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Civic stalled in water, now its thrown a rod

I’m writing to figure out what happened, how to avoid doing it again, and whether the repair shop owes me an engine. My 2006 Civic stalled in 8" of water 1 1/2 weeks ago. I pushed it out of the water, and it started after about 1/2 hour. It was running a little rough and the “malfunction” light was on (which the manual says means a problem with a pollution control sensor). The air cleaner was dry, and the oil looked clear (as in not “milky” as it would if water got in).

The Honda dealer couldn’t even look a it until next week, so I took it to Firestone. They did a full engine diagnostic, replaced the Oxygen sensor, changed the oil (it was due anyway) and recommended that I replace the Mass Air Flow sensor soon. That was yesterday.

Today the car threw a rod. I haven’t heard how much a new engine will cost me yet. What happened? Is this not something the Firestone folks should have been able to spot?

This is just guess-work, but I think it is likely that you bent a connecting rod when water was drawn into the cylinders. That bent rod later went through the side of the engine block.

The moral of the story is–DO NOT drive a car into 8" inches of standing water.
I do not think that Firestone has any liability here.

NO, I think this ones on you.

Don’t point the finger at someone else because of your error in judgment.
The rough running could have been caused by a bent and damaged connecting rod due to water (which is not compressible) being inhaled into the engine and at some point the damaged rod will give up.

It’s called thermal shock.

If you take a hot engine and emerse it in a cold environment it can cause unloaded stresses in the casting of the engine block to load. This causes the bore alignment to crank shaft and cylinders to become misaligned, and somethings got to break.

This is NOT a 350 Chevy engine.


When the car stalled the damage was already done. When you splashed a large amount of water into the air cleaner it went into whatever cylinder had the intake valve open at that time. The engine was still turning and the valve closed with the piston coming up and tried to compress water which it can’t so the crankshaft was still pushing up on the bottom of the rod and it bent. It was running rough when you got it restarted because it was running on three cylinders and forcing the damaged connecting rod around until it broke. The you took the car to a national chain which is not really equipped to do this kind of diagnostic work. To avoid doing it again don’t drive into standing water and don’t take a car with engine problems to tire or muffler chains. It would have been a lot cheaper to rent a car until the dealer could deal with it and possibly save the engine although it would not have been a cheap fix.

After the car had stalled and pushed out of the 8" of water, the spark plugs should have been removed before attempting to start the engine. After the plugs were removed and the ignition and fuel pump disabled, the engine should have then been cranked over to dispell any water in the cylinders. Then some oil should have been squirted into each cylinder and the engine cranked over again to distribute the oil. Then the sparkplugs can be reinstalled and the engine started. An oil change would help at this point.

What you experienced is called hydraulic lock. A liquid can’t be compressed. I’m surpised that you were able to start the engine at all. My guess is that there was water above one cylinder and the rod bent as you attempted to crank it. Eventually the water was forced out through the exhaust valve, but at this point the damage was done.

OK, I shouldn’t have been in the water (we were trapped in a line of traffic during a VERY heavy rainstorm in New Orleans), I should not have restarted the car, should not have gone to Firestone, and this one’s on me. I’ll accept that.

I’m a physics teacher, I like to understand things. As technical matter, wouldn’t water have shown up in the oil? It didn’t come in through the air cleaner, as it was dry, and the water never got that high anyway. Can it come in the back way via the muffler and the cylinder’s exhaust valve?

The moral of the story is–DO NOT drive a car into 8" inches of standing water.

Worth repeating!

You’re right. The circumstantial evidence doesn’t PROVE anything. The rod knock, if that is what it is, could be purely (99%) coincidental.
The proposed PROOF that hydrostatic lock occurs, is that, SOMETIMES, it does occur after a vehicle runs through standing water (even of modest depth).
You could take your car to a mechanic who will fill out a diagnosis stating that “hydrostatic lock caused engine damage”, and submit a claim to your car insurance, or property insurance company.

I’ve been thinking about this situation and have a couple of questions:

  1. Did the rod go through the block or did the rod fail and the engine start knocking?
  2. When you attempted to start the engine after it was pushed out of the water, did it turn over? If it did, your problem was not hydraulic lock. If it would not turn over, then it may have had hydraulic lock.
  3. After Firestone worked on the car, did the engine run as it should?
  4. It seems that if water did get into the engine, it would have had to come through the tailpipe. I’m not certain, though, that having the tailpipe underwater would stop the engine. Our boatmotors had underwater exhaust.

If you didn’t detect water in the oil, I would doubt that this caused a rod bearing failure. I had a cracked motor block once on my 1947 Pontiac. Considerable coolant mixed with the oil, but I didn’t have a bearing failure.

If the engine was hydraulically locked, I don’t think you could have started the engine half an hour later.

I don’t know what your problem is but I just do not believe it was hydraulic lock.

This sort of damage is quite commom. It doesn’t take much water to hydrolock an engine. The space into which the fuel air mixture is compressed is probably only a couple or three table spoons in capacity. Add a table spoon of water, and you have real problem. I will admit that I’ve never seen a Civic damged by only 8" of water, but I’ve seen several cars damaged by 12". Are you sure you didn’t drive it thru a dip at a corner? Yes, the air filter was dry when you looked at it, but it may have only been really wet for an instant. Then it had a lot of air drawn thru it to dry it out. The reason the MAF sensor needed to be replaced before the rod broke is the same water that hyrdolocked the engine.

Looking on the bright side, if you have comprehensive insurance on this car, it will probably be considered a “total”. Now you can go car shopping with someone else’s money. If you don’t have comp insurance, look at for a good used engine near you.

I’m puzzled by almost every reply to this one. How does 8 inches of water even reach the frame, much less stress the metal of the engine because the engine’s so scary hot? How does the water splash up about 3 feet and guide itself into the airfilter, which you said was dry (folks missed that, it seems).

Is the only reason cars ever throw a rod water in the engine?

We have been assuming that water got above a piston causing hydraulic lock. However, gasoline in its liquid form can not be compressed. I wonder if the ignition failed at least on one cylinder and enough raw gasoline was pumped in to cause a hydraulic lock. I have experienced hydraulic lock with lawmmower engines when I have tipped the mower with the carburetor up and the gasoline got above the piston. When this happened, I couldn’t turn the engine over. The cure was to remove the spark plug and turn the engine over to expel the gasoline.

DWAR09, you had better take the car to a mechanic, I don’t believe you are going to get a sensible answer here.

There is a lot of missing info that the OP could have provided, but based on what they did provide the answers (theoretical though they be) are fine.

Mileage on car, any engine noises present, symptoms while trying a restart AFTER it was pushed out of the water, any vibration present after leaving Firestone, etc. are things that could help in formulating an answer.

The water is said to be 8" deep. A moving car is going to push that water ahead of itself and cause the water to be far deeper than 8" so it’s entirely possible for the engine to inhale water; and it doesn’t take much water to hydrolock an engine. A mere handful of water can do it.

I don’t know where the air inlet is that leads to the air filter on a Civic. I know many air inlets are down close to the ground at the front of different cars. The engine creates a great amount of suction as it runs. I have personally bought and replaced engines on eight Tauri with this same malady. (Search my earlier Taurus airbag post. The engine in the donor car I spoke of is going into another Taurus that was hydrolocked in this fashion.) Saabs are apparently another brand that is prone to this situation. I’ve also seen it on Mercedes cars. Tauri draw air in about a foot above the roadway. That should be high enough, but if one is driven into eight inches of water and meets another car causing a wake, they can swallow water. Same thing can happen when one hits a dip at a corner. Suddenly the water is over 12" deep. None gets into the interior, but a tiny amount gets into the engine.

Note that none of us here have seen your car. We’re giving you our best guesses from afar. You need to have a professional mechanic, or perhaps insurance adjuster, look at it.

To answer several questions about symptoms, including yours, there was no knocking sound prior to throwing the rod. The car was not running any smoother after replacing the oxygen sensor, changing the spark plugs and a minor tune-up.

The hole produced by the rod is in the bottom of the engine. I didn’t crawl under (in the spreading pool of nice clean, brand new synthetic oil) so I don’t know if it came through the oil pan or not. There was a loud bang sound, then a sound like something metal dragging under the car. I pulled over, and found 8 or 10 aluminum pieces of engine in the street and under the car, none bigger than a couple of inches across. I did not look at them in detail, but one had a nice smooth curve on one side that could have been a cylinder wall.

My insurance (USAA) will have an adjuster look at it as soon as they can. There are so many claims for water damage in New Orleans after the wettest December in decades (26+ inches!) that they can’t promise when that will happen. I don’t have a “trusted mechanic” to look at it, and AAA will only pay for one tow per breakdown, so it’s going to sit at the Firestone place for now.

Thank all of you (even the ones who figured me for an idiot) who responded.