Hydro-lock?

my son drove his lancer thru some high water and the engine shut down yesterday. Today, I went to try and start and the motor was making a knocking noise. I quickly shut it down, opened the hood and found out the oil dip stick had a light greenish color to it. Is the car cooked beyond repair??

The fact that it started at all gives you some hope of recovery. Still, it may well cost more to fix it than it would to just replace the car.

It’s hard to say. Since the engine started today there’s hope.

Change the oil and air filter, clean and dry the ignition system (change the plugs and wires, and if it’s distributor based, change the cap and rotor), and see how it sounds. Post back with the results.

removed all 4 spark plugs, all are dry. Looking through the spark plug opening, 1st cylinder has a wetness. All the others look dry. The oil dipstick has a light green-yellowish color. Going to drain the oil and see what comes out. Can you further advise where else to proceed?

Automatic or manual transmission? Either way, you should change the transmission fluid or oil. I wouldn’t drive over a mile before doing that. However, I would wait to see if the engine is going to be okay before spending money on the transmission.

The forces involved with the engine attempting to compress an incompressible fluid like water can bend a connecting rod. This results in the bottom of the piston skirt striking the crankshaft counterweight at bottom dead center and causes the engine to make a knocking noise while running.

dried out all that looked wet. changed the oil, replaced all spark plugs. Engine started up, no problem. Motor idles smoothly but, has knocking noise. Can you advise for next step?

It sounds like a rod was bent. The engine will likely self destruct soon, probably when you rev it up getting out on the highway.
You could -

  1. Rebuild the engine.
  2. Replace the engine.
  3. Replace the car.

Is it insured fully. If yes it can be covered likely.

Air compresses but water does not. You likely bent a rod and the engine needs internal work.

How old or new is this boat?

Lancer is a 2008 model. will have my son check with his insurance for coverage.

Getting significant amounts of water into a modern engine isn’t the easiest thing to do although I’m sure it can be done. You’ve changed the oil. Any water in the oil (you’ll see it. Oil and water really don’t mix)? How about the air filter? If it is dry and there isn’t any water in its containment, just maybe water never reached the inside of the engine.

If there is no drivetrain damage, what else could be wrong? Well, there could easily be one or two cylinders not firing. Maybe the timing belt – which probably was not designed for submerged operation – has slipped a tooth? Maybe the crankshaft position sensor is damaged? Frankly, I’ve no real idea how to approach this other than to test possibilities one by one or to tear the engine down, examine everything, rebuild it, and pray. Hopefully someone has a better idea.