Dumb Little Observation: Condensation in Exhaust

[HawkRod]

So I know that running your car for short periods of time builds condensation in the exhaust and can speed rusting it out.

When I started the tear down of my car, I ran it for a short period two days in a row. When I pulled the mufflers off water POURED out of them. While all of the water poured on the floor for the first muffler, I tried to capture it when I pulled the second muffler off. What you see in the picture below is the water that came out of one muffler, minus a little bit. AND there was still some water trapped in the mufflers that I couldn't get out.

Wow, that's way more that I would have ever expected!

 

[Photon440]

Long trips aren't part of your driving routine are they? One shop where I've had new exhaust put on a couple of cars would punch a 1/16th hole at the bottom end of the mufflers to let it drain out.

 

[tallhair]

I've seen small holes in mufflers too and sounds like a good idea unless someone knows why it's not

 

[Cranky]

Yup, short runs produce a lot of condensation. A cold engine going to warm produces a lot in itself and then you have the exhaust system doing the same thing. This is also why short tripping a lot your car makes the oil look dirty so fast and is another reason you need to change it more frequently.

 

[A383Wing]

poke 2 small holes in the ends of each muffler to allow the water to drain when it cools....we have had many threads on just this issue....

holes go in end of muffler just above the bottom seam...not underneath the muffler itself

 

[tallhair]

Yes that's what I'm remembering A383

 

[A383Wing]

we just finished a thread on this where owner of car was getting gallons of water out the pipes....long story short, muffler shop had installed mufflers upside down with the holes at the top...he drilled 4 holes at the bottoms of mufflers, and got drenched with water when he pulled the drill out....

you can use a sharp punch as well.....1/8" or a little bigger will be fine....just don't goo too big, or you will get noise that you don't want

 

[Cranky]

poke 2 small holes in the ends of each muffler to allow the water to drain when it cools....we have had many threads on just this issue....

holes go in end of muffler just above the bottom seam...not underneath the muffler itself

I recall seeing new mufflers come with the holes....

 

[A383Wing]

yes...and the reason why is exactly what this thread is about...if water pools and stays inside...mufflers will rot out in no time

this is for stock style mufflers, not glass packs or straight through styles.

Cheap offshore mufflers probably won't have the holes.....and a lot of mufflers only have one hole in the rear, but I always put a hole in the front as well

 

[Photon440]

Not my post...someone put this on an altogether different forum a year ago. But it's interesting:

Funny you should mention it, we have had 2 Audi's and 1 Mercedes in our shop this winter with no start conditions. All 3 would not start when the vehicle sat outside in very cold weather (10 to 20 degrees). After sitting in the shop for a few hours they would start up. The first we had in was the MB, it took us well over a week to get it diagnosed. The exhaust system was full of water and would freeze solid when cold enough, it would block the exhaust system 100% shut, resulting in a no start. First car I have seen in 17 years of business that would not start as a result of water in the exhaust. Well 3 days later we got another cold snap and in came a Q7 audi, had only 43k on it and would not start. We checked all the basics, spark, fuel pressure and ECU codes, all checked out fine. With the MB still lingering in our minds we checked the exhaust and this one was froze up solid also. Later that week we got in another Q7 with the same problem. After these vehicles had the exhaust systems thawed out, we drill a 1/8" hole in the lowest point of the exhaust. All 3 cars had well over 4 gallons of water that was drained from the exhaust system.

Cars built nowdays have exhaust systems that contour the undercarriage much better than the old days, this results in more places for water to accumulate. This coupled with the ethanol in todays fuel can add up to problems.

I remember BMW's having issues with water accumulation in the exhaust system causing the o2 sensors to short out. We fought with many of them, BMW finally came up with a fix for it, drill a 1/8" hole 2" after the sensor to drain the water.

 

[Cranky]

Not my post...someone put this on an altogether different forum a year ago. But it's interesting:

Funny you should mention it, we have had 2 Audi's and 1 Mercedes in our shop this winter with no start conditions. All 3 would not start when the vehicle sat outside in very cold weather (10 to 20 degrees). After sitting in the shop for a few hours they would start up. The first we had in was the MB, it took us well over a week to get it diagnosed. The exhaust system was full of water and would freeze solid when cold enough, it would block the exhaust system 100% shut, resulting in a no start. First car I have seen in 17 years of business that would not start as a result of water in the exhaust. Well 3 days later we got another cold snap and in came a Q7 audi, had only 43k on it and would not start. We checked all the basics, spark, fuel pressure and ECU codes, all checked out fine. With the MB still lingering in our minds we checked the exhaust and this one was froze up solid also. Later that week we got in another Q7 with the same problem. After these vehicles had the exhaust systems thawed out, we drill a 1/8" hole in the lowest point of the exhaust. All 3 cars had well over 4 gallons of water that was drained from the exhaust system.

Cars built nowdays have exhaust systems that contour the undercarriage much better than the old days, this results in more places for water to accumulate. This coupled with the ethanol in todays fuel can add up to problems.

I remember BMW's having issues with water accumulation in the exhaust system causing the o2 sensors to short out. We fought with many of them, BMW finally came up with a fix for it, drill a 1/8" hole 2" after the sensor to drain the water.

Wouldn't want to try to explain that one to a customer lol