: 96 SLS knock

12-24-06, 05:23 PM
I'm looking at a 96 and the owner says he got an oil change and a week later it started knocking. "It does have a motor knock, doesn't miss or skip a beat but the knock is loud enough to not drive. I got an oil change in it last week and after 1 week the car started to make that noise." Could it be from carbon buildup? Would it show up that fast if it was carbon?

12-24-06, 05:39 PM
Carbon build up aka "Cold Carbon Rap" will go away within 60 seconds or so after starting. If it is continuous, it is not likely CCR. I have had CCR show up overnight on my '97 Deville. Quieted down before I got out of the driveway. A dose of WOT keept it from returning for a long time.

12-27-06, 02:07 PM
^^ Agree. After the engine is warm, carbon doesn't knock anymore. There was/is an Eldorado for sale near me with a knock, for cheap. I checked it out thinking it was carbon, but after driving for a few minutes, it didn't go away.

I think a fellow member had a knocking sound. But his problem ended up throwing a rod in his engine! :eek: