Please Help!

I have a 97 E420 and the vehicle is in good condition.
Recently, my wife went to full service gas station and the attendant put in regular unleaded gas. She ran for a while and then the tapping noises started from the top of the engine (louder on the drive side). I investigated further and found the noise came from the over-head valves.

I quickly refuel premium gas and the noise become lesser. Also, I added the valve lubricant to the engine and it seemed to help. A few weeks later, I changed oil (synthetic 5-50 oil)and the noise reduced significantly. The engine sounded normal. I drove it for about 2000 Km and the noise came back. But the noise is present intermittently. Usually, the noise becomes louder when the vehicle is stopping or idling for little while. If it is cruising a few minutes then the noise suddenly disappears and the engine sounds normal again. The vehicle is running smoothlyand still has good power during acceleration.

The questions are:

1/.Is it true that my engine is losing pressure when this problem occurs?
2/.What could be the cause for this tapping noise problem? I heard from some peope that this is a common problem for this V-8 engine.
3/.What is the best approach to repair this problem without incurring huge costs? As you know the dealer wants $$$ and sometimes they don't fix it right.

Thanks in advance... Greatly appreciated for any comment and/or solutions!

 

what is your oil pressure when the noise is present?

 

Hi Alex,

Smart idea...

I have not checked it.

What should it be?
How do I check it?
Do you have the procedures?

Thanks in advance for your assistance. Greatly appreciated!

 

Is it true that my engine is losing pressure when this problem occurs?
Quite possibly but this may not be a major issue. Just annoying.

You state you are using 5-50 oil. This is thicker than recommended by MB.
MB specify (but please confirm since you are I assume in USA) 0-40.

Stuart

 

benz does specify Mobil1 0-40 full synthetic. works well, but you can get around it on most of the older engines. still use 0-40 where you can though.

as far as pressure, your car (W210) should have an oil pressure indicator in the instrument panel. the pressure should not drop below the "1" at idle, and should snap up towards the "3" with an rpm increase. as far as an actual spec, and how to check it on your engine (M119) i dont know it off the top of my head, but if you give me a couple of days i can probably find it for you.

 

Thanks for all the help so far!!! VERY APPRECIATED.

I will try to replace the oil again with 10-40 synthetic. But any advise on the process to check the oil pressure and the steps to replace the noisy valves from the Mercedez repair manual.

Thanks again !

 

10-40 or 0w-40?

Stuart

 

if you car is a 420 V8 with a 119 motor you probably have an issue with the oil crossover tubes under the valve covers. they are little black plastic tubes on your rocker arms that lube the cams. they have little caps on these tubes that fall out and then poorly lubricate the cams. this is a good possibility that that is your problem. i think there are like 4 or 5 tubes per side.

 

Chassis 221,

Thank you!

Yes, my car is the 420 V8 with 119 motor. Your suggestion is quite correct about the lack of lubrication when caps are falling off. This may explain why the tapping noise come and go randomly. Lately, the tapping noise seems to go way.

Is it hard to repair the caps?
Is it a big job?
Do you have part diagram for these tubes and caps?

Please kindly advise.

 

you have to remove the caps that hold down the cam shafts remove them, the plastic tubes are held down by the cam caps that hold down the cams. black plastic tubes like 1-1.5 inch long. pretty easy job just becreful not to have the cam pop up or have the chain jump. should be no problem. if you look at the little black tubes on tghe end of them you will probably see that the little cap fell out its round. i will try to get you a pic.