Condensation from catalytic converter?

[tominwi]

Our Expy sits for many long days in our "somewhat attached" garage which here Up North is normally 40-50F temps this time of year. Yesterday I started it and let it run for a minute before backing-out of garage, and leaving the vehicle running on the concrete apron I noticed it had drip-drip-dripped what seemed like drops of water. Peering under the vehicle there had accumulated like a half-teaspoon of water on a couple of the low edges of the catalytic converter.

Do yins agree this was just condensation? Seems a no-brainer but I'm just a little surprised that the cat would heat-up that fast to release the moisture on it after just a minute or two?

 

[bb37]

It's probably condensation. One of the byproducts of combustion is water vapor. When the vapor hits a cool surface, it condenses into liquid water.

Are you sure you were looking at the catalytic converter and not a muffler? I believe that the exhaust on the Expeditions comes out of the turbos then goes through converters, one for each bank, that are close to the engine. I'm not sure you can see the converters without getting under the vehicle and looking up at them. The pipes then converge at a large muffler then run to a resonator then the exhaust outlet(s).

The converters will heat up very quickly and will keep the water in the combustion gases vaporized. But, when those gases hit a cold muffler or resonator, the water will condense.

 

[JamaicaJoe]

The ECU goes from open loop to closed loop within 4 minutes so I would suspect that is enough time to get the catalyst up to temperature.

 

[Left Coast Geek]

the converters should be tucked right up along side the engine just below the turbos and before the first mufflers sometimes called resonators.

most common source of water drips is the air conditioner evaporator, there's one under the dashboard, plus another in the back left corner for the back seats

 

[bb37]

plus another in the back left corner for the back seats

Left corner? I thought the rear HVAC was on the right (passenger) side.

 

[tominwi]

Couldn't have been from the AC; it was not running at all. But I guess I ASSumed the drips were from the catalytic converter--it was a largish (16" x 20"? dunno, guessing now here at my desk) that was just ahead of the rear wheels i.e. the first thing back from the tailpipes. Resonator? I am not a car guy.

 

[5280tunage]

maybe a leaking/blown shock? those have left small puddles for folks before. in that area, the only way it could be condensation from the exhaust would be if you have a leak someplace. Is the substance oily or was it just water and evaporated quickly?

 

[bb37]

it was a largish (16" x 20"? dunno, guessing now here at my desk) that was just ahead of the rear wheels

Sounds like the muffler. Many mufflers have small weep holes in them to let the condensation drain out.

 

[Left Coast Geek]

engine is off the lower left corner of this diagram...
cats are 1 & 2, right off the exhaust manifolds
main muffler is the big can on the front of part 8
rear muffler is part 16, right at the back of hte car, with the tailpipe hanging off it.