MetaL63

As luck would have it (which apparently I am without) we have been visited by the 6.3 engine tap gremlin again.

First run in with this pest was in my 2007 ML63 w/48k miles. I bought the vehicle CPO and good thing I did as it was in the shop the whole time I owned it. After 2 months of in and out with parking brake issues, intake gasket/bolt issues, cracked vacuume line issue and electric window issues I though we had finally got it all taken care when I went to pick it up for the last time. As soon as it fired up a loud ticking sound immediatly caught my attention. Mind you the vehicle had just been test drove so it was at operating temp. When popped the hood while still parked in the service, it was apparent something was definately wrong as increasing the engine RPM just made it louder. Thats where it stayed as I traded it in the next day with the dealer giving me almost what I bought it for in trade.

This weekend just to say was a bad flashback as my wifes 2011 C63 P31 decided to make the same noise. In this case the engine has barely 13K miles on it and was the first start after sitting for about a week. There are only about 1500 miles since its last service but I decided to check the oil anyways as about 2000 miles into the service before I had to add approx 2qt of oil when the add oil light came on. To my suprise the oil was low so I ended up adding another 2qts to bring the level right under last red bump on the dipstick. Fired it up again and let idle for a while and the noise was still there. Drove the vehicle up and down the street for a few and the noise is now gone. What boggles me is the last time the car was low on oil it did not make any noise which would lead me to believe the low oil level was not the cause of the issue. We have owned it for about 1.5yrs and has been flawless until this point. Now the wife is on edge weather to just write it off as a fluke or to get rid of it before something does happen and are stuck with a highly depreciated vehicle due to service history.

ZephyrAMG

I had engine tap after not driving my car for a week or so. Drove it and it was gone. Oil was at the right level...

USCGTO

So after reading this thread and others with similar noise issues, I have a question.

When I drive back into the garage after lets say a 30-40 mins of commute back home - spread over 20 miles, sometimes there's a tip - tip - tip noise for a few minutes.. Is this what we're referring to as as ticking noise?

Trying to wrap my head around if I need to visit the dealer or not?

ZephyrAMG

When you start the car, cold, usually after sitting for 2-3 days, you will hear a TAP TAP TAP TAP...or TICK TICK TICK front, mostly left side until you drive it out. It will disappear when car warms up. It literally sounds like you are slapping three fingers into the palm of your hand. Not a clap but more of a tap...

PetroC63

The ticking noise is normal and so is lifter noise after the car sits for a long period of time.

Garrett@Oscaro

Quiet ticking noises when engines are cold is almost always caused by cold oil being too thick to properly lubricate the lifters. When the engine warms up, the oil becomes thinner, better lubricating the lifters and eliminating the noise.

When there is a quiet tick after the engine is warm, it almost always is coming from the fuel injectors. This is completely normal.

Both issues can be identified by using a Mechanic's Stethoscope.

On the other hand, much louder Tap's and Ticks could be indicators of a leaking exhaust system, or bigger engine troubles. If you can hear them in the car while driving, I would investigate deeper into the issue.

Now this is an issue to be concerned about. Its not normal for a car to be 4 quarts low on oil 1500 miles after it's last service. Are there any indicators of an oil leak?

khmergod

The light tapping sound is normal. Just about everyone with a c63 will tell you that. I only drive my car once a week and when I start her up she makes a light ticking noise for a couple minutes and disappears.

Merc63

It's just a stuck lifter. Mine did it the other day after sitting for a month. Let it idle up to temp and it will go away.

Read about hydraulic lifters.

Merc63

I thought 5w40 oil is thinner at start up and thicker at operating temp, hence the 5w and 40 viscosity...?

I think allowing the lifters to heat up, allows them to expand slightly and get the oil flowing. Or driving it and increasing oil pressure should help.

Jon2007E63P30

Just to add a datapoint to this issue.

2 oil changes ago I believe I had a poorly seated oil filter. 70% of the time I turned on the car I got the loud cam adjuster noise. After replacing the oil and filter the noise disappeared completely.

It is really the drain valve which was not properly seated, so the filter would drain in a couple hours. Oil analysis showed no change so I guess I am ok for now. Of course mine is a daily driver.

Garrett@Oscaro

You are correct that there are viscosity modifiers added to your oil so that the oil is thicker when hot, and thinner when cold, when compared to a single grade oil.

With that said, most oils viscosity per ASTM D 445, such as a 5w40 oil, is about 6x thicker at 40°C than at 100°C.

Here is a video I found on the subject, which shows oil vs. heat of a 5w40 oil:

MetaL63

Just to clarify it was 2qts low at 2000 miles the first time then about the same 1500 miles after its last service but even that seems excessive oil consumption. I am aware the pcv system injests alot of oil on these engines but wouldn't think it is that excessive. As for oil leaks, this car is flawless and has never leaked a drop awywhere I could see.

MetaL63

Im used to the whining and creaking the motor does. Thing is I never heard the tapping on this car till this weekend and it was just like my ML. Almost sounded like a loose rocker on a pushrod motor. Definitely coming from the top end. Guess we can chill for now and wait for it to happen again.

bhamg

Correct me if I'm wrong but that loud lifter clatter after the car has not been run for a while...that is a high-wear situation, no?

bhamg

My car consumed oil like crazy for 20k miles, then seemed to stop almost entirely in the next 2k miles. Now it's one quart every 7k miles. These treated, linerless blocks seem to take a long time before oil consumption stabilizes. This is one (perhaps most important) reason IMO MB moved to the ultra-low ZDDP 229.51 oil recommendation. That amount of oil blowing through the cats is a cat-killer.

Merc63

It's only going to last a few mins. There is still oil between the surfaces and it should be only clicking at idle, low rpms as its allowed to warm up.

All youre hearing is the gap between the cam and tappet.