Gurgling noise from exhaust at idle

[Oliseles]

OP, does it happen after you've been driving a while? Or only after the car's been idling for a few minutes or longer?

Betcha CAN$20.00 (which is, what, US$475.00 by now?) that it's exhaust water vapor collecting inside the muffler.

(glad you bumped the thread, because I've got a cool story about it!)

----
Where I used to live, just a couple blocks from the US Capitol, there's been a police cruiser posted on the street corner nearly every day. They'd sit with the engine idling, as cops always do.

One winter day, I'm walking by the idling cop car and I hear the exact same sound your car is making. Sounded like water gurgling in a pipe. I stopped and asked the cop, Do you hear the noise in your exhaust?

He says, "Yeah, it happens when it's cold. It's just the water sitting in the exhaust."

"Oh, I got it," I say, "Because you're just idling, the muffler doesn't get hot enough to make the water evaporate like it usually should?"

"Yup, that's it," he said.
----

To expand on this --

The action of burning hydrocarbon fuels like gasoline always makes water vapor. It's just how combustion works.

Normally, driving around pushes enough hot exhaust through the system to keep everything warm, all the way to the end of the tailpipes. Because the piping is warm, the water vapor stays in a vapor state and doesn't condense into liquid.

Now, when it's cold enough, and/or humid enough, and the engine isn't under very much load (load creates hotter exhaust) and isn't being revved (higher revs move more exhaust), the farthest reaches of the exhaust system -- here, it's the mufflers and tailpipe tips -- might be cold enough that the water vapor from the engine condenses into liquid water. This is just like how water condenses on the outside of cold drinks, except on a bigger scale.

HOW TO FIX IT:

Don't idle so much. Drive the car.

Awesome!!! Thankyou BARRACKSSI!
I must say your little story was very insightful. Thanks for the technical explanations too.

First thing first.
According to your whopping conversion rate its the other way around my friend.
475$ canadian dollars should give me around 20 american dollars to visit the wonderful UsofA and live the american dream with my canadian lemon civic.


Then let discuss it.
The right exaust NEVER EVER makes this sound when the engine is cold, i.e when I start the car. Never.
The exaust makes this sound when the car has warmed up and Ive been driving for a while.
And yes, once the car has warmed up and I need to idle for whatever reason, thats when its the loudest. Then again, I don't see how I could hear it driving 100km/hour on the highway...
And its also the loudest when its humid outside and even louder after a drive in the rain or after a rainy day parked outside not using it.
I know my car sat on the dealers lot for almost 10 months before they sold it to me. Tough luck. And since Ive had it, Ive barely used it. And when I use it its 90% of the time in the city, i.e lots of idle (although I drove my longest trip on the highway yesterday...in the pouring rain that is...).

so yes it could very well be water vapor/condensation collecting inside the muffler but i think it could also be condensation build up inside the gas tank...dont you think?

Either way, I still think its not suposed to do that...
This is my third car bought or leased new and they were all used and driven the same way.
3 VW and not one of them was farting like that.

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[Oliseles]

BTW -- go find a tuba player and ask what kind of sound their sousaphone makes in cold weather when it's full of "spit". They'll probably make the same noise.

Im a canadian man on a mission now. I need to find me a nice little tuba player.

 

[BarracksSi]

No, I don't think it's the gas tank at all.

Go drive it on the highway again (I believe you when you say that city driving is lots of idling and low-throttle driving), and try going around 100 km/h or so for at least 10-15 minutes. Then pull off somewhere, get out and listen right away, and I'm pretty sure you won't be hearing any gurgling.

There's a slim chance that one muffler side has started to corrode inside.. but I seriously doubt it. The possibility comes from the car spending the first part of its life being driven from one side of the dealer lot to the other, which warms up the engine enough to make water, but never warms up the exhaust pipes (and especially the muffler) enough to prevent vapor from condensing inside. Besides, it's a very new car, and I don't think this would be a usual occurrence -- not common enough for anyone to bother checking.

HOW TO CHECK for a rusty muffler:
Wait until it's cooled down after driving, then grab the tip and shake it. The rubber hangers will let you wiggle the exhaust enough for this. If something metallic has come loose, it'll rattle (and if it's water, it'll sound like water sloshing around).

Like I said, though, this would be very surprising on such a new car. My '86 Civic had its muffler rust apart on the inside -- but that was when it was maybe ten or eleven years old.

 

[Oliseles]

No, I don't think it's the gas tank at all.

Go drive it on the highway again (I believe you when you say that city driving is lots of idling and low-throttle driving), and try going around 100 km/h or so for at least 10-15 minutes. Then pull off somewhere, get out and listen right away, and I'm pretty sure you won't be hearing any gurgling.

Im pretty sure if its very humid outside or raining and therefore already gurgling like crazy, even if i get on the highway for a while the sound will still be there when i put it back into park and idle. When the sound is the loudest no matter what I do the gurgling continues. The only way to make the gurgling stop is to park it and leave it overnight (hoping its not raining or very humid the next day). But Ill definitly check next time. Thanks.

There's a slim chance that one muffler side has started to corrode inside.. but I seriously doubt it. The possibility comes from the car spending the first part of its life being driven from one side of the dealer lot to the other, which warms up the engine enough to make water, but never warms up the exhaust pipes (and especially the muffler) enough to prevent vapor from condensing inside. Besides, it's a very new car, and I don't think this would be a usual occurrence -- not common enough for anyone to bother checking.

HOW TO CHECK for a rusty muffler:
Wait until it's cooled down after driving, then grab the tip and shake it. The rubber hangers will let you wiggle the exhaust enough for this. If something metallic has come loose, it'll rattle (and if it's water, it'll sound like water sloshing around).

Like I said, though, this would be very surprising on such a new car. My '86 Civic had its muffler rust apart on the inside -- but that was when it was maybe ten or eleven years old.

When I got the car the outside of the exaust and the flanges already had rust on them so, in my case, and because of the history of the vehicle, rust could be an issue. Ill definitly check the exhaust like you said when the engine has cooled down.

Update
Today was sunny and dry.
I drove the car to work this morning
Same itinerary. Lots of idle. City driving.
Absolutely no sound this morning even at idle.
Tonight I drive back home and when i park home I get out of the car.
A litlle bit of gurgling. Just a little bit. Nothing compared to yesterday.
You can still hear it a little bit though. So now I dont know.
I have an appointment with my dealer may 1st and honestly i have absolutely no idea what to tell them...and from the look on their face monday they have no clue what the problem is...

 

[BarracksSi]

If it had rusted, you'd hear it ALL the time.

But because it's gurgling when it's humid (and/or cool) outside, I'm thinking that it's condensed water vapor.

 

[Oliseles]

If it had rusted, you'd hear it ALL the time.

But because it's gurgling when it's humid (and/or cool) outside, I'm thinking that it's condensed water vapor.

Ill tell exactly that to my dealer. I dont know what can be done though.
What can they do about condensed water vapor...change the exaust?

 

[Oliseles]

If it had rusted, you'd hear it ALL the time.

But because it's gurgling when it's humid (and/or cool) outside, I'm thinking that it's condensed water vapor.

Sunday night was raining like crazy. I drove on the highway and there was so much water. I wonder if water from the road could get inside the exaust and make the problem worst. The way the exaust tip is made it could easily pick up water from the road...

 

[BarracksSi]

What can they do about condensed water vapor...change the exaust?

Can't do much of anything except what I wrote in my first post: Don't idle so much, and drive more.

When the exhaust pipes and muffler are warm enough, any water boils away and evaporates. Idling for too long and spending all day at low load and low revs doesn't make the engine work hard enough to warm up the exhaust pipes.

The way the exaust tip is made it could easily pick up water from the road...

No. Exhaust fumes are constantly blowing out the tip.

 

[Oliseles]

One last question : how come it only does it when the engine is warm, never when i start the car and the engine is cold?

No condensed water vapor when i start the car and a lot after driving a little at low rev and idling a lot?

 

[BarracksSi]

One last question : how come it only does it when the engine is warm, never when i start the car and the engine is cold?

No condensed water vapor when i start the car and a lot after driving a little at low rev and idling a lot?

It takes time to build up enough liquid water to gurgle.

(idling is just wasting gas, too)

 

[Oliseles]

It takes time to build up enough liquid water to gurgle.

(idling is just wasting gas, too)

Well unless i wake up at night to go for a drive or a highway is built on my way to work i cannot drive ''more''. All I can think is to drive it in sport mode when i do...
Thanks for all your help BarracksSi!

 

[BarracksSi]

All I can think is to drive it in sport mode when i do...

Drive it like ya stole it!

 

[Oliseles]

Drive it like ya stole it!

Will do!

 

[Oliseles]

Hey BarrackSSi
When I have to idle can i put it in park, give it a little gas and make the car rev a little bit
Could that help a bit too?
Also i started using the L mode instead of using the brakes when i need to slow the car down
useless?
Im even tempted to drive it in L mode at low speed
I want to boil away any water in there so it evaporates
Will this help a bit?

 

[BarracksSi]

How long do you idle, anyway?

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