I just got done installing my MAC single cat headers. They installed great, but I'm hearing a noise that I haven't heard before, and I think it might be a leak.

Please help me figure out what it is.

First, I cannot hear it when the engine is just idling.

I only hear it when the engine is under load, like above 1/4 throttle in 2nd gear on up. I don't seem to hear it as much in 1st, but that's probably because there isn't as much load on the engine in 1st.

It sounds like phht, phht, phht, phht at the same rpm as the engine. It is not a ticking sound. It's a little softer than a tick. Again, I cannot hear it at idle or revving the engine in neutral.

I think it is a leak, but have no way to tell since the only time I hear it is when I'm driving.

ANY help would be greatly appreciated. Is there a good way to find an exhaust leak?

I don't feel down on power. Actually, it's quite the opposite, but I installed headers and catback so even with a leak, it would probably still feel stronger.

By the way, the MAC mids with single high-flow cat and Hooker catback sounds amazing. Louder than I thought it would, but a wonderful deep tone with no rasp. I think it's pretty intimidating actually.

Thanks in advance,
Dan

 

What you described, seems to be an exhaust leak.
Most likely at the collectors.

 

Is there a good way to check for leaks with the engine running?

I'm thinking of taking a few very thin strips of tissue paper and gluing them to the end of a long thin stick or rod of somekind and putting it near all the exhaust ports, slip tube or collectors. I'm wondering if I would see the strip of tissue paper move if I found the leak.

Dan

 

They might move just because of wind from other places, such as the alternator fan blade, or the fans, etc. With the pipes cold, stuff a wet rag in the exhaust pipes in order to create a little backpressure, you should hear it whistle at the leak.

You could also attempt seafoaming the car, but for me it was too hard to distinguish where the smoke was actually coming from.

I would also bet on collectors if its a soft pfft sound instead of a ticking.

And are you saying you can hear it with the windows down or from inside the cabin with the windows closed?

Try listening through some sort of pvc tubing if its hard to locate.

 

You can check for leaks easily if you have an air compressor. You take an air nossel attactment and tape it where it will blow air out of it. Then you stick it up your tail pipe and stuff a rag in around it to keep the air from leaking out. Next you hook your air hose to the air compressor. Now all you have to do is slide under the car; feel and listen for leaks. Since you do this with the car off you don't have to worry about burning your self.

Taylor

 

Thanks for the reply.

It's definatley not a straight tick. It is more of a pfft that gets louder the more I put the trottle down, but it's hard to hear how much louder it gets because the new exhaust is pretty loud now. It's fairly easy to hear when I put the throttle about 1/2 way in gear.

I can only hear it right now with the window down. I can't hear it with the windows up, or if I can, it's BARELY perceptable.

It's not going to do any harm putting wet rags in the exhaust tips? Do I stiff them real tight, or not.

Thanks.

Dan

 

I wouldn't do it this way, if an exhaust valve is open you blow all the crap from in the tailpipe straight in the cylinder. Not good.

 

Still wondering if there is any ill effect from placing wet rags in the exhaust tips, causing a lot of back pressure to hear the leak.

I suppose if the pressure was high enough, it would just push the rags out.

Any other suggestions?

Thanks,
Dan

 

I dont think your supposed to stuff them real tight, just enough to make a little backpressure.

I was getting that pffft noise before too and I tightened up the collector bolts when I threw on the catalytic today, and Its all gone.

Oh and btw it was a direct fit and went on with ease once I got those two bolts loosened up from the exhaust hanger.

 

heares an idea. stuff the tail pipes with rags, take off one of the air fittings going to the header and blow compressed air in it with a rag around it. then feel for leaks. just a thought

 

just got my mac mid's on sat w/ a low rest. cat and i have the same prob with the pfft over 1/2 gas also only with the window down how strange is that?gonna have a budy at the speed shop look at my work and see what he say's keep us posted with what u find out good luck

 

That's too weird. Hey, could you do me a big favor and shoot me a PM when you find out what it was causing the problem?

Good luck with finding it!

I'll keep updating this post if I find something.

Dan

 

John shot you a pm talk to you soon

 

it's dan sorry man. really late and spent