There is a faint rattling noise coming from the front (belt side) of the engine. The noise just started yesterday, and ever since then, my boost gauge has only been reading 6psi at WOT. It always used to read 9-10 psi before. I just rebuilt the */C snout about 1000 miles ago, so I don't think it'* the bearings or the coupler. Any ideas?

Did you replace the coupler 1000 miles ago? Does the rattle sound like it'* coming form the top or the bottom of the motor?

I replaced the coupler at the same time as the rebuild. The rattle sound like it'* coming from the bottom of the engine.

Sounds like it'* your harmonic balancer. IF the rubbers cracked on it it can be like the noise you described. What do your belt tensioners look like? Can't really rule them out yet.

The tensioners look okay, just a little dirty. How easy is it to check the harmonic balancer out?

The only thing i can really think of is to look at the crank pulley while the car is running and see if the pulley is vibarating at all. But this wouldn't have anything to do with your low boost...I don't think.

I think a little bit of belt slip was involved in there somewhere. I repostion the */C belt and now I make a whole 7 psi. Maybe my BCS is starting to die.

The harmonic balancer looks fine, and I can't hear the rattle anymore. Could it have been the PS pump?

Thanks for trying to help out Lakeville.

Update:

I've replaced all of my worn out vacuum lines and checked the BCA, but my boost readings are still off. At 0% throttle the guage reads -10psi (it used to hover in the middle), and at WOT it goes to 3/4 on the guage and fluctuates by .5-1 psi, it used to peg itself between 9 and 10 psi.

Could this be bacause of a bad BCS? What'* the part # for it if it is? I can't find it anywhere online.