1978 Chevy Corvette loud noise & no power when accelera

CARMS1

MEMBER
1978 CHEVROLET CORVETTE
V8
2WD
AUTOMATIC
29,000 MILES

Please help! Mechanics have bleed me dry! Previous mechanic didnt put positrac additive in defferential and caused clutch pack damage. Found issue and put in additive but havnt replaced clutch pack. Previous noises around corners have gone(another mechanic replaced hub!) But now if I put my foot hard to the floor when taking off (in a straight line or corner) the car will make a loud grinding noise and have no power until I back off and take off slower, I believe if I put my foot to the floor while driving it will also ake this same noise and have no power(up hills etc makes it worse I believe. Or it requires more power and the chance the noise comes back is higher) the noise sounds like when my car scrapes the road on a high point. Horrible metal on metal crunching sound. I cant locate if its coming from front or rear. All new belts were recently placed on the vehicle and I believe they need tightening? Could they slip and cause this noise?
any help would be appreciated
thank you

1 Reply

MIKE H R

MECHANIC
3,094 POSTS

The belts would make a squeeling sound if loose. See if you can pinpoint the noise. Have a friend start the car and put it in drive, makes sure the brakes are on. Then step up the throttle and see if you can find any noise and where it is comming from. With lack of power I am thinking that there could be a problem with the catalitic converter. When they start going bad sometimes you will hear some rattling of metal or other internal parts at times. As the converter gets more clogged you will lose power beacuse of back pressure. I am not ruiing out the rear but rarely the rear does not cause that lose of power. You can also try having the back of the car off the ground and rotate the tires to see if you can hear any sound. Automotive stores have what looks like a doctors stethascope that runs a couple of dollars. With it you can hear what the insides of the rear or anyplace else is making noise.