Slight Engine Tapping/Rattling 98 C230 HELP!
 

Just about tried everything to get the tapping rattling to stop on my C230. This only happens when the car warms up after driving. It is perfect and quiet when you just start it. Used cleaning solvents in the gas tank. used cleaning solvents in the engine. Oil full with Mobil 1 15-40 Synthetic. Does not really increase in noise when I rev up the engine only when I let it idle you can hear it. Used stethoscope to listen and it and cant seem to locate where its coming from. Seems like injector side middle of engine but not 100% sure.. I just don't know if its ok to keep driving. Am I hurting anything by driving it like this. My next step is to maybe do the timing chain tensioner as Ive heard that can cause a noise like this. The tapping/rattleing is very faint and random. So it won't just go tap..tap.. sometimes its 1 second sometimes its 2 seconds apart. Very random. PLEASE HELP before I starting sinking more money into this beauty.

It doesn't sound like it's a big deal if it's truly that random and faint. If the tensioner is cheap enough for you to justify it's replacement that may be a good place to start. If not, drive it normally until it becomes more consistent

W124300E, it seems to me for that vintage engine the proper oil would be Mobil 1 0W40. Check your Owner's Manual. A lower viscosity oil may resolve the problem of ticking hydraulic valve lifters. Experienced the same phenomenon in our 1998 E320.

Better
 

I changed the oil to 0 40 and it didn't make much difference with the clicking tapping. Just a few hours I changed the timing chain tensioner and the noise is gone by 80% or so but still there slightly. Does that make any sense at all? Why would it still be there a little bit?

Is there any way to compare to another vehicle?

I made the mistake of not paying attention to mine.Before I knew aluminum was all thru the engine.I suspect oil pump chain.

W124300E, it may take some time before the hydraulic lifters quiet down completely, or perhaps that won't happen. The current sound may be the new normal for your engine. A MB-trained tech should be able to determine if the sound you're hearing is normal for your engine.

Hey guys. Just wanted to post an update and see what everyone thinks. The tapping seems like it got worse. Especially after long drives. The engine is just perfect when you start it drive under 30mph. But after I come off the highway the rattle tapping sounds is just louder. IM nervous its the timing chain. Gets looser as the engine gets hotter. Or do lifters do this sort of thing. IS there really nobody else here that ever had a problem like this? seems like its coming from the front. Any other suggestions would be wonderful. really don't want to take it to the stealership. They will rob me like there is no tomorrow. Thank you.

Look at the damping shock on the belt tensioner.

I installed a new belt tensioner and shock thinking that was the problem a few months back. Nothing changed:(.

Have you compared this noise to another similar model? The M111 isn't exactly what I'd call a quiet engine.

I have and they are bit noisy. But, this noise sounds like a marble inside the engine. But, only when it gets hot. Thats whats messed up about it. Why heat makes this noise pop out more. Ive seen videos of guides making this sort of noise, but how could it be perfectly quiet when its cool or when I drive under 30. Maybe I have gremlin inside the engine lol. Ive asked so many times and it seems like nobody else has this similar issue on this planet.

A little side note, Noise does change when I put it in neutral, becomes louder, but in drive it quiets down a little but still there.

W124300E, it's time to take your 1998 C230 to either an indie or a MB dealer to have the sound diagnosed professionally. Best to find out the root cause of the sound before the engine self-destructs.

Cam adjusters are known to get noisy with age. it's most noticeable at cold start. I'd also check the oil pressure since it gets louder when hot.....