Hello NG,
I just bought a 1994 Chevy Suburban with a 5.7L. And what my problem is, is that a day after I purchased it, it started to make a constant knocking sound coming out behind the fan for the heater/ac. It only will knock when I start it and shut of the engine for about 30 seconds and then goes away. I reached down and found it to be coming from the re-circulation door is closing and making the noise. I told my wife and kids that there is a little troll trying to get out LOL. Anyways has anyone experienced this problem and how they fixed it.
Any input would be appreciated.
Thanx, Andrew