My Old IROC has developed a knock at idle and low RPM that sounds just like a rod knock and being the original engine, I was expecting the worse. I had some free time after work this evening and went out to see if I could determine what the knock is; I pulled each accessory belt one at a time and ran it to see if the knock went away. I found that when I pulled the power steering pump belt off the knock is gone, it's just a tad low of fluid but nothing extreme, so I'll pick up some power steering fluid tomorrow and see if I can get it to quiet down; may have to change it out. I've never seen a pump make this knock before; any of you guys seen this before?

 

UPDATE: This morning I went back out and serviced the pump back up and did a little more troubleshooting. I found that regardless of which belt I put back on alone, the knock would return and after a little head scratching, I found the crank pulley bolts loose. Torqued those back up and all is good again.

 

Nice work

 

Can't say I've ever heard of a PS pump making "knocking" noises before. It's probably the bolts on your crank pulley that came a little loose.