Hi, I'm new to this forum. I have an 86 300 SDL. 603.xxx motor. I have a quite loud "tapping" or "banging" noise that seems to be coming from under the valve cover. It never goes away. I have done a motor flush and synthetic oil change. I have not replaced the vacuum pump, but mine does have the rivets on the front, so I think it has been replaced, and the noise does not seem to be coming from it. It really seems to be coming from "Mid-valve cover" area. I do have leaky exhaust, I have new pipes on order, which by the way have been extremely hard to find. We have cut off the fuel supply injector by injector and the sound still stays the same. I don't think it is a rod knock, but it really is quite loud. I've read other posts on here about bad lifters and tappets. Anyway, here is a quick video of my engine, I just want to get any thoughts, or opinions. Thanks

http://youtu.be/mfKKkOzlC7s

I'm more concerned about the squeak than the tick. Make sure your pulleys all turn on the same plane. The tensioner pulley might be skewed and so because either the belt tensioner arm bearing or tensioner pulley bearing is worn. Or both. The tick might just be the belt tensioner damper. With the engine running, wedge a flat screwdriver between the upper Heim end of the damper and the head. See if that quiets the tick.

Sixto
87 300D

just read this online. Have no idea if it actually works, but would be interested in opinions since I have the same problem (noisy lifters):

"I have found a way to fix the valve train noise on the 603 engine, with this
mod the engine runs incredibly smoother and I believe has also increased
fuel mileage.
what you do is remove the oil filter cover and on that cover is a tube with
two orings on it, inside this tube is a small regulator valve, near the top
of the tube is a small hole with the oil flowing from the small hole to the
oring end, you need to drill that hole out bigger to allow more oil flow to
the hydraulic lifters etc., I drilled it out to 5/32",make sure no metal
pieces get into the valve and clean it out with solvent and compressed air
blowing from the hole to the oring end.
the cost is nothing and you can do it next time you change the oil, you will
not believe how much smoother the engine will run"

__________________
1986 300 SDL, gray on black, #14 head, 180K miles
1982 300 CD, silver on palomino, 290K+ miles [sold]
1980 300 SD, white on palomino, 500K+ miles when retired [uncle's car - inspiration for the above]

Very interesting. Did he do anything else but drill that out at the time I wonder? The original passages might have gotten sludged up and him applying greater pressure and volume may have overcome it.

The passages had to be good when the car was new or the customer would have complained. Also greater clearances somewhere else might be demanding a greater oil flow to enable the lifters to be serviced properly. It does sound though that unless there is something else seriously impacted it might be a good ideal.

You can always grab another tube and cap assembly from a junkyard to restore what was if there is no improvement.

Did the engine look really clean under the valve cover I wonder. Basically though excess wear clearances somewhere probably are demanding more oil flow to the area Than it was getting.

The tensioner has been replaced. Belt runs smooth, no problems. It really is a loud tick/banging from about mid-valve cover. I have read that thing about drilling a larger hole, but I have not heard anyone else having given it a try. I just did a flush and put in synthetic oil. I'm going to wait until my exhaust pipes come in and get that whole noise thing fixed. Then I'll be able to hear better. I've also heard that I should give the synthetic some time to work. If it is still bad, then I'm going to replace the lifters.

Ive read a thread here that mentions upper valve cover noises have been caused by very old injectors ,the fuel is entering the combustion chamber not as a full mist,much like nailing.Youll also get valve noise when the lifter guides need replacement.

Let be guess, between #1 and #2 cylinders? Clack clack clack? Goes away under speed?

__________________
http://superturbodiesel.com/images/sig.04.10.jpg
1995 E420 Schwarz
1995 E300 Weiss
#1987 300D Sturmmachine
#1991 300D Nearly Perfect
#1994 E320 Cabriolet
#1995 E320 Touring
#1985 300D Sedan
OBK #42

It never goes away, it is clearly a metallic clicking/banging.

Let us know where its coming from. Between #1 and #2 is a common head gasket failure.

__________________
http://superturbodiesel.com/images/sig.04.10.jpg
1995 E420 Schwarz
1995 E300 Weiss
#1987 300D Sturmmachine
#1991 300D Nearly Perfect
#1994 E320 Cabriolet
#1995 E320 Touring
#1985 300D Sedan
OBK #42

But if you read the whole thread at:
http://www.carkb.com/Uwe/Forum.aspx/mercedes/5104/300sdl-valve-noise-cure
there is debate about this topic, and others point out that the hole in this tube does not supply valve train. It would become a dump back to sump.

They say the tube is more of an air entrapment relief, what with a check valve and tight double o-ring sealing at the bottom. Meant to keep the canister from draining after shutoff, presumably for quicker-to-pressure next start. It's not clear to me which way the air would be moving and under what kinds of conditions, from the oil canister to crank, or vise versa? etc..

So if anything, enlarging the hole would reduce overall pressure available to valve tappets. Leading me to think the noisy problem might be too much pressure, versus not enough. How could you have too much pressure? Clogged ducts or passages in other places maybe.

What about cleaning this engine with an oil flush, maybe a couple times, then refill with good diesel grade oil and see if it helps?

__________________
Cheers!
Scott McPhee

1987 300D

I did a flush. Put synthetic oil in. I'm going to replace the o-rings. My exhaust is loud, I have pipes on order. I'm going to wait until my new exhaust is in, it is hard to tell what noise is what with it being so loud. I've read that I should be patient and give the synthetic time to "clean". I'm really hoping I don't need to do a head gasket. I will post my findings as I go so that anyone else it the future can read what I found with mine.

FWIW, I just changed my IP delivery valve seals (both the rubber o-ring and the brass washer). Now it runs much quieter AFTER fully warming up.

I have freshly rebuilt injectors (thanks Sean!) and have been running synthetic oil for about 1000 miles.

I have tried cracking each injector line and there's no significant change in the noise.

If anyone has any more ideas, please let me know.

__________________
1986 300 SDL, gray on black, #14 head, 180K miles
1982 300 CD, silver on palomino, 290K+ miles [sold]
1980 300 SD, white on palomino, 500K+ miles when retired [uncle's car - inspiration for the above]

You can loosen the injector lines one at a time to see if you can isolate the noise to a cylinder. If so, the noise is probably coming from the injector rather than the lifter. [edit] Note to self, don't wait hours between writing and posting

Is there a dribble of oil near the #1 exhaust runner and chain tensioner? If so, it might be that the head gasket is coming apart and blocking the oil passages to the lifters. I know, not what you want to hear.

Sixto
87 300D