There is this "chirping" type noise that is coming from the passenger side exhaust and I can't figure out what could be causing it. It's on my '66 GS that I just purchased with the original 401. The previous owner had a 2.5" mandrel bent exhaust installed with what looks like Flowmaster Super 44's. All he told me is that it was Flowmaster. I call it a chirp because I am not sure how else to describe it. It's a chirp or a squeek type noise. It appears to be coming from inside the exhaust. At idle it is pretty faint but audible. When you drive down the street it gets louder along with the exhaust. I would say it's the mufflers, but I believe the noise is only coming from the passenger side. I can here it in the cabin when driving down the road and when I pass a wall or a guard rail I can hear it even louder as the sound bounces off whatever I am passing. My brother was driving behind me the other day and he said he could clearly hear it. I don't hear it coming from the engine compartment and have moved along under the car at idle and the sound is most prominent coming out of the exaust at the tip. It's not the tip vibrating, I put my foot on it to see if that changed it, but it didn't. I don't believe the heat riser is in place anymore so I have kinda ruled that out. Anyone experience anything like this before? Thanks in advance, Johnny
Sounds like You have a very tight system with a pin hole in one of the welds. I had a Nova with the same problem. When You find the hole a quick zap with a mig should fix the chirp:beer
Is it a "Chirp" or a "Whistle"? Chirp could be a clamp or hanger possibly vibrating due to exhaust resonance in the 1 pipe, or in the Muffler "Baffles". Whistle, could be from a small hole in the pipe, or a joint that may not have a full weld. What You stated about the "Sound" is exactly why I won't do another set of Flow Masters. I couldn't hear myself think if I was running in the Left lane on I-45 with my 72, even with an "H" pipe to balance the exhaust, & it didn't mater if I had the Headers or the Stock manifolds. BTW, My son is bringing the Shroud, Steering Box and other pieces off his 66 over, so you can take a look when you come for the rims. Give me a call. JR
Thanks guys. I will do some more looking around on the car to see if I can find something loose or maybe find that pin hole. If I can't find it I'll run it down to the local muffler shop I have used in the past and see if they can find it and fix it. JR - I'll give you a call sometime between 11am-1pm when I am able to get away from here for lunch to talk about the wheels and the letters for sure, and have a question about the shroud.
From my experience, a chirping noise can be made by a high pressure leak such as a head gasket leaking compression. If not leaking externally I guess it is possible to leak across between cylinders and show up in the exhaust pipe. I have not heard a chirp on gasoline engines but is common on diesels when the fire bead fails. This type leak is much more pronounced when throttled or put under load. To ascertain this, you may find it on a compression test showing up as adjacent cylinders a little low but is doubtful it would be out of spec due to the very small volume of loss. Better test would be to remove the plugs on that bank and air test each cylinder to the max available pressure and listen for leakage at the adjacent spark plug hole with a hose to your ear. Still, the pressure may not be enough to show up unless engine is under running conditions. TexasJohn
Its VERY VERY possible it is comming from the mufflers as you suspect. Years ago, when I had just installed Walker 17749 mufflers, I was getting a "popcorn sound" from my tail pipes, it sounded like ****, plus my tailpipes had the fiberglass sticking out of them from the inside of the mufflers. I replaced them under warranty with the same Walker mufflers, problem went away.
Johnny, you may also try removing one plug wire at a time on the offending bank to see it the chirp goes away.
Possibly an exhaust valve not closing all the way, like carbon on the seat, for example, or bent valve head. Did it "chirp" when you bought it?
Thanks for all the suggestions. Ill try to eliminate them one by one and see what happens. I didn't drive the car any distance when I first bought it so I don't recall the noise. Other than idling in the parking lot and getting loaded on the truck. But I do know it was there from the time it arrived home. Its been consistent since then.
