850 is making an awful screeching noise when I start the car. Over the summer, it made the screeching noise frequently (while the car was driving) when I was driving in the mountains, running the air conditioner, or on long road trips. We seemed to have to fill up the coolant a ...