Sooty Tail Pipe

[MikeTEC]

Hope someone can help. Recently bought a clean 96 5.0 limited, original owner, with 91K on it. I gave it a good check, the tail pipe was clean, drove and ran well. Took it to my Ford dealer and got an evaluation from a Master technician I have used for years. Only thing wrong was a slightly leaky A/C compressor. After I bought it, had him to install new hoses, belt, thermostat, coolant, fuel filter,air filter, and change the tranny fluid. (Mobil 1 Synthetic) Now I am getting a sooty residue in the tailpipe. Gas milage is unchanged, about 20.5 on the highway and does not appear to use any oil. Any ideas why the soot and possible solution? Thanks Mike

 

[mrboyle]

"Soot" in the tailpipe is a sign of an over rich running condition. My first step would be to replace the O2 sensors.

 

[MikeTEC]

Mike: Could the change to a new thermostat have caused the problem? We used all motorcraft OEM parts, ect...The temp guage is about where it was before, perhaps a little cooler, but not much. Also, I noticed the sooty pipe after my wife and daughter returned from a 600 mile trip. MikeTEC

 

[mrboyle]

The only way I could see the problem being the t-stat would be if it was stuck open and not allowing the engine to warm up fast enough. I have seen several t-stats that were junk right out of the box, so even though it is new, doesn't always mean its good.

 

[MikeTEC]

Mike: Which sensor(s) would you start with or do they all have to be replaced. Is there one particular O2 sensor on 96-97 5.0 Explorers that tend to go out first? Thanks Mike

 

[mrboyle]

With the amount of miles your X has on it, I recomend replacing all the sensors. According to Bosch the life expectancy of most O2 sensors is between 80K -90K miles. I know the damn things aren't cheap, so if it isn't in the budget to replace all at once, start with the two in the head pipes (before the cat). Then as soon as it is possible replace the other(s).

 

[MikeTEC]

Thanks, Mike. Probably will need to save my pennies and do them all. MikeTEC

 

[MikeTEC]

Mike: Hope you dont mind another question. Wouldn't the check engine light come on if an oxygen senor was bac? Thanks MikeTEC

 

[mrboyle]

Yes and No! If the sensor fails or the readings are way beyond the set parameters it will set the CEL. But, as long as the sensors are still reading within their given parameters (even though they are might be reading at the very edge) they won't set the CEL.

 

[MikeTEC]

Thanks, Mike. Hope my wife and I can make it to Colorado with my travel trailer one day, in the summer months, to escape the 112 degree summer heat here in Texas. My 93 Eddie Bauer has been and still is, a faithful tow vehicle and never has let me down. Hope the 96 5.0 liter I just bought is just as dependable, but with more power, to handle the Colorado mountains. Mike

 

[mrboyle]

I know what you mean about escaping the heat. I gerw up in Arizona (didn't mind the heat as much there) and spent a year in Oklahoma (couldn't stand 100+ weather w/50+ humidity).

 

[MikeTEC]

Well folks my sooty tailpipe cleared up and now there is no residue at all in the tailpipe. The only thing I can figure is the 600 mile trip my wife took the X on burned off some carbon in the engine or I got some bad gas. Still no oil useage and 20-21 MPG on the highway with A/C on.