# Does it damage cars when going through huge puddles? **URL:** \ **Category:** Factual Questions\ **Created:** [December 18, 2004, 6:27pm UTC](https://boards.straightdope.com/t/does-it-damage-cars-when-going-through-huge-puddles/280546 "2004-12-18T18:27:46Z")\ **Posts on this page:** 13\ **Page:** 2
**Author:** ![drachillix](https://avatars.discourse-cdn.com/v4/letter/d/48db29/32.png) [@drachillix](https://boards.straightdope.com/u/drachillix)\ **Post date:** [December 18, 2004, 11:59pm UTC](https://boards.straightdope.com/t/does-it-damage-cars-when-going-through-huge-puddles/280546/21 "2004-12-18T23:59:52Z")
> [@ParentalAdvisory](#): > > Water in the cylinders can definitly cause permanent damage if your intake is exposed to a great deal of water. As a more specific side note to this, the expansion ratio from water to steam is something like 1:1700 So if 10 cc’s of water somehow made it to a cylinder it would flash into 17,000cc’s of steam at atmospheric pressure, creating a hefty pressure spike in the affected cylinder. If it wasn’t enough to blow the head gasket the extra compression or earlier compression would exert alot of force on the connecting rod and or crankshaft making for some ungodly strain on the engine. ---
**Author:** ![mike1dog](https://avatars.discourse-cdn.com/v4/letter/m/ba9def/32.png) [@mike1dog](https://boards.straightdope.com/u/mike1dog)\ **Post date:** [December 19, 2004, 3:31am UTC](https://boards.straightdope.com/t/does-it-damage-cars-when-going-through-huge-puddles/280546/22 "2004-12-19T03:31:21Z")
I doubt that the water flashes into steam. You just can’t compress water. ---
**Author:** ![Anachronism](https://avatars.discourse-cdn.com/v4/letter/a/e56c9b/32.png) [@Anachronism](https://boards.straightdope.com/u/Anachronism)\ **Post date:** [December 19, 2004, 12:23pm UTC](https://boards.straightdope.com/t/does-it-damage-cars-when-going-through-huge-puddles/280546/23 "2004-12-19T12:23:55Z")
> [@drachillix](#): > > As a more specific side note to this, the expansion ratio from water to steam is something like 1:1700 So if 10 cc’s of water somehow made it to a cylinder it would flash into 17,000cc’s of steam at atmospheric pressure, creating a hefty pressure spike in the affected cylinder. If it wasn’t enough to blow the head gasket the extra compression or earlier compression would exert alot of force on the connecting rod and or crankshaft making for some ungodly strain on the engine. Actually the problem is due to the fact that water is not compressible. When the piston tries to comes up but runs into water that can not be compressed something has to give. In my experience most modern cars have plastic shielding below the engine that seems to do a pretty good job of protecting the engine. ---
**Author:** ![ParentalAdvisory](https://avatars.discourse-cdn.com/v4/letter/p/53a042/32.png) [@ParentalAdvisory](https://boards.straightdope.com/u/ParentalAdvisory)\ **Post date:** [December 20, 2004, 2:37pm UTC](https://boards.straightdope.com/t/does-it-damage-cars-when-going-through-huge-puddles/280546/24 "2004-12-20T14:37:56Z")
> [@drachillix](#): > > As a more specific side note to this, the expansion ratio from water to steam is something like 1:1700 So if 10 cc’s of water somehow made it to a cylinder it would flash into 17,000cc’s of steam at atmospheric pressure, creating a hefty pressure spike in the affected cylinder. If it wasn’t enough to blow the head gasket the extra compression or earlier compression would exert alot of force on the connecting rod and or crankshaft making for some ungodly strain on the engine. I’m familiar with this, it’s sometimes known as “vapor lock”. But the situation also works with raw fluids (water, gasoline), and no steam. So it can happen when your engine gets flooded with fuel, and it cannot compress all of the fuel. Next thing you know, you have some bent connecting rods, push rods, broken piston rings, etc… Anything physically attatched to the piston is at risk of damage. Pretty much what **Anachronism** stated. ---
**Author:** ![Madd\_Maxx](https://avatars.discourse-cdn.com/v4/letter/m/5f9b8f/32.png) [@Madd\_Maxx](https://boards.straightdope.com/u/Madd_Maxx)\ **Post date:** [December 20, 2004, 4:34pm UTC](https://boards.straightdope.com/t/does-it-damage-cars-when-going-through-huge-puddles/280546/25 "2004-12-20T16:34:51Z")
Regularly driving through water higher than your axle bearings can lead to the grease in said bearings needing to be replaced/repacked more frequently lest bearing damage occur. I think some older transmissions have “seep” holes to allow water to drain, if the seep hole becomes clogged the water can become trapped and damage the transmission. These problems are more frequently associated with off road driving, specifically water crossings, but if you live in Seattle and have a tendency to hit every single puddle you can get your tires on, then they might apply to you. ---
**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\ **Post date:** [December 20, 2004, 5:10pm UTC](https://boards.straightdope.com/t/does-it-damage-cars-when-going-through-huge-puddles/280546/26 "2004-12-20T17:10:12Z")
> [@ParentalAdvisory](#): > > I’m familiar with this, it’s sometimes known as “vapor lock”. But the situation also works with raw fluids (water, gasoline), and no steam. So it can happen when your engine gets flooded with fuel, and it cannot compress all of the fuel. Next thing you know, you have some bent connecting rods, push rods, broken piston rings, etc… Anything physically attatched to the piston is at risk of damage. Pretty much what **Anachronism** stated. Ahh, no. Vapor lock is when liquid gas gets too hot on it way to the fuel pump and boils in the gas line. The fuel pump (mechanical back in the days of carbs) could not pump vapor only liquid. The gas vapors in the fuel line caused the pump to stop pumping, the carb then “ran out of gas” even though you might have 10 gallons in the tank. Obviously, this was a greater problem on hot days under sustained loads (climbing hills for instance) The cure for a vapor locked car was to pull over and open the hood, and allow everything to cool down. What you are thinking of is hydraulic lock. That is where a liquid gets into the cylinder, and since liquid are not compressible, bad things happen when the piston comes up to compress it. In minor cases, the connecting rod gets bent, and some very interesting noises can result. In more severe cases, the engine will stop turning completely and be locked. In very very severe cases, pistons can be broken. The water will not flash into steam, as there is not enough heat in the engine to do that… Damage comes from trying to compress a liquid. **Madd Maxx** I have no idea what seep hole you might be talking about. Any hole that was on the bottom of the trans case to allow water do drain out, would also allow all of the lube oil for the trans to drain out. This would be considered a bad thing, even if you did not drive through a puddle. There are vent holes on the top of transmissions (and differentials) to allow pressure equalization, which can allow water to get into the case if the unit is submerged. I can guarantee you that there is not a hole on the bottom that is open all the time to drain water. ---
**Author:** ![LouisB](https://avatars.discourse-cdn.com/v4/letter/l/dfb087/32.png) [@LouisB](https://boards.straightdope.com/u/LouisB)\ **Post date:** [December 20, 2004, 5:59pm UTC](https://boards.straightdope.com/t/does-it-damage-cars-when-going-through-huge-puddles/280546/27 "2004-12-20T17:59:42Z")
> [@KP](#): > > I have experienced dirt and mineral glazing on alternator brushes and contacts afte driving through this kind of deep road water. Though this was quite a few years ago, I don’t believe alternators have changed. > > Sadly it was on Friday night during a holiday weekend getaway. It being a holliday weekend, none of the local garages would be open until Tuesday, and from what we heard, they would be swamped for a couple of days, due to all the vacationer’s breakdowns We were lucky that another local couple was there. They followed us home, jump charging our battery every 50-75 miles or so. This took longer than w we planned, and delayed us enough that the sun set, so we were forced to give it a long recharge every 20 miles of the last leg, due to headlight drain. > > Everyone we spoke to sold us we’d need to replace the alternator, but I couldn’t get an appointment for two days. In a moment of lunatic genius, I jump-started the car, then ran clean water through the alternator through a garden hose for several minutes (I told you it was lunacy). This apparently cleaned off the contacts, because the problem was fixed, and the alternator lasted years after that. > > I’m not recommending this as a repair or a safe way to drive home (I was young and stupid, and I don’t know what damn fool thing someone else might do while trying it). I’m only offering it as evidence that the problem was indeed due to dirty brushes/contacts. Otherwise, flushing a running alternator with clean water would only have made things worse. So far as I know, there are no brushes and no contacts inside an alternator. The main point of an alternator was to eliminate the problems that resulted from the brushes in a generator going bad, and to eliminate the external, bulky, not-always-reliable, and easily damaged voltage regulator. An alternator’s output voltage is rectified by diodes resident in the alternator case. There are no brushes in an alternator. ---
**Author:** ![LouisB](https://avatars.discourse-cdn.com/v4/letter/l/dfb087/32.png) [@LouisB](https://boards.straightdope.com/u/LouisB)\ **Post date:** [December 20, 2004, 6:07pm UTC](https://boards.straightdope.com/t/does-it-damage-cars-when-going-through-huge-puddles/280546/28 "2004-12-20T18:07:37Z")
> [@mike1dog](#): > > I doubt that the water flashes into steam. You just can’t compress water. In the early days of drag racing, water injectors were often used to provide a little boost to the compression inside the cylinder. I admit that the water injected was a minute amount, but the resulting steam did increase the compression and that, in turn, delivered a stronger thrust to the piston. Street racers sometimes used their windshield washer system in lieu of injectors. Water in any sort of volume inside a running gasoline engine is not good—bent rods are probably the least of it. ---
**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\ **Post date:** [December 21, 2004, 12:02am UTC](https://boards.straightdope.com/t/does-it-damage-cars-when-going-through-huge-puddles/280546/29 "2004-12-21T00:02:28Z")
> [@LouisB](#): > > So far as I know, there are no brushes and no contacts inside an alternator. The main point of an alternator was to eliminate the problems that resulted from the brushes in a generator going bad, and to eliminate the external, bulky, not-always-reliable, and easily damaged voltage regulator. An alternator’s output voltage is rectified by diodes resident in the alternator case. There are no brushes in an alternator. Alternators do have brushes, and slip rings. The slip rings being smooth do not wear the brushes, the way a segmented comutator does. Therefore the brushes do not wear out anywhere as quickly as they would on a DC generator. If there were no brushes, then how would you get current into the rotor to create the magnetic field? 😕 Look [here](http://www.autoshop101.com/trainmodules/alternator/alt110.html) for a picture of some alternator brushes ---
**Author:** ![LouisB](https://avatars.discourse-cdn.com/v4/letter/l/dfb087/32.png) [@LouisB](https://boards.straightdope.com/u/LouisB)\ **Post date:** [December 21, 2004, 1:05am UTC](https://boards.straightdope.com/t/does-it-damage-cars-when-going-through-huge-puddles/280546/30 "2004-12-21T01:05:14Z")
\*\*Rick,\*\*I stand corrected and apologize for my error re alternator brushes. I guess it’s a very good thing that I no longer follow the mechanic trade. Thanks for the correction. ---
**Author:** ![Madd\_Maxx](https://avatars.discourse-cdn.com/v4/letter/m/5f9b8f/32.png) [@Madd\_Maxx](https://boards.straightdope.com/u/Madd_Maxx)\ **Post date:** [December 24, 2004, 3:44am UTC](https://boards.straightdope.com/t/does-it-damage-cars-when-going-through-huge-puddles/280546/31 "2004-12-24T03:44:15Z")
> [@Rick](#): > > \ **Madd Maxx** I have no idea what seep hole you might be talking about. Any hole that was on the bottom of the trans case to allow water do drain out, would also allow all of the lube oil for the trans to drain out. This would be considered a bad thing, even if you did not drive through a puddle. There are vent holes on the top of transmissions (and differentials) to allow pressure equalization, which can allow water to get into the case if the unit is submerged. I can guarantee you that there is not a hole on the bottom that is open all the time to drain water. :smack: that’s what I was talking about the “vent holes.” Seep holes are on water pumps. right idea, wrong word. Still having to drain your transmission because it got flooded with water would still suck. ---
**Author:** ![Muffin](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/muffin/32/4341_2.png) [@Muffin](https://boards.straightdope.com/u/Muffin)\ **Post date:** [December 24, 2004, 9:08am UTC](https://boards.straightdope.com/t/does-it-damage-cars-when-going-through-huge-puddles/280546/32 "2004-12-24T09:08:36Z")
Sometimes thar be monsters. Today we settled a claim for a few hundred thousand. Our client was injured when the vehicle in which we was a passenger hit a submerged rock. ---
**Author:** ![Muffin](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/muffin/32/4341_2.png) [@Muffin](https://boards.straightdope.com/u/Muffin)\ **Post date:** [December 24, 2004, 9:15am UTC](https://boards.straightdope.com/t/does-it-damage-cars-when-going-through-huge-puddles/280546/33 "2004-12-24T09:15:19Z")
If you are in the habit of crossing water but don’t go deep enough to get water into the air intake, you still should consider making snorkles for the much lower differential and transmission vents – all it takes is some flexible tubing and some clamps. [Previous page](https://boards.straightdope.com/t/does-it-damage-cars-when-going-through-huge-puddles/280546.md?page=1)