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Exhaust discharge...

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Nunyas

Nunyas

Yoda
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I remember reading a thread not too long ago where someone was commenting on a liquidy black substance being discharged from the tail pipe of their car right after starting. But I can't for the life of me figure out what thread it was. So, I thought I'd ask again and see what the common concensus is. In short, the exhaust shoots out a liquid substance that's black, but it comes out at a velocity that you cannot see the stuff being shot out. However, anything behind the car will get this stuff sprayed onto it. For example, anyone that parks behind me on the street will have a nice "black eye" on the lower parts of their front bumper in the morning. It is not a continuous discharge; it clears up/stops shooting this stuff out when the car has fully warmed. I think it may be from moisture in the air condensing inside the exhaust when it cools and mixing with whatever black stuff is in the exhaust system, and then gets shot out when the car is started again.

The thread I was reading seemed to have a few people that experienced the same problem, and some people that had more than one MGB had the problem with one car but not the other. I'm wondering if there might be a way to ensure it does not happen. Maybe exhaust routing, or something. My car is a '76 with after market catalytic converter, and the exhaust currently goes up and over the axel. I need to change it because the axel touches it on big bumps now (because I lowered the rear 1").

Anyone here have this problem in the past and figure out a way to fix it? Also, I'm wondering if there's any kind of commonality between cars that are experiencing this discharge....

any and all feed back on this topic is appreciated.
 
Likely it's water condensation in the exhaust system. Sounds as if you're running RICH, not lean from that post, man. What color is the inside of the ehhaust pipe at the exit? Sooty black would indicate an overall rich mixture... as long as it isn't "oily" as well (that would be a "bad thing").

It wants to be cocoa brown to be right. Just like the plug colour.
 
I have had the same thing happen with my 1500. I kinda figured it was just from being choked and running rich. I think your water condensation idea is on the right track tho.

mark
 
The tail pipe on my car is sooty... but it was sooty long before I got a hold of her, and she was billowing clouds of black smoke when I brought her home. She's definitely not doing that anymore. I've been contemplating on how I want to go about the exhaust system. Been bouncing back and forth between buying a "ready to install" kit or piecing together a kit from generic pipe bits...
 
Ya gotta keep th' CAT, but from there back, I'd say go with ANSA. Only 'cause Stebro's can't be had anymore /ubbthreads/images/graemlins/wink.gif
 
ya know... I noticed AutoZone sells "Cherry Bomb" mufflers now....
 
[ QUOTE ]
Likely it's water condensation in the exhaust system.

[/ QUOTE ]
It IS mostly water, as is the white "smoke" from the tail pipe. For every gallon of gasoline burned there is nearly a gallon of water produced as a by product. If the exhaust system is hot enough to completely turn the water to steam, you won't see much at the tail pipe. When the exhaust system is cold, nearly all of this water condenses on the cold metal & blows out the back as water. Since it carries carbon from inside the exhaust with it, a black mess blows out. If you live in a cold climate you will see a lot of steam as it condenses when it hits the cold air, even with the system hot.
D
 
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the exhaust currently goes up and over the axel

[/ QUOTE ]

Don't think 've ever seen that on an MG....wonder if it could be acting kinda like the water trap under a sink - keeping condensation in the part of the tailpipe between it & the muffler that's under your seat?
 
that's what I'm wondering... the muffler is indeed under my seat maybe slightly aft... the middle exhaust bracket is attached right behind the muffler and the cat under my feet...
 
I have the same thing with mine...but I have no cat and stainless steel routed under the axle. It is just water picking up the carbonin the pipes and should stop once the engine warms up. /ubbthreads/images/graemlins/blush.gif

And if anyone has to come that close to you when in traffic, they deserve the "black eye" /ubbthreads/images/graemlins/smirk.gif

Bruce
 
[ QUOTE ]
cat under my feet

[/ QUOTE ]

...what year car do you have? I've never seen a cat down there.
 
I have a '76. Instead of going for the over priced original style cat, I had a muffler shop install a "high flow" universal fit cat. The car was configured in the same manner when I bought it too. It uses the down pipe from the non-cat cars of the same generation with the cat connected to the end of it. I think I may need to replace the down pipe when I go about redoing the exhaust system. The down pipe no longer has the second bend to point it aft. It only has the first bend to point it down now.
 
is this carbon water mix that's expelled by a cold exhaust the inspiration behind the "Exhaust Deflector" that Moss is carrying now?
 
Probably so -- Sulfur dioxide is another combustion by-product. When mixed with water it becomes sulfuric acid. I have an old bumper on which the chrome is severly stained & pitted by acid emissions from a too short tailpipe.
D
 
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