If that title comes off like the tag line of a 1950's horror flick, good. That's exactly how I feel about exhaust leaks -- the automotive equivalent of horrible monsters! This is ironic because in the grand scheme of automotive issues they aren't a very big deal. They don't impact a car's operation in any way.
And no, you can't die from the type of exhaust leak I'm talking about, which is a small break in the gasket between the engine block and the exhaust header. It's actually quite unlikely to die from any exhaust leaks, unless they somehow cause the fumes to seep into the cabin and you sit stationary in an enclosed space for a long period of time. Most exhaust fumes are simply scattered by the movement of a car going down the road at any pace greater than a brisk walk.
Anyway, I think I hate exhaust leaks because they don't necessarily indicate a rolling pile of junk, but they can make even the most pristine automobile sound like one. If you've watched the movie Christine and remember the scene when Arnie first drives the evil car home the image is supposed to be that of a total rolling wreck. Among the trademark features (beyond the rust, dents and rotting interior) is a prominent exhaust leak that really makes the old Plymouth come off as a pile of...bad stuff.
Well, I don't like my cars to come off as a pile of anything, but my Dodge Challenger R/T has stubbornly emitted an exhaust leak since I purchased four years ago -- despite several repair attempts.
I first noticed the leak while driving the car through Nebraska after buying it. When I got to Denver I had my local Mopar connection go to work on it by tightening down the exhaust header bolts. This usually doesn't work because once an exhaust leak develops it almost always blows out the part of the gasket where the leak developed. Tightening the bolts doesn't replaced that missing gasket material, it just crunches down on the remaining material. But it was a fast and easy repair attempt so they gave it a go.
It didn't work, but by cranking down so hard on the bolts it caused one to snap as I drove the car home from their house, after the headers heated up and expanded. Now I had a busted, 36-year-old, completely rusted out bolt jammed in the header, along with a much louder exhaust leak. After a delicate (and expensive) bolt removal the gasket was replaced and the exhaust leak was gone...for awhile.
But it came back within a few weeks. I drove it that way for a few months but finally took it to a shop in Southern California where the gasket was again replaced. This time the shop had the header checked and then shaved down slightly to deal with some warping that had developed. Obviously that was going to finally solve this problem, right?
Wrong. The leak came back a few weeks later, again. I took it back to the shop. They replaced the gasket again. Once again, the engine properly purred and sounded like a finely tuned machine -- for about two weeks, then the dreaded "popping" came back. This time I tried cranking down the header bolts almost immediately, hoping I'd get at the leak before the force of the escaping (and annoying) air punched a hole in the gasket again. It worked! The exhaust leak was gone. For awhile.
Two days ago I tried cranking down the bolts one last time, and I'm hoping none of them snap the next time the engine gets up to full operating temperature. But even running the engine a short time after tightening the bolts confirmed the leak was still there (though it seemed a couple notches quiter; almost imperceptible really).
But like the zombies from a horror flick, I'm sure it will return again. BTW, these bolts are a nightmare to get at. You can see one just above the spark plug and part of another one near the flecks of Hemi orange engine paint. For all the engineering prowess I like to attribute to Chrysler during the muscle car era, the design/location of these header bolts simply sucks. Don't even get me started on the one futhest back...right next to the steering shaft and essentially impossible to tighten.
Maybe my car really is cursed like that famous '58 Plymouth.
By greenpony
on April 8, 2010
10:48 AM
I like write-ups like this, real problems with real cars. Here's hoping you finally get to the bottom of it.
As a side question, wouldn't an exhaust leak such as this have some impact on a modern car? That is, wouldn't it affect the O2 sensor reading?
By johnnyturbo
on April 8, 2010
11:30 AM
I'd put on a set of headers and exile the stock manifolds to a plastic bag.
By iskch
on April 8, 2010
11:42 AM
Sounds familiar. I fought the same devils with an International Loadstar 2 ton truck several years ago. Got tired and dab some high temp silicon on a new exhaust gasket. Yes, I know is a no no but worked! Also try to even out the surface.
By editor_karl
on April 8, 2010
02:18 PM
greenpony -- You're right, an exhaust leak would mess with an O2 sensor on a modern car. Hadn't thought of that.
johnny -- I'm trying to keep the car as "unmolested" as possible, but the headers are going to become a real possibility if I can't fix this annoying leak.
iskch -- Hadn't considered high temp silicon. "No-no" my foot. If I can get that to work I'm all over it! Thanks!
By deagle13
on April 9, 2010
09:05 AM
C'mon Karl - I can't believe you haven't tried the fix-it-all combo of JB Weld and duct tape...
On a more serious note, do you think you might be running a little lean or with a bit too much spark advance which is leading to higher exhaust temps that are burning through your exhaust gaskets? Or, if the leak is recurring in the exact same spot, have you had the exhaust ports on the head examined for surface imperfections/warping (since you already had the manifold smoothed)?
By cheslin
on April 9, 2010
10:20 AM
My first thought was that your head has a low spot that creates the weak point on the gasket. I had an old 351W that I did the hi-temp silicone on and it worked like a charm until I blew the tranny in that car.