My brother is JulietZ28, and he thinks he has a leak in his Hooker Super Comp long tubes. On the driver side 1st cylinder primary, where it is split in two. He thinks that this small exhaust leak, if it is that, is letting air in/exhaust out. I say that the exhaust has such momentum that It can't do a 180 and squeze out the tiny whole. But there is a tick/rasp comming from that side of the headers. But when you hold a flat head screwdriver between the header and the heat sheild that is right next to it it won't make the sound. He also says that it doesn't make the sound after being warm for awhile, but will when he comes to a stop sign or light. He thinks that the metal gets hot and expands, closing the gap. But that wouldn't explain it comming back at a stop. I say it is just rattling against something. He also thinks that if it is an exhaust leak, that the 02 that is getting in is hitting his 02 sensors, and increasing the fuel mixture. I say that the 02 that is getting in is so minute that the increased fuel mixture is so little it wont make a difference. Let me know what you guys think of who is right/wrong and either way I'm faster.

At the light
Him/Me
/
At the end of the 1/4
/

 

It is possible to have an exhaust leak there, however, it will not let air in. Air won't leak into a high pressure area from a low pressure area. That would be like a garden hose with a pin hole sucking air in when you turn on the water, just not going to happen.

The exhaust gas escaping could throw off the O2 sensor on that side slightly. It could give it a false lean since there is less gas passing by the O2 sensor than without a leak. The ticking could also theoritically cause knock retard.

I bet your pontiac mill doesn't get 25+ MPG on the highway. LOL, but nothing runs like a old Poncho!!!

Scott

 

Also, look for black carbon build up around that joint. If it is leaking, it won't take long to make the area back and dirty.

Scott

 

lol he gets horrible gas milage with a 400, 4.10 gears, and a 5-speed talk about highway hell!

 

you forgot my new fuel leak mod lol. The things we sacrifice for ungodly amounts of torque. But I can do 60 mph @ about 2500-3000 RPM...in 5th. He may have good milliage, but I'm louder, deeper, and sound like the armageddon on wheels

 

Basically he's right, you're wrong.

Trust me, that slip joint can and will leak. Also the garden hose analogy is inaccurate. The exhaust does not flow though the primary in a constant stream the way water flows though a hose. It pulses as the exhaust valve opens and closes which causes periods of high and low pressure allowing outside air in. This will throw off the PCM because its no longer getting an accurate A/F ratio from the O2 sensors.

 

I can see what you mean about the exhaust not being constant, but I don't see how that would make the tick/rasp sound, that would stop when you pushed the primary with a flathead.

 

No offense but you obviously havent heard many exhaust leaks. They almost always tick to some degree, its almost a metallic sound (suprisingly). The fact that the noise stops after it heats up further supports my arguement. If the headers were rattleing against something why would it stop after it warmed up?

Anyways if it stops when you apply pressure you're either 1. Changing the alignment of the parts just enough to so it stops leaking or 2. The part you're applying pressure to is actually rattleing a little and the pressure stops it.

In my case it was #2. The #1 primary tube (Hooker LT's) was really loose so it rattled like crazy AND it leaked. So I had a rattle to go along with my ticking noise. POS's....

 

Basically, any leak will affect your O2 readings. It is counterintuitive, but the moving stream of exhaust is actually a low pressure area when compared to the ambient air. Oxygen from the atmosphere will get in and mess up your mixture. Fix the leak and it will probably fix your problem.

 

Actualy I had 2 huge exhaust leaks for the longest time, but they sounded like low picthed rasp, rather than his high pitched tick. You've made some good points, but It doesn't answere all the questions. Like why it comes back at lights or stops even after it's warmed up, and why it doesn't do it when it's first started, wich an exhaust leak most likely would do. One of the main reasons I didn't think it was a leak is because it wasn't consistant like leaks usually are.

 

The smaller the leak, the higher pitch of the "tick".

 

You probably have a consistent hole, it just leaks at different rates depending upon the velocity of the gas flow, the gas temperature and the pipe skin temperature. Each of those variables is highly dynamic and if the hole is small, will change the apparent acoustics with the operating conditions. The symptoms you describe point more strongly to a small hole.

 

So it looks pretty obvious that i have an exhaust leak at the infamous slip-fit primary have any of u found a way to fix this? Im dreading pulling those headers out again What do you guys suggest?

 

lol again, you never did it in the first place. But if you do have a leak which I am still skeptical of, Im sure there is a way to fix it with them in the car.