Recently got my exhaust done and ive noticed lately that if im in a drive through and I give it gas in gear I can hear what sounds like a pulsating sound under the truck even though the one single exhaust is pointing away from the wall of the drive through. Is this is just the exhaust hitting the y pipe and making that noise? I checked all the welds and see zero holes or cracks and its all new pipe. Just seems odd im hearing what sounds like air escaping but maybe its just the air inside the tubes bouncing off the wall. Would it make a noise like that? I checked twice for a leak and can't find any and the shop said there were no leaks and they always double check before they put it down off the rack

 

What engine do you have?
Have you checked the A.I.R. crossover pipe at the back of the heads? (if applicable)
They tend to leak at the ends, or the check valve in the middle.

Maybe you never heard it before because the old exhaust covered up the ticking sound?

 

If it's a 302 it could also be the EGR exhaust tube that is up underneath the intake manifold.

 

Its a 351. They took out the front cat and put in a magna flow Y pipe in its place and thats all they did. Its louder now and I didn't hear it before. There are like cross arms where the o2 sensor is located. What odd is it seems more pronounced and you can hear it when the truck is first started cold which its revving higher then too but from what I read it all said an exhaust leak would be heard more when the truck was warm bc the metal expands and would expose the hole or crack more. Ive stuck my head right down by the y pipe when its warm and cant hear anything spitting air but like I was saying if u are at a drive through and give it gas to take off it sounds like there is something leaking or spitting but im not 100 percent sure. Im beginning to think its the force of the exhaust hitting the Y and being forced from 2 pipes into one right there where the old cat was. Now that you guys got me thinking. Wonder if its the smog pump air thing? I didn't see anything hanging off but I wonder where that line is now

 

I think it was just the noise bouncing off the drive thru wall. Last night I stuck my head down there and listened real good and revved the motor up real good too w my hand on the gas petal and couldn't hear any ticking. I'll look closer when it warms up but it's ok for now. You can hear the exhaust gas hitting the Y pipe for sure. I think w the free flowing set up now it was just the pulses going into the Y I'm hearing bouncing off the wall. Truck sounds real good btw so that's a positive