Engine Exhaust leak robbing power.

Try cutting of the joint where you had it welded and use a flange, this should help make it fit better and not leak. Welding it together might not be a great solution to make the Forza header work..

A friend of jcrwzr mentioned that he used teflon tape before to seal exhaust leaks. I did some research and other people use it too. I'm amazed that it doesn't melt or burn. Will this work as well?
http://en.wikipedia.org/wiki/Polytetrafluoroethylene
According to the info on there, it has a melting point of 327 degrees C. How hot does the header/pipe get down there?

Exhaust leak robbing power.

As some of you know, since the Forza header, the exhaust leak has been a reoccurring problem. I had it welded shut and together to the downpipe but now the welds have cracked and low and behold, the leak is back. At least it isn't rattling like before. I picked up some Permatex Muffler & Tailpipe Sealer to seal it. It's rated to 2000 degrees F instead of that other silicon sealer which burned. Do you think this should hold or will another leak form again in the future? I've noticed a power loss throughout the entire power band and throttle response isn't crisp anymore. My gas mileage dropped from 32 to 28. I'm thinking that since the leak is where the header joins the downpipe right before the cat, the sensor is detecting more O2 and is making the fuel mixture rich to compensate for "unburned O2" ---> leak. I almost wish I had never gotten this header. It's caused so many headaches. First the leak, then rattling/buzzing, more leaks, buying parts to fix it which didn't work, more leaks, welding, more leaks... ugh.

you can't go back to the original header?

It's still welded to the downpipe. The weld is only cracked. It's holding the pieces together still. I just hope the sealant will solve the problem.

i have no idea but if you have those infrared temperature sensors, find out with those. hehehe

A flange is just more work for a simple problem. I'll just seal the leak with the muffler sealer and use the stock clamp with more sealer. It was suggested that I weld in a flex tube. It would reduce the stress on the joint. It seemed like a good idea, but I'm not keen on spending money for an expensive solution. I'd rather fix it as cost effective as possible.

Flex pipe.

/thread

why did your welds crack? what's the problem with this header? can't you cut and make it fit perfectly to your exhaust pipe?

ohh yeah, flex tube!

The question is whether or not you want to permanently weld the flex pipe from the header to the downpipe or if you want to flange it as well so that it's removable.

i believe that the first sensor pre-cat is actually the one that controls your fuel. the second one after the cat is only there to determine if the cat is working or not. i don't think having the leak where the header meets the exhaust pipe would be able to affect the first o2 sensor to through off your mileage.

so if i just put a flex pipe then im good? im asking bec. im in the process of buying one from someone.

I'd go to a reputable exhaust shop and get them to take a look at it. Get a few opinions from some shops that would be willing to do it, and weigh your options.

Placebo lost horsepower?

Ok, when I went under the car to seal the weld, the weld looked completely intact. It was completely solid. No cracks... I'm perplexed. I slathered the sealer all around just in case and let it set and cure. Then I started it up and let it idle for 10 minutes like the directions said. I took the car for light driving, keeping the RPM's below 2.5k and the ticking noise is still there! I checked the entire header from top to bottom using a bright flashlight to see if I could spot any soot and carbon build up in a certain area. Nothing. Maybe I'm just imagining that I have a leak. I always thought it was just engine noise due to the valves and the aftermarket header being so thin compared to the stock manifold until someone riding in my car asked me what that ticking noise was. Ever since then, I've been super paranoid and perhaps imagined that I was losing power. Placebo lost power. LOL I've read that a leak would sound like a ticking or hissing. That's what got me worried.

Does anyone with the Forza header also hear a ticking noise upon acceleration that goes away once speed is reached? Or if you add gas when cruising at a constant speed? Is this noise common if you have an aftermarket header? Jon, you have the same intake and header. Maybe you have the same sound.

yeah, i've got the ticking sound. i really dunno if it's a leak.

If you have it too then I think it's just the rasp of the header. The stock manifold was so thick it acted as a resonator. The Forza is thin so you can here the valves much easier. Whew!

why not weld the flexpipe? why would you need it to be removeable?

Well, the flex pipe is not an issue now. What I'm concerned about is a possible exhaust leak. What does an exhaust leak sound like?

i had an aftermarket header on my ae92 4af engine. after the install it had leaks. so the muffler shop guys said that they will have to weld and patch up a few areas. i heard the exhaust leak the first time. it sounded like a helecopter! after the pipes were welded better, there was a little bit of ticking. that's my experience with an exhaust leak. ohh the header i had for my 1989 corolla was a pacesetter. according to the muffler shop i took my header to, they say they produce power, but the manufacturing sucks. their experience with the header welds were not good. so a little but of fabrication to the weld joints needed some attention to stop leaks.

Ok, good because it is a leak. A huge one from the sound of it. My car sounds like a lawnmower. My header is welded to the downpipe so I can't remove it. Will the exhaust shop be able to fix it with out removing it? I have lost so much power that it's ridiculous. There is no way I could be imagining it.

Jon, how is your Forza header working out? I've developed a leak so yours will be prone for leaks as well. Do you know of a muffler shop that's any good?

So I drove it around on a secluded road with the radio off and the windows down. I heard a pulsating hiss that got louder with the gas and that disappeared the second I let go of the throttle. It's definitely a leak. The power loss I thought I imagined is not possible on this level. I have lost a LOT of power. I have to floor it to get it to go uphill while the car sounds like a lawnmower. I checked the weld that connected the header to the pipe so that isn't leaking. Where is the most common place that aftermarket headers would form a leak?

That's really interesting.
Just a wild guess, check your O2 sensor. Maybe the gas leak from there.

I hope the header that I have don't have this problem. I bought the long runner one and it's still sitting in my room.

Yeah, I'm going to check the O2 plug and gaskets. I'll tighten everything again to specs. Hopefully that will solve the problem. I localized the sound. It's coming from the motor. It's either a leaky exhaust gasket or cracked at the flanges. I hand checked the welds this morning when the engine was cold. There was no soot or carbon build. It's most likely a leaky gasket.

Well, the header gasket is new. The Forza header came with a new one so I know it's not a bad gasket. I tightened down the header bolts. Some of them weren't torqued to the specified 26 ft/lbs. I actually torqued them just a bit more to 30 ft/lbs. 4 ft/lbs shouldn't cause any problems. Better safe than sorry. I haven't been able to drive it yet. When I head home tonight, I'll find out. I hope that the leak was due to the bolts not being tightened enough. *cross fingers*

That really sux.
I think for those who have aftermarket header really need to use a flex pipe.

I finally found the leak. It's huge. I'm about to cry it's so big... I can't see it from the top vantage point, but I can feel it. It's right on the collector tube where the runners meet in the middle. Another sad thing... my Forza emblem on the header fell off! Luckily it got wedged in the engine compartment and I picked it out. Here's a diagram of where the crack is. It's so big that it goes halfway around the collector tube.

Luckily, there's a gap underneath where the rain guards don't cover so the crack is exposed to the ground. That will give an exhaust shop easy access to weld it shut. Now I just have to find time to bring the car to a shop. This sucks.

good old google searches!