Hello, I have a 69 Chevelle Malibu with the original 307 engine. It had headers on it that my dad had put on quite a few years ago. They had a few holes in them and were pretty worn out. When I replaced them I chose to put stock exhaust manifolds back on. Mostly due in part to easier accessibility to oil filter and spark plugs etc My mufflers were also pretty shot. A friend of mine gave me a set of glass packs to put on it. It sounds really good except for one thing. There's a loud "undercurrent" sound that is making me CRAZY! It's not really loud when I first start it but it gets louder as the engine warms up. It's kind of a clackety/bangy kind of noise. Almost sounds like a double head hammer being banged back and forth between two pieces of thick metal. I have double and triple checked the ALL the welds. They're good except for one small pin-hole on the drivers side, however i'm reasonably certain that that is not my problem. The flexplate was replaced about 2 yrs ago because the tranny bolts had somehow come loose and the tranny was slipping back and apparently caused the flexplate to crack. The guys at the shop said it came off in two pieces. Seeing as how they were the ones who noticed that the tranny bolts were loose, I am somewhat confident that they tightened it properly. So I don't think it's the flexplate again (i could be wrong, idk?) I know a couple "home mechanics" that I believe "know their stuff", however for some reason they can neither one hear it. I've used a stethoscope on the block and tried the old "cut a wooden broom handle off and hold one end to the engine block and the other end to your ear " trick (does that really work in your opinion?) And didn't hear any crunchy, clackity, bangy, grindy, thumpy or tickety sounds. It actually sounded surprisingly smooth for it's age and mileage. So next I used the stethoscope and went along the length of the pipes. I could definitely hear it but still couldn't tell exactly where it is coming from. The sound does NOT stop when I stop the car so i'm sure it's not something that's on/in the drive train. So I'm wondering, is that the way glass packs are supposed to sound? I've never had a pair so I don't know how they're supposed to sound. Do glass packs "go bad" inside and if so how can you tell? Thank you for your time and opinion! Vikki
have the same problem?
Monday, March 17th, 2014 AT 8:51 PM