General Question

Fred931's avatar

What is this exhaust smell in my car?

Asked by Fred931 (9371 points ) October 7th, 2012

After some unparticular amount of driving at pretty much any speed, once I come to a stop, this nice exhaust fume wafts into the cabin. It is very pungent and irritating. I feel for fellow motorists around me. But I’m not sure if it is a rotten-eggs smell or just a plain exhaust smell. It is definitely the byproduct of combustion and not just raw gasoline.

If I won a million bucks for guessing the right answer right now, I’d say it’s the exhaust manifold crossover. On each of the 5000 or so TGPs that have been made, the crossover is highly prone to leaking. Can you give me an idea of what to check for on the crossover to indicate that it is leaking?

If you’re someone who responded on my question about exhaust work, know that I haven’t done anything yet and will probably invest my money on things that actually need repairing, such as this.

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5 Answers

Tropical_Willie's avatar

Rotten egg smell in exhaust is from catalytic converter. Caused by sulfur additives in your gas, try changing brands of fuel and go up a grade at a new gas station for two or three tankfuls. The smell comes from sulfur being converted to hydrogen-sulfide in the converter. A complete tune-up with spark plugs, air filter and timing check will also help.

I had trouble with Shell brand of fuel on a Ford and switched brands of fuel, the smell went away in less than thirty gallons of gas.

CWOTUS's avatar

As an important side note – and maybe you don’t need to know this, but others reading the thread may need to be informed – any time you’re smelling exhaust fumes in the cabin of the car it means that you’re also inhaling carbon monoxide. Carbon monoxide is lethal. It won’t take a very long or concentrated exposure to it to overcome you, making you first disoriented and headachy, then sleepy, then unconscious and finally dead.

Definitely get this fixed, one way or another, before driving the vehicle much farther.

gailcalled's avatar

After some unparticular amount of driving at pretty much any speed, once I come to a stop..

Do you mean that the smell occurs no matter whether you have been driving for a long time or a short time and is not dependent on your speed?

If you back down the driveway, can you smell it, or do you have to drive more?

woodcutter's avatar

If you smell it inside then I think it will come through the firewall from the engine compartment An exhaust leak under the car should be carried away unless you have a hole in the floor pan or you smell it when the windows are down. Are you smelling stuff from other cars because the air handling system in the car will draw that inside. That rotten egg smell usually happens when the engine is being pushed hard with rapid acceleration but that too could be coming from someone passing you.

Fred931's avatar

It only took me a couple more drives to really pin down that it’s just an exhaust smell and not sulfuric. I will be replacing the catalytic converter, however, when I work on the catback system in the future.

I think if it is the crossover or something near the manifold that is leaking, then the bad air can’t accumulate in the cabin because there’s enough fresh air from driving that it’s undetectable in the cabin then. When I decelerate to a stop, there’s enough lack of fresh air moving through that the exhaust still going around the turbocharger has a chance to accumulate and waft through the AC or just panel gaps. It would make sense the crossover leaks as the pressure in that pipe building up and escaping through cracks would explain this.

I’m taking it to the shop to check that x-over and the rest of the manifold for leaks. Thanks guys.

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