Knockig after getting flooded


I recently dove through a large puddle of water and my car stalled out when the water splashed on it. When the car finally started back up it had a really loud knocking sound to it. I have checked the ignition and oil for water. I see no signs of water that got in the engine anywhere. the faster the car goes the quieter the noise gets and the slower or at stand still the noise is unbelievable. Can anyone explain what has happend and how i go about fixing the problem. it is a 2001 plymouth neon


Id probably have to say that you got water in the oil and its not enough to show on the dipstick. It may have thinned the oil enough to make it unsafe to drive any more until you change it. You may do some serious damage to your engine if you dont at least try this before you drive the car again. These small 4 cylinder engines cant take too much abuse before they finally quit. Then you’re looking at a few thousand dollars maybe to get a new engine put in your car. Spend the $25 or so to change your oil then go from there.


Nope, you’ve probably hydrolocked the engine, at least momentarily. I’ve seen it MANY times. What happened was you sucked water directly into one or more of the engine’s cylinders. Water simply won’t compress like air. You have at least one bent connecting rod. Sorry, but the engine is probably ruined. If you have comprehensive insurance coverage, it should cover your accident. They can’t raise your rates because you had a comprehensive claim, unless they raise the comp rates on EVERYONE in your region. In all probability they will total the car out, as the fix (another engine) would cost more than the car is worth, less its salvage value.

If you had ANY water in the oil it would make the oil look milky on the dipstick.

Note: Never drive into deep water again.


Without knowing more about the depth of the water you drove through, it’s hard to say. I’m inclined to go with MG’s theory. However, modern cars are designed to make it VERY DIFFICULT to actually ingest water into the engine.

It’s not impossible, but it’s not easy.

I suggest you consider a faulty crankshaft position sensor, which could easily have been damaged by splashing water.

Having said all that, if you drove through DEEP water, such as a foot or more, then anything is possible, and MG’s theory may be correct.

NEVER, EVER, EVER, drive through deep water. It’s dangerous, it can destroy your car, and it can kill you.


What do you mean; you “checked the ignition”?

I think this car uses plug wires that fit into tubes and any water splashed up in that area can cause a misfire as water can get inside the tube no matter what. The same can be said if water gets up under a plug wire boot at the coil connections.
If the misfire is bad enough it can cause some strange or loud noises.

Some more info would help of course. Any Check Engine Light on? Is the car running rough at all speeds, at idle only, etc.?


Tell me this: does the knocking sound remind you of someone beating on the engine with a hammer, and it goes faster/slower with the engine RPM?

If so, then it sounds like a main bearing or rod bearing has given out, due to either water entering the engine and washing out the bearing(s), or from hydrolocking which could have bent a connecting rod.

It is not a cheap fix. Either a rebuild or another engine is what would be next.


checked the ignition meaning that i pulled the plugs, wires, anthing that could have gotten wet and made sure it was dry. check engine light was on but when i had it tested it only showed a faulty gas cap. Also yes it is mostly at idle and 10 to 15 miles an hour after that it almost even stops knocking


the water wasnt even that deep maybye 4" just above the ankle line of your foot the problem was it was about 100" feet long the onlyway for hundreds of people to get home and the fire dept. was ther to insure the saftey as they let the cars go through until it got to unsafe to drive across any more.


yes until you get going pretty good


So we’re talking about possibly 4" + 4" = 8". Then you or oncoming traffic splash through it creating a wake or bow wave of greater depth. It could have been well over a foot deep when you drove into the wave. Then the electric cooling fan picked up just a few ounces of water and sprayed it into the intake snorkel at the front of the engine. It doesn’t take much to bend a rod or rods.

My suggestion is to have a pro give it a listen. I can’t hear it from here. If it is damaged from driving into high water, check with youor insurance company for a possible payment. Do you have comprehensive coverage?

If you do need an engine, and have no insurance to help, check out for one at a salvage yard near you. They might even install it for you.


ok i’ll try that and get back to you on the results