M103 valvetrain noise
 

When accelerating the engine when it is cold I get a faint valvetrain noise that persists for a few minutes until the engine is warmed up a bit (though not at normal operating temperature). Are M103s like this normally? The car is quiet at idle when cold, it is only until the car is under acceleration that I can hear the noise. I'm using Rotella 15W-40 and something is telling me that this might be a bit too thick.

Anyone?

So is at temperature or at load or both? I would say the oiling tubes for the valves maybe an issue without a bunch of further info. I havent dealt with this much myself but might do a search to see what others have.

Not normal for a properly operating M103, and 15W-40 is, under normal circumstances, not too thick in many climates. My M103 has used 20W-50 or 15W-50 its entire 22-year life, with no valvletrain noise or other adverse consequences.

mbzman, it's possible that the timing chain tensioner needs to be replaced. Our 1992 300CE (with the 104 engine) had a valve train noise that concerned me. An experienced tech at our local MB dealer traced the noise to the tensioner. A new tensioner resolved the issue.

Factory fill for that vintage engine was 15W40 mineral oil. I run Mobil 1 15W50 in our 124 cars year round without any issues.

The car has only 70,000 miles and the timing chain was replaced when the head gasket was replaced last year. I will look through my records but I would assume that the tensioner would have been inspected when they did the chain? Again it is a very faint noise and is only heard during acceleration for the first few minutes after startup. How hard or expensive is it to change the tensioner?

I've got some excessive valvetrain noise from my M103 as well but I'm suspecting that a previous owner abused the car a bit (though its really clean in and out), I am paying close attention to this thread....timing chain check is in store for my car.

70,000 miles is very young for a M103 chains(should easily go 2 or 3X that). It's tossing money away. But, they should have done a valve job and replaced the guides as they are soft on early M103's and wear out quickly.
I think it would be wise to investigate. For me, I'd look at buying only a factory tensioer. Maybe they messed up the old one when they re-set it somehow. Don't know how..

The valve job was done when the head gasket was replaced. The valve guides and seals were all replaced. Again the noise goes away once the car get to around the halfway mark to operating temperature and does not return at all. Even when I do hear it the noise is very faint and can not be heard over the radio at medium volume or the blower going. Is it possible that there is one or more lifters that isn't building sufficient oil pressure until a bit of driving? I do get a bit of faint lifter chatter on the odd occasion but it goes away after 1 second.

Do you hear it with the window open? Mine is virtually unnoticeable at idle and inside the car, but step on the gas next to a fence or some bushes (for acoustic reflection) you can hear it pretty well.

I will have to try and listen a bit closer. My noise seems to go away after it warms up a bit so I only have a small window to be able to listen.

Have this car seen frequent oil changes? You are using the right oil, but you need to change it often enough to prevent any sludging which would be the likely cause of your problem.

In EXTREME cold, like 10 degrees F or colder, you will get a slight amount of valve noise for a few seconds after start up. Hearing such noise in warm weather is alarming.

If it were mine, I would get it to operating temperature, which usually requires about 17 to 20 miles of driving and put a drain pan under it as soon as it is shut off and drain the oil overnight. With the oil you are using this will get the most sludge out of the engine that is possible. Continue to do this about every 500 to 1,000 miles for a few cycles and see if it goes away. If it does, go to a reasonable oil change interval and always drain it while the engine is at operating temperature.

Draining oil from a cold engine leaves the sludgiest stuff clinging everywhere. Draining it hot gets the crud out much better since it is churned up in the oil.

Oil is always changed about every 3000 miles several times a year and is always hot when I drain it. Since the car is mostly run in and around the city I usually try to get it up to operating temperature all of the time. The oil remains quite clean between intervals which I think is a good sign for the cleanliness inside the engine. The car has always received oil changes on time and it was dealer serviced for most of its life.

As suggested earlier do a hot oil change and a switch to Delo 15-40.
my 103 became quiet after the change.
mak

Have you thought of an exhaust manifold leak; it has all the symptoms.
The vast majority of small manifold leaks pop when cold under acceleration, then seal up when hot.
Maybe leaking around the EGR system, if your car has one, or the manifold is cracked.
If the tick only occurs during acceleration, and not when just revving in neutral, it seems unlikely to be a valvetrain issue to me. The valvetrain and the oil supply don't know whether you are accelerating wide open or in neutral.

But..... covering all the bases; the hydraulic actuators (valve lifters) can be replaced relatively easily and inexpensively. They are in the ends of the rocker arms, so teardown is very minimal.

DG