Welcome to the Corvette Forums at the Corvette Action Center!

exhaust water



when I first start up my '77 vette, a small amount of water shoots out both exhaust....after warm-up and idle speed is reduced, this stops....is this anything to be alarmed about? Thanks, Keith:eyerole
No worry

Keith ,
Water is probably most prevelant after the motor has completely cooled, and you restart it, right?

This is a normal issue for cars with mufflers located at the far end of the exhaust chain. As the hot exhaust cools it actually sucks some cooler (and moister) air back into the mufflers (which are located at the very rear of the car.) This large volume chamber then acts as a condenser and VIOLA! a little water collects in the system.

After you start the car it blows out and is completely gone within a few minutes.

Some cars actually have a pinhole in the lowest point of the muffler to let condensate drain out (in hopes of retarding the inevitable Rustout.

Now a LOT of water could actually be a blown head gasket, but I'm sure you would be able to tell the difference.

Don't worry! Enjoy your ride!~

Kieth, What Rick said. But, also this is even more prevelant with a car that has a catalyt converter, due to the much higer exhaust temp..............Steve

Me too.

Thanks guys, now I can sleep better....condensation buildup is the problem for sure as this only happens when I start it up after a complete cool-down....and it is only a small amout of water.....Thanks again for the relief...Keith:w
My 69 coupe spits water only out of the passenger side pipe for the first 10 minutes or so after startup from cool. No catalytic converter to add heat level. It sounds as though I have an exhaust leak too. Is it time to panic?
Don't panic yet.:eek

First of all, it is possible that a difference exists in the routing of your ehaxust pipes that can cause water to buildup in one side or the other of the exhaust system after cool-down.

Especially if the pipes are routed in such a way as to create large areas that water could be trapped. This is often the case in tight fit cars where the motor takes up most of the room under the hood and in the cross members. I have also seen shade tree mechanics do some pretty strange routing jobs in order to get the
wrong mufflers to fit.:r:(

Most importantly:
1. Are you noticing a mysterious water loss in the radiator?
2. Have you had problems in the past with one side of the exhaust system rusting out much sooner than the other?
3. Are spark plugs on that side noticeably more fouled than the others?

These are pretty good indications of head leaks and if you aren't seeing them, you are most likely okay. :)

Since every car I've ever owned has done that, I'd worry if it didn't;).

- Eric
Boy, oh boy are there some strange explanations on this thread.

Water, in the form of steam, is one by-product of combustion. When the car is first started, the exhaust system is cold enough that the steam condenses during its trip through the system. The result of liquid water dripping out of the exhaust while the engine warms.

Once the temp. in the exhaust system gets higher, the water remains as vapor or steam until the exhaust is expelled to the atmosphere.

The water vapor IS NOT a result of condensation or moisture getting sucked into the exhaust during the previous cool down---I just *have* to ask: do you guys make this stuff up??
Our 3500 95 truck with the 454 EFI gets a nice spit of dirty foul black water out the massive exhaust pipe for a few seconds right after it starts.

Now, I was under the impression that his is because Chevrolet installed a secret exhaust cooling system. See, most people don't know about this and it has been kept a secret for years. The tech guys explained it away as moisture condensing, but really it is a hsp additive. See, water is pulled in via the washer bottle. That is why it always seems like it is empty right after you fill it. Then, it is injected by the A.I.R. pump into the exhaust. The exchange of the water into the exhaust drops the temps right at the exhaust valve and increases velocity.

This results in a 10-15% increase in power. Ford has yet to figure this out, and any water out of those pipes is from a faulty head gasket.

Okay Hib, I am obviously making this up:L :L :L It sounded good for at least a line or two.
Hey, Chris

Does Chevy have a sticker for that secret exhaust system? I, like many others, am always looking for ways to increase my power, and adhesive stickers seem to be an affordable and easy way to do that. :D

They have a sticker, but the moisture from the water tranfer makes them peel off.

A good restoration specialist can duplicate the left over adhesive markings on the firewall for authenticity.
Thanks, Chris

I'll call Ecklers and see if they can put me in touch with somebody.

On the other hand, this may be a topic/question for the "other" board. :D I just may have to register so I can ask.

Racer78 said:
I have heard of water staying in mufflers and pipes and causing them to rust out. Especially in the rear of the car.

Is this a myth? If true what causes this?

It's twue, it's twue.
It happens most often with mufflers that don't have drain holes or have had the holes plug up.

I have also been told over the years the reason with back half of the exhaust system rusts first is it doesn't stay as hot and i quess hense does not really dry out as well?

I think the major factor in rust out is quality of the system. I have had several new car's exhaust systems last 7 or more years, while the replacement stuff usally don't last like that. :)

I'd say the above is partially true but would add that two other significant factors in exhaust corrosion are:
1) there are other combustion byproducts that combine with moisture to produce acids that enhance and accelerate corrosion.
2) in areas where there's a lot of bad weather, corrosive agents are introduced to the outside of the exhaust and that enhances and accelerates the corrosion process even more.

Okay Hib, I am obviously making this up It sounded good for at least a line or two.

Too much time you *your* hands.
Hib is da man!

- Eric
I agree with Hib's observations. I might also add that some people, especially collectors, like to go out once a week or so, start the Vette, back it out of the garage, let it idle for 10 minutes or so and then put it back in the garage. They figure they are keeping the battery charged - keep it from going bad. Problem is, the exhaust system does not get hot enough to turn the water to steam. More water = more rust. If you have a 5 minute drive to work, as opposed to a 30 minute drive to work, you will be replacing your exhaust system, especially from the cat back, in a relatively short time.


Corvette Forums

Not a member of the Corvette Action Center?  Join now!  It's free!

Help support the Corvette Action Center!

Supporting Vendors


MacMulkin Chevrolet - The Second Largest Corvette Dealer in the Country!

Advertise with the Corvette Action Center!

Double Your Chances!

Our Partners

Top Bottom