Engine Exhaust leak robbing power.

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.

If welds wont hold I wouldn't expect silicone sealer to. Did you use OEM spring bolts between the header and midpipe? There need to be some flex in the exhaust system because the engine moves around a little when it pulls, switching gears, etc. If not my recommended fix would be to weld a flex pipe between the header and cat.

The header doesn't have a flex pipe like the stock one did. I don't think the cost of welding a flex would be worth it. I just want to have the pieces pro welded together preferably MIG or TIG welded instead of that solder welding they did at the exhaust shop. It did hold for several months with no leaks though.

yea bad welding could be another factor.. but I would highly recommend getting a flex pipe put in if you don't want the problem to resurface.. they're not too expensive if you know where to buy it. Here's a local place I've been to
http://www.atpturbo.com/Merchant2/merchant.mvc?Screen=CTGY&Store_Code=tp&Category_Code=FLX

Alright. Thanks a bunch! btw, have you heard of people using Teflon tape to seal exhaust leaks? I did some research and others have been doing that. Teflon has a melting point of 327 degrees C so it makes some sense. How hot does the header/piping get typically?

i would assume you have a header that uses a ball and socket flange, rather than a flexpipe....

i have the exact same problem.... which is that the exhaust system is meant to have flex in it (because the motor mounts have flex in them)... but the ball and socket doesn't allow for flex....

you can start by trying to install exhaust spring bolts... but at least in my case it didn't help....... if you go that route you could also attempt for a soilid front motor mount...

otherwise you should think about having a flexpipe attached....

as for me, i just drive around with it leaking.... doesn't sound bad out of the 4ag

I'm going to seal the leak with the muffler sealer and then use the stock clamp with more sealer. That should do it.

flex pipes ftw.... atleast I know a good welder... good luckon the sealer

Thanks. If it doesn't work, I'll shell out for a flex pipe and welding.

if it doesn't work (which it probably wont) then you'll have to cut out the entire area you're patching.... most welders hate having to work around the stuff

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 and no cracks. 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?

damn is a flex pipe that expensive? how much do the ycost

Around 30 bucks.

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? Maybe at the collector tube where all the runners join? Or maybe at the block where the runners start?

my problem comes from the gasket or donuts as the people here call them, when the flexing of the engine happened,

they cutted all of them and installed flex pipes

Only true way in finding the leak is to tank test the mainfold. That's what we do after we make a header - cap it at the exhaust flange, attach a homemade cap on the end of the collector - stick it in a tank of water and pump air into the header. If the are any bubbles - you know you have a leak. If that checks out - then you need to work down the line until you come across the real culprit.

Found the leak!

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.

shouldnt they just be able to go under and weld it than? it doesnt look SO bad but it must suck.

Got it fixed this morning. Apparently, I also had a leak further down after the cat. They caught it and fixed it while they were at it. Really great shop. I'd recommend any one to them. http://www.americanmufflerandbrake.com/ The noise is gone, power is back, and vibration is down. My car as I knew it is back and better since I did a Royal Purple oil change since then.

o shit i think im having the same problem....i hear sumthing when i rev..im not sure yet.

Legit01Rolla added 114 Minutes and 49 Seconds later...

how much did u pay to get everyhing fixed?

20 bucks for a simple weld to seal the crack. I eventually had to get a flex pip installed and had my exhaust redone. That was 267.

what kind of sound is it?
i hear a sound too, just like when i had my ported oem exhaust manifold and it sounds like air rushing through the exhaust manifold/header. i guess it was audible with the exhaust manifold since the beginning of the runners from the inside was dremeled so that it was sharper and i guess air was cutting through it

and yeah, i still have my CEL which im going to leave on for a while till I get some money.

If you have a leak, it will sound like a loud ticking noise that has shorter intervals between clicks as you accelerate.

oh ok, def. dont hear clicking sounds

i think thats what im hearing..but not that loud thou

Mine wasn't that loud either until the crack got larger.