Georgia Fiero Club Forum

All Things Fiero => Tech Tips, Tech Questions => Topic started by: pgackerman on October 25, 2018, 10:26:09 pm

Title: Exhaust Sludge
Post by: pgackerman on October 25, 2018, 10:26:09 pm

Two days ago I went for a 160 mile road trip with my '88.
Yesterday, when I restarted the car after having already driven it 15-20 minutes, sludge(?) spit out the exhaust and landed on my driveway.  The good news is the dark oily sludge came out forcefully.  The bad news is it can still be seen on my driveway.

The weather was beautiful so no water should have gotten inside.  Car is garaged overnight.  Oil is fine.

What caused the sludge to be spat out?
Is this a symptom of a problem?

Title: Re: Exhaust Sludge
Post by: GTRS Fiero on October 25, 2018, 10:36:44 pm

Describe the sludge.  Pic?

How did the car drive, 2 days ago?

Title: Re: Exhaust Sludge
Post by: pgackerman on October 26, 2018, 05:53:54 pm

Car behaved great two days ago.  Between 50-60 miles into the trip it felt even better.

Been raining all day.  No pics.

Title: Re: Exhaust Sludge
Post by: GTRS Fiero on October 26, 2018, 06:01:13 pm

Yeah, raining here, too.  Very annoying.

Title: Re: Exhaust Sludge
Post by: Fierofool on October 26, 2018, 06:07:56 pm

With the cooler temperatures and higher humidity, the system can experience condensation inside the exhaust.  When the engine is started, it can sometimes spit out a black soot mixed with water.  My cars often emit steam at first startup, even on a summer morning. 

I remember the Lil Duke Coupe would often spit out a stream of water from the tiny weep holes in the lower ends of the muffler.  I never could determine how water might get inside the muffler so it had to be condensation. 

Black soot might be an indication that a tuneup is needed, coolant temperature sensor or O-2 sensor needs replaced or there may be other factors causing the car to run rich.