Help! My 300CE (m103) driven through deep water, now clacks
 

Dear daughter drove the car through some rainwater, probably 6-8 inches deep, and now the engine is clacking loudly but seems to run smoothly. Any ideas what happened here?

Where is the noise coming from?

It's definitely an engine noise, coming from the valves somewhere. It's a pretty loud tapping and increases with engine speed. Other than that I don't know. I'm changing the plugs first thing in the morning, simply because I have a set handy. There's an Mercedes independent shop just down the street, and I'm taking it there for diagnosis. I will post additional information tomorrow. Right now, I can't sleep.

My S420 periodically has a clack like that. I did some very close listening and it turned out to be a cat-converter that was rattling. It might be worth a second look/listen.

The water could have loosened some carbon deposits on the piston tops. We used to spray a fine mist of water in older hi compression cars to remove carbon. If pieces remaining the engine would clack.

First, I believe you when you say it's coming from the motor itself, but are you absolutely sure of that? Could it be coming from a pulley up front? Water in a pulley bearing could have toasted it - The smog pump comes to mind.

Personally, I think that 6-8 inches of water is far too little to actually get some in your motor. For the water to get sucked in, it would have to go through the air intake hose, past the air filter, etc. It would take more than a little splash to get enough water in there to get past the air filter and if you had, the motor would have stopped on the spot.

Could there be mud on the serpentine belt?

How's your oil pressure?

I'd be more inclined to believe that the noise is coming from a belt-driven accessory, but you should get a mechanic's stethoscope and check it out to be sure.

I believe that if my 2nd daughter told me she drove in 6-8 inches of water, it would mean 16-18", ... or more. That's why she's in a (disposable) E320.

Check the oil for a brown muck like peanut butter, check under the oil fill cap, will indicate water in the oil.

If so then the wheel bearings, transmission fluid, and differential fluid should also be checked/serviced.

Good advice.

Still, if you managed to get water into the block and in the engine oil, you'll also be looking for how it got in there, since I can't think of a way without really submerging the motor.

If you DO have water in your oil, you will want to drain it and flush the motor ASAP as rust will very quickly start ruining your motor.

I've blasted through a good 15"+ inches of water at 30mph before (on accident) in my 300SD, and had no issues aside from the surprise...and thrill, of seeing 10 thousand gallons of water go spraying in the air from the fender wells! :eek: :D I lost power steering for about 20 seconds due to wet belts....but it came back quickly. :D I've also had to ford water about 1.5-2 feet deep before to get past a road.....no issues then either....I did loose electrical power+steering for about 1-2 minutes....but no other issues. Probably would not try that in a gasser.

I would bet on water having gotten into a bearing on the front of the motor....or the alternator....as has been mentioned, the way the MB air intake is designed, you'd need to go through water deeper than the front bumper in order to suck anything in....

Dive! Dive! Dive!
 

Sounds like darling daughter may have driven the automobile thru too much water too quickly. What you describe is most likely the sound of a connecting rod wacking the block at the bottom of the cylinder bore. Normally the rods have clearance. One of them was probably bent while trying to ram the piston thru the rainwater in the combustion chamber. Sorry.
Don

On fifth gear in Britain they purposely drowned a W124 gasser while running and it survived.....all they did was pull the spark plugs, crank it a bit to blast the water out, put them back, cranked, and it fired up and ran fine! :eek: I suppose that was probably luck though.

Wouldn't the water have had to exceed the front bumper height to even force any into the air cleaner or engine? That'd be like 2 feet+ of water! :dizzy2:

I'm more concerned about it getting into the oil through breathers or sitting partially submerged until a friend secretly tows it out, ... and having oil in the oil-pan.

Any water that submerges the front hubs, or the top (breather) of the transmission and differential, is especially bad IMO. There's a reason my Land Rover has breather tubes up high in the body.

dpkreuze: If you're correct, and you may well be, would you pay to have it repaired? My mechanic, who has 8 years of familiarity with this car, says it sounds like a problem "down" in the engine, and he would not recommend repair. I'm going to get another indie to look at it, and if his opinion is the same, "cash for clunkers" may get this one, and I hate it. The car has a totally rust free body, diamond blue with gray leather, and I could have been happy with this for years to come.

Sorry to hear about your car troubles. I also have a couple of daughters that have made car maintenance challenging for me at times. It sounds bad, but I’m in Tinypanzer’s camp on this one. I think it would have to have been really drastically submerged to get that much water into the engine to cause troubles internally.

Babymog asked this question, and I haven’t seen the answer:
“Check the oil for a brown muck like peanut butter, check under the oil fill cap, will indicate water in the oil.” I’d also look at the dipstick. Did you check the air cleaner to see if it was wet with water or showed signs of flooding? If there’s enough water in the oil to cause this type of immediate damage, I would think it would be clearly evident, IMHO.

Hmmm
 

As I am a mechanic I wouldn't pay someone else to repair the engine. I'd repair it myself. My opinion is that cost of the replacement of a connecting rod may well exceed the value of an old car. I just "clunkered" Mom's winter beater 91 300E 4matic. I consider the program a waste of a lot of perfectly good hardware. It sure did PO my "progressive" friends when they found out this right wing wacko cashed in on our fellow tax payers, however.:smartass: