1990 Suburban makes loud noise when in drive?

DAKNIGHTRIDER

MEMBER
1990 GMC C1500

1. 1990 GMC Suburban
2. 200k
3. Automatic Transmission
4. 2 wheel drive

When I put my car in Drive it starts to rattle a little bit then when I try to accelerate it gets very loud. WHen I put it back in park or neutral the car doesnt make the noise anymore. Then if I put it in reverse the car starts to make a rattling sound again. Once again as I accelrate its gets louder. What could be the problem?

1 Reply

DANIMALGMC

MEMBER
33 POSTS

You either have a bad U-Joint or some lose mounts.
With the vehicle in neutral and wheels blocked and emergency brake on, crawl under the vehicle. Grab the driveshaft and try to move it up, down, side to side. Basically any way you can. Don't be gentile, it should not move, rattle or shake. Try this at both ends (tranny and rear end). If it's a bad U-joint you will know. If there is no movement, it is probably your transmission mount, broken motor mount, broken shock, or even a broken spring on the rear.
Have someone look under (not get under) the vehicle when you put it into drive and look at the rear end, driveshaft, tranny. Just notice what is moving.

Good Luck