In need of engine assistance !!

My last post was about looking for an engine for my 1987 420 Sel.. Really what I need is a reply on who knows about these engines ?? Basically the engine runs like normal, good oil pressure & no sensor lights saying it needs help.. The only thing that is the problem is a tapping noise, very fast and repetitive.. When the car is in gear the noise diminishes, but when you rev it up the noise increases.. What is making this a nightmare is all the different opinions that I am getting from several mechanics and fellow co-workers.. I work for NAPA autoparts in stuart, Florida.. I have basically restored this 420 SEL, it was in almost mint condition before the engine took in water.. Here is what happened, maybe this will help in your reply.. After the hurricane hit south florida ( Hurricane Wilma ) , I tried to go to my house to access the damage.. While driving down a street, in about a foot of water, not to fast, but not to slow.. My car went into a sink hole ( the street ), and the car hit like 3 feet of water.. Water came over the hood & the car shut off.. I threw my shoes off immediately and jumped out of the car as quick as I could.. Pushed the car through the water, popped off the air filter cover, which was filled with water.. Soaked up the water in the air filter chamber, had a bystandard who was a mechanic help me with the car.. Got the car started and then I heard the noise.. Before hitting the water and taking water in this engine was in tip top shape.. Drove the car to a friends house, very slow.. Went and got my buddy to tell him what happened, and he noticed that water was pouring out of my exhaust system.. Litterally it was like a waterfall.. He advised for me to run the car for a few hours to let the water pour out totally or evaporate from the heat.. I did and the noise was still there.. Let it sit for the night and started it the next day.. Started immediately, no hesitation.. The tapping noise was still there, so I shut it off.. The engine is not smoking at all, no misfire, when you pop the hood and look at the engine it is not even shaking the slightest bit.. Seems like always, but now has a noise to it.. Not good at all for this Mercedes.. Sorry for the long description, but I need a benz engine master to help me out.. Maybe even tell me what the problem is..

Thankyou for your time...

I'm no " engine master" on your car but before I thought the worse I would look at maybe something more simple. The things that come to mind are maybe the timing chain and/or tensioner, or perhaps the lifters on your car [are hydraulic] and may not be pumping up after a loss of oil pressure? It could be something worse since you did introduce cold water into the intake of a hot engine. I guess the first thing I would do in your shoes is change the oil, and maybe run in a oil additive such as "Risoline" and see if that helps it out.

My last post was about looking for an engine for my 1987 420 Sel.. Thankyou for your time...

Have you checked out your distributor, plugs and wiring yet? I have a 1989 430SEL with 187,000 miles on it and have repaired it and maintained it all myself since 1991, but the last time I started getting the problem that you seem to have was in a 1992 Misubishi Diamanti LS back in 1994.

I cleaned my engine at a car wash, and yes I sealed off the distributor with plastic wrap and rubber bands, but water got into the spark plug wells, that are hidden under a cover, and shorted out two plug wires. A dealer "check" of the problem ($87.00) found that I needed new plug wires, at a replacement cost of another $165+.

I bought the OEM new wires for the Diamanti at a discount auto parts store for $83.00 and replaced them myself in about an hour. The Diamanti has ran fine for the last 11 years (67,340 miles) with no problems.

In the 420SEL, I've replaced the cap and rotor once for under $100.00, and it still runs just fine.