Exhaust clogged with ice?

I have a 2001 Santa Fe. I moved the car the other night from one parking spot to another. High temps those days were ~5 F. When trying to let it warm up the next morning, it started clunking through the exhaust system. The last time I heard that noise was 3 years ago when the exhaust clogged with ice, and in that case the exhaust manifold cracked and had to be replaced. I quickly shut the car off this time, but we aren’t supposed to get above freezing temps for a while.

Is this just ice in the exhaust system? Is this from starting the car for only a short period before turning it off for the night? The only thing I can think is that the rich start-up mixture creates more water vapor which quickly condenses on the cold exhaust. If so, next time I will be sure to take a trip around the block at least.

Is this common - or at least common with this make/model? Thanks for the help.

I’m sorry I can’t be more help with this except to pass along advise I’ve received that might be applicable. I was told that during short trips the exhaust pipes don’t get hot enough to evaporate the condensation in the exhaust system. This was explained to me when I was asking about storing a car for a long time and he recommended that I drive it at least 30 minutes before I park it to evaporate the water so my exhaust won’t rust as much.

The vapor pressure of water changes very little even if it’s cold enough for ice. I don’t think (I could be wrong) that enough water would have been created to cold your exhaust, and even if you had a good amount in there it would sublimate (got from a solid directly to a gas) fairly well.

Your exhaust was clogged with ice? Learn something every day, I guess. Water vapor is steam. If you pour liquid water on your exhaust, how quickly will it freeze? If you blow steam at it, how quickly will it freeze? Why isn’t this a common problem?

And what would keep it from going to liquid first?

I was saying while it was sitting overnight, the ice would evaporate maybe not all, but a good portion. It would melt if she started the engine and subjected it to heat…

I’ve seen ice in exhaust systems…but no where near enough to clog it…Just a light coating. This is caused by short trips…exhaust doesn’t heat up enough to burn the water vapor off (by-product of exhaust). Then when the car stops in very cold weather…the water vapor turns to water and freezes.

The ONLY other way I can think of this happening (although I’ve never seen it)…is a bad snow storm or ice storm with winds that will blow snow/ice into the exhaust. I’ve seen this on a house stove exhaust vent. The flapper that prevents this was broke.

While ice clogging an exhaust system seems improbable to me, you have already had a cracked manifold with similar symptoms. Ice could be building up somewhere in the system and freezing and causing problems. If you aren’t comfortable starting the car and driving it for 30 mins or more to warm up the exhaust and therefore melt and evaporate the ice; then have the car towed to a heated garage. Let it warm up overnight and then start it to see if the noise stays or goes away.

Engines crank out enough heat that I’d be surprised if the exhaust was icing up. I’ve never heard of this happening on any car, in any temperature. But since you said that this happened before, I guess anything is possible. Perhaps a flaw with the way that vehicle’s exhaust system is designed. Or you may have a deeper problem, like a partially plugged catalytic converter.

Is there any possibility of putting it in a heated garage or outbuilding to see if this makes the problem go away? Is the check engine light on at all?

The only time I’ve ever seen enough ice in an exhaust system to plug it was when the car was parked in water deep enough to seep into the holey system. Then it froze. We thought the non-start issue had to be electrical. Took a while to figure it out. Finally tried a vacuum test. Practically NO vacuum on cranking was the key.

I don’t think the pipes themselves are frozen through. The original sound I heard seemed more like ice shearing from the sides and becoming stuck somewhere near or in the muffler. The idea that the gas contained more water from condensation, a rich mixture at startup put more of this water in to the exhaust, and the short running time reduced the chance for this water to evaporate or be expelled seems completely plausible to me, but I’ve never seen it before this car either.

I doubt sublimation would have much effect in exhaust pipes - it typically takes reduced pressure to make solid water sublimate at a reasonable rate (ie, overnight).

Luckily I don’t drive to work, so this car can sit for a while. I just thought it strange that I’ve now seen this a couple of times. Wasn’t sure if others had experienced this as well - doesn’t sound like it. Thanks for the feedback. BTW, also thought it was interesting that Carveaholic assumed (wrongly) that I was female…

More than likely that’s what it is. I used to experience this from time to time in a '96 Sable I owned. After a new snow fall especially, driving on unplowed streets would kick up snow & ice around and on top of the exhaust sytem causing it to clunk against the floorboards. After driving awhile it would eventually heat up enough to melt it or cause the build up to fall off.

I’m inclined to believe your theory. A cold engine does put out a lot of moisture, and with the exhaust system at 5 degrees F the moisture condenses quickly on the surface. The metal exhaust quickly draws the moisture down below freezing. For most of us, we continue running the engine until the exhaust warms up enough to carry the moisture out and to warm the metal exhaust sufficient to, when combined with the hot exhaust gasses, eliminate most of the condensation, but if you’re just running the engine for a few minutes you can expect ice to form and remain in the exhaust. I’ve never personally heard of it breaking loose and clunking in the morning, but it makes perfect sense.

At 5 degrees F, it’s very common to be following a car and see condensation dripping out the tailpipe. Mufflers even have “weep holes” designed into them to allow condensation to drip out. At 5 degrees F that water could easily freeze if the engine is never warmed up.

And yes, water freezing to ice can easily create enough pressure to crack an exhaust. It can crack a boulder. And anyone who’s had pipes explode can testify to the amount it expanded the pipe before exploding it.

I find your theory very viable.

I myself cannot picture how enough water can be contained (meaning filled up) in an exhaust manifold to allow for freezing to cause cracking. I do know exhaust manifolds can crack with no freezing event experienced at all. We are quickly moving into an area where we are saying the most complex explaination is the most likely one, this is an error in logic.

I admit that I too have a hard time envisioning it, but since he said he’d experienced it I’ll assume there’s a cavity in the design that can entrap water. It could even be a casting sprue mark that leaves a cavity.

Here I am looking for advice, and t turns out that I will be able to provide some. seeing the responses to this question, I can see that what I can provide is a lot of answers.

I live in cold Minnesota, last winter I backed up and parked with my rear end in a snow bank. (Honda Odyssey).

When I took of the next morning, my engine was wheezing, thinking there was something wrong under the hood, I parked and when I went to my back end to get some tools, I saw that my tail pipe was a plug of solid ice. I chipped it out with a hammer and screw driver.

What must of happened was when I backed up into the snow bank, the tail pipe stuffed up with snow. then the snow melted, and refroze as a chunk of ice blocking the exhaust.

Why I came here was just last night it has happened to me again. Except this time, I have backed up in a drift, but pulled away. The snow must have melted, and the water flowed into the exhaust system more. Now the flow of gases has slowed, creating a dam. It backed up so much that the muffler became a solid block of ice. I have spent hours with a propane torch heating up my muffler, and now am getting flow.

I idle my car very often, the thing is I am a homeless guy, and my car is my heated home. I guess now when I run my car at night, instead idling it I will need to drive it around a couple of blocks.

Another thought that I had, was that even tho the ice may not have blocked the exhaust completely, since the flow is restricted, the gases have to flow through a smaller opening. Just like a refrigerator compressor, when gasses get compressed it creates a colder temperature, this would accelerate the freezing.

You’ll want to be very careful living out of your car that your exhaust does not become clogged. Make sure you keep your tailpipe clear of snow. You could become asphyxiated by carbon monoxide.

Thank you for the concern. I was of course very concerned about this. Even when it’s operating correctly i keep it on my mind, finding the right parking position etc. A week does not go by up here without another tragic story of travelers snowbound and asfixiated.

Just don’t back it into a snowdrift.

If you’ve got enough skills to get to the library or wherever to get internet access, and to get fuel for your vehicle, you should be able to find some organization that will give you a sleeping bag. Get your Honda Odyssey self to work and find the resources that are available to you!