Watching the major flooding in Calgary on TV got me wondering about something. I saw some fire engines going through fairly deep water (at a glance it looked like it was up to their floorboards). Are fire engines any more immune than other large vehicles to getting their engines drowned if they go through too much water? What about rescue trucks? (don’t know if that’s the right name; like big cube vans with lots of cubbyholes for rescue equipment).
The main issue with a lot of vehicles is that their exhausts are low on the body- go into deep enough water and the backpressure stalls the engine out.
Most large emergency vehicles have the exhaust pipes sticking up, as do most military ones- they can go into water nearly as high as the air intakes if need be.
Even ones without vertical stacks, your average piece of city fire apparatus is like 14"-16" off the ground. In a city, that is a lot of standing water. Ones in remote areas with offroad capabilities are even higher.
Lets just say Calgary has A LOT of standing water in a number of areas today! :eek:
http://boards.straightdope.com/sdmb/showpost.php?p=16402580&postcount=1440 just to indicate what A LOT of standing water means.
The engines, along with pretty much everything else in a modern fire engine is pretty high off the ground. Most large vehicles are the same height, though. A typical tractor trailer could drive through similar depth water with similar result, they just don’t have a reason to do so.
I wouldn’t be all that concerned with the engine (intakes and exhausts are often fairly high). The exhaust is not usually a vertical stack on most fire engines, it comes out behind the cab under the frame rails. Its still a foot or more up. I’ve never submerged my trucks’ exhausts, so i couldn’t say if the truck gets grumpy with the exhaust under water.
I’d be more concerned with the electrical system. Putting water to the floorboards is asking to put your batteries under water, along with the wiring harnesses. Lots of stuff to go wrong under there, and the last thing you want is a truck disabled in the water.
Normally a vehicle designed to go underwater has a diesel engine, (as the ignition leads for petrol engines must not get wet.), and a snorkel for air intake.
eg RangerRover, Landcruiser may have a snorkel for air intake, but not a raised exhaust (they don’t stall just because the exhaust is underwater. But they are hard to start if they have set stalled in water… and the exhaust filled with water… )
Here’s a firetruck going almost underwater… the driver was almost flooded out of the cabin..
If a flood looks as if it might be higher than your exhaust, then use a low gear and drive slowly with high revs to keep the water out. Many people come to grief because they drive fast and cause a bow wave that floods the engine.
Car drivers also don’t realise that cars are fairly waterproof. This means that once the water level gets above the floor, they start to float - if they are fording a river, they will soon be swept sideways.
Thanks guys!
The exhaust isn’t a problem or no one would be able to put a boat in at a boat ramp. It will just sit in the water and bubble. The electric system isn’t that vulnerable to freshwater either. The air intake is the main thing. As long as the intake is above water, you can, in theory, drive many vehicles like a submarine. Some vehicles may have certain vulnerabilities that prevent it though. For example, 90s era Mazdas had cheap little rubber boots over the spark plugs that wouldn’t keep a good splash from a mud puddle out, I’m sure they’d die in deep water pretty quick. And I know a guy whos Mercedes crapped out because one of the computers was placed where it wouldn’t get splashed by water, but wasn’t actually waterproof. It got wet somehow and died.
The vehicle may come down with a lot of problems afterwards too, depending on it’s design. The differentials and transmission may have vent tubes that are lower and you may get water in them.
Floating is a problem, like bob++ said. And even if you aren’t floating yet, the pressure that moving water puts on the side of a vehicle can sweep it away too. I think a couple inches of moving water can sweep away some cars. And you don’t know what’ sunder that water either. Is it the road or a big hole? Even if the vehicle is a submarine, it’s not a good idea to drive in water.
I love how he had the wipers on while underwater.
With that said that was a dumb move by the driver. There is no way to tell the depth of the puddle from the top.
Another 18" or so and the driver would have drowned.
I saw video of this years ago but my google-fu is lacking today so I can’t even find a picture, but it was a test run in … probably the 1950s. Color footage, tinted that blue that filming underwater in a swimming pool gets. There was a guy in scuba gear driving an army 2 1/2 ton truck, completely underwater.
As I recall, if you hook a diesel engine up to liquid oxygen, not only does it not need a snorkel to breathe, the exhaust doesn’t blow bubbles.
Wouldn’t it be a big problem if the radiator fan hit the water? I mean, that’s a lot of resistance. I could see the possibility of broken fan belts and such.
Well if has a fan clutch the fan will probably just stop. If not with all that water the belt would just slip. Water will act like a lubericant.
um. Why wouldn’t there be exhaust bubbles?
I would wonder whether the exhaust wouldn’t blow bubbles because it wouldn’t have a chance to before the engine went KABOOM!.
First off its not a good idea to drive through deep water. TBS if you must and that happens one should wade through using all cautions that are prudent such as very slow moving etc.
Then if water is deep enough that the bumper is going to be in the water you can bet the drive belts will also be submerged and if so and one must cross and I have been in that situation, the drive belt should be removed and reinstalled as soon as the crossing is made.
The drive belts will carry a lot of water up into the engine compartment and could cause a stall. If I should ever have to drive through moving water I would consider opening doors to counter being washed off track.
Brakes will not work at all until they dry so ride the brakes right away after crossing and water over 4 inches deep.
When I drive on frozen lakes I keep doors open and windows open and I do not wear the seat belt.
A tearable tragedy a few years back where a baby secured in a infant seat died when the parents couldn’t get to baby when their vehicle broke through the ice on Lake of the Woods
And here also,
Here is some common sense info on car in water emergency’s
Here is the link to car in water emergencys
The Fire engine in the 11 ft. flood waters was a special designed apparatus built for those kind of situations. It certainly had a snorkel like a lot of military vehicles.
And Rick he only had the wipers on intermittent! 
I don’t know. But that’s what I was told: diesel engines running on liquid oxygen don’t produce bubbles underwater. I guess somehow the exhaust dissolves into the water better.
Are there vehicles with a diesel/liquid oxygen engine?
After WWII, diesel subs did play with liquid oxygen, but piped directly it would blow up the engine, plus it would take a lot of oxygen to run the thing, so they mixed it with scrubbed exhaust gas. The whole system was closed, the exhaust went to the intake, and somewhere in between a little liquid oxygen was added. So a design like that would have no bubbles because it doesn’t expel any exhaust, it pipes it right back into the engine. That may be something like what you heard.