Rock

So, I take her over to the local spray wash to give her a quick Sunday morning cleaning and on the way home I decide to open her up a little bit. I slow down and then punch it and Bang!!! it sounds like I have an open exhaust. I also hear a loud rattle and feel a huge loss of power.

When I get home to check it out, I can not detect the cause but it sounds like it is emanating from the under the engine. Any thoughts? This is the first problem I have ever had with this car.

WayneE

Do your headers have AIR tubes? I've blown an AIR tube off a set of headers and had something similar happen. You could have broken a weld on an O2 bung and blown that out of the exhaust, too.

I hope this is not the case, but I know several people that have blown plugs out of their heads. It took the threads and everything with them. We had to pull the heads, helicoil the plug holes and reinstall.

Keep us posted!

Rock

Wayne,

They are Kleemann headers, I'm not sure about the Air tubes but I don't think they have O2 bungs.

rflow306

Rock, It's probably coming from the collector, check your collector bolts (where headers attach to the exhaust). Make sure they have spring washers or jam nuts or the problem might return.

Beowulf

^^^
If that turns out to be the prob, I've had excellent luck with Stage 8 locking bolts.

Insigno E55

Like the previous poster said, bigger chance for the downpipe area. For the manifold to come loose will take alot of giving unless it wasn't torqued down tight enough during header swap. If that's the case then the exhaust gasket is probably blown through. I would check the collector area where the downpipe meets since that's easiest to check.

Wayne

absent

My G is currently in service ,waiting for new headers from Kleemann.
It's more then a year,almost 20k miles but they were nice enough to give me a free replacement(I pay for labor)
The original ones cracked and the leaking fumes gave me a real headache for a while.

ProjectC55

If you have the cats on the car ,I know when the insides are blown out they can make a rattling sound as well.

Rock

Guys, thanks for the suggestions. I tried to lift the car for a closer look at the connections but I could not get good access. The thought of a 4200lbs sedan accidentally sitting on my chest made me come to the conclusion that it will wait until Monday.

Absent: When your headers cracked were you also getting rattling, loss of power and loss of hearing?

Grumpy666

I find the loss of power a little confusing. A simple exhaust leak shouldn't cause this - unless the rattling (or harmonics from it) is triggering the knock detector, which pulls timing.

Insigno E55

I think his leak is much bigger than just a simple exhaust leak, he mentioned he got 'loss of hearing'.

Wayne

absent

Rattling,loss of hearing are normal occurences of daily driving in a G55.
Loss of power would have nothing to do with a faulty header though...

FlyByNight

Yikes... hopefully this isn't more complicated than a major leak / hole / detachment of some kind. Whenever I've heard "bangs" followed by low power, its been major.

Any smoke in the exhaust, any error messages... how much power loss? I mean, can you tell if the supercharger is still functioning / engaging?

double yikes...

Rock

Loren,

Sorry, I wish English was my first language. What I meant by "bang" was, "all off a sudden." There was no actual bang (loud pop).

Today, as soon as I floored-it there was the obnoxious sound of an unmuffled exhaust and no kick-in-the-butt SC engagement although I immediately eased off the throttle and nursed the car the rest of the way home. No fault lights came on so I'm not sure what happened. A few days ago, when I accelerated quickly, the car sounded different but I didn't think much of it.

Damn, I hope it is nothing major. I already shot Cory an e-mail..............I wonder if he's getting tired of us yet.

jangy

wish you the best.

Vetluver

Can you tell whether the sound is continuous or does it sound like....rrrmmp.......rrrmmp.......etc. In other words does it sound like one, 4 or all the cylinders making the racket?

Rock

Vetluver,

You only notice the racket when you push the fast pedal. It sounds normal when it is idling.

Kens-E55

Rock: Any news yet?? As a fellow K2 going to K3-I,m quite interested to make sure it's something minor??
Any results on the noise problem??

tama_mog

First thing I'd do is look under the car for fluid leaks. If nothing then jack up the car and just take a look from under, see if there's anything obvious. If it was an exhaust leak it'd just be louder than usual....but should not really lead to a dramatic loss in power in anyway....unless like grumpy says the knock sensors in these cars are that sensitive.

Rock

Hi Ken,

My car will actually go to the dealer on Wednesday so I will update you as soon as I get any word.

I also spoke to Cory today and he had a few thoughts on what may have happened. These are his guesses:

#1: The weld between the kleemann down pipes and the stock exhaust has failed
#2: The collector gasket has failed and/or the bolts for the collector have failed
#3: The stock exhaust system down stream of the KLEEMANN parts has some kind of problem
#4: The KLEEMANN header has developed a crack, although he highly doubts it, as he's never seen a W211 header fail before.

Cory also said: "a major exhaust leak like that will have a fairly significant effect on how much power the car makes. I doubt this is anything major, such as a mechanical issue with the engine. I believe it's limited to the exhaust system."

rflow306

Rock stop being a wuss. Get yourself a good jack and some jack-stands and get to work.

Rock

I think I'd rather change my screen name to Marshmallow.

WayneE

Rock, I took your description of a BANG as you hearing a loud noise, as if something catastrophic had failed. Your further descriptions make it sound less ominous.

Run by an exhaust shop, slip them $25 and ask them to throw it on the lift so you can examine the exhaust.

newton22

Oh come on, getting under the car ain't that scary.

rflow306

Okay forget my idea, Wayne's plan is better.