'90 300E base intermittent valve train tapping - new development - PeachParts Mercedes-Benz Forum

Andy_M · #1 02-07-2012, 06:41 PM

Have a '90 300E Base SOHC 6 3.0 engine. Engine has 200k on it and head was redone by a good shop at 150k. Engine has always tapped for 5 or 10 seconds when you start it cold, then quiets and that's it. Oil is changed religiously every 5k with Syntec 5W-40. It runs like a charm. Daily driver.

Two days ago it started tapping on and off when driving it. Taps the same whether driving or idling. Pressure gauge shows plenty of oil pressure. Oil level is full and oil condition is clean and fresh looking. Noise comes and goes. Sometimes it is persistent, sometimes lasts only a few secs. TONE of noise changes as well, sometimes is a solid sounding "clack" sometimes has more of a ringy tone to it. Always emanates from under the valve cover. Even though the pressure appears to be fine, a peek inside the filler cal lead me to believe that the valve train, while not dry, appears that it may be drier than it should be. Again, pressure indicator is showing 3 bars running and 2 at idle.

I am thinking that I have a lifter(or maybe 2 ?) collapsing But this is actually quite a sudden development. I am also wondering if I have a sudden oiling problem to the top of the engine.

Anyone ever experience this before with a 3.0 SOHC ? Any one have any input or ideas? All input is welcomed.

d.delano · #2 02-07-2012, 10:23 PM

Timing chain or tensioner would be my guess.

Andy_M · #3 02-08-2012, 09:47 AM

Other than the valve tap, the car runs and idles beautifully. Is not hurting for power, and is making no noise at the front, only on top and it is valve noise.

Can you elaborate a little bit on why you would suspect timing chain or timing chain guide?

Clemson88 · #4 02-08-2012, 11:42 AM

Quote:

Originally Posted by Andy_M

Other than the valve tap, the car runs and idles beautifully. Is not hurting for power, and is making no noise at the front, only on top and it is valve noise.

Can you elaborate a little bit on why you would suspect timing chain or timing chain guide?

Pull the cover and take a look. Does your engine have an oiler rail?

Andy_M · #5 02-08-2012, 02:55 PM

I will try and do that tonight. Engine is original and is a 103. I believe the serial is 189408.

Ferdman · #6 02-08-2012, 04:00 PM

Andy, I would suspect the timing chain tensioner also. It may not be holding hydraulic pressure which keeps the timing chain tight when the engine is running. You may want to have a local MB-trained indy to check out the current situation and prevent any inadvertent damage by allowing it to persist for an extended period.

duxthe1 · #7 02-08-2012, 10:02 PM

#1 bad lifter
#2 cam tower loose

Pull cover and inspect.

Tensioners don't give trouble in the 103.

d.delano · #8 02-10-2012, 07:31 PM

Quote:

Originally Posted by duxthe1

Tensioners don't give trouble in the 103.

Are you absolutely 100% sure about that?

Tapping upon startup is pretty common with the M103 due to one or more collapsed lifters. If it goes away once the oil pressure comes up, it can be lived with. Mine does it every other startup, it goes away, and I live with it. I have cleaned out the oil tube and it still taps, so the only way you will get it to be quiet is to replace the noisy lifters. I have been driving it like that for around 40k or three years. It's not a nuclear emergency to replace the lifters.

If it taps while driving, for example when the oil pressure is up where it is supposed to be when driving down the road, it's a more serious problem than just lifters. I think the tapping noise is the timing chain slapping against the guide because the hydraulic tensioner isn't doing its job.

It's unwise to assume that 'tensioners don't give trouble in the 103' because I know they have, and the chance of that is greater after the head has been reinstalled (if somehow the original tensioner was reused or the new one was not installed correctly, which is possible). One should never say never with these old cars! Do not assume, rule it out before the chain jumps a tooth while you're on a long trip and ruins the engine. It's better to know for sure than to assume.

The M103 is a hardy lump but just as susceptible to the unforeseen as anything else.

Andy_M · #9 02-13-2012, 01:14 PM

OK...yes, there is an oiling tube or rail that runs down the center. I will check this for any signs of being plugged and clean it thoroughly.

As to the timing chain discussion...I'm not dismissing the idea for no good reason. I refurbished the head at 150k miles (50k miles ago). I replaced the hydraulic chain tensioner at that time. I did not, however, replace the lifters (I know...I know..) Yes, I am sure I installed the new tensioner correctly. The noise is not emanating from the front area of the head. It is clearly on top, toward the back of the valve cover.

This issue is also VERY recent and very sudden. It started and quieted down as it always does. The car was then driven 3/4 mile away to a friends house and shut off. When it was restarted, the tapping did not stop as it normally does. My wife shut off the car, waited a while and checked the oil level, saw that was fine, and brought the car straight back home and parked it. The car was only driven about 3/4 of a mile with the tapping constant, and it was not bone dry, so I am sure no serious cam or rocker arm damage had a chance to occur.

I do believe it is a either a lifter or a lose cam tower, as the tapping is coming from the same location that it always did on cold start up, just now it isn't going away. I have ordered two lifters from the local NAPA and should have them tomorrow. Tomorrow night I will pull the car in the garage and remove the cover to see what I've got.

I will report back after

duxthe1 · #10 02-13-2012, 01:47 PM

Quote:

Originally Posted by d.delano

Are you absolutely 100% sure about that?

Yes, I am sure. The 103 camshaft always has valves opening and closing and doesn't experience the slapping back and forth caused by the valvespring pushing the cam forward during valve closing faster than the chain pulls it. That is very common on cams 4 cyls in length but not 6cyls in length. Given that the tensioner is a ratcheting device, it doesn't get slack without oil pressure. You have to screw up installing it for it to cause problems and it will be immediate.

sptt · #11 02-14-2012, 01:52 AM

I had the same issue and finally found that a bolt (or screw) that held the oil rail in place had come loose and was causing the tapping. At first it would go away with new or more oil then it wouldn't stop. I spent HOURS trying to figure it out! It was the one towards the firewall. Re tightened and haven't had an issue since. I was like, "go fricken' figure!"

Andy_M · #12 02-16-2012, 07:10 AM

Well, we got the lifters in and pulled the cover last night. It was apparent right away that there is no oiling problem--LOTS of oil and pressure both. Oil rail (tube if you like) is pristine clean and was tight. All rocker arm carriers are tight. All lifters are pumping up....and at about the same rate. There is no apparent slop in the rocker clearances. We didn't put a feeler gage on them, but it is pretty obvious that there is nothing loose or sloppy. The top end is clean as a newborn. No sludge or crap anywhere, just clean and pristine mechanicals and oil. You'd think the engine had 30k, not 200k on it.

Four key things we observed: 1) the tapping does not occur when the car is started after sitting and gets fully cold. We had to wait for it to warm up before the tapping started. 2) Once it starts it moves around...one will tap, then stop, then another taps, then stops, then a different one, etc. Never two at a time, and never on the lower end of the head, only the valves along the top (closest to the air filter) of the head. 3) The last time we changed the oil (maybe 5 weeks ago) we used Valvoline synthetic because it was on sale, however I can't recall the weight they had. I have always used Castrol Syntec 10w-40 in this motor. This oil appears quite thin or watery.

I bought 6 quarts of Castrol Syntec 10w-40 and a filter. I really have a hard time believing that 4 or 5 lifters suddenly all took a crap at once. There is no evidence of poor oiling ANYWHERE, and everything is tight. There is tons of oil flow, and the pressure is good. The mechanicals are clean as hell and so is the oil. We are kind of baffled, but are now thinking it may be an oil problem, either the wrong weight or just doesn't like the Valvoline. My Porsche has a similar issue if I use certain oils in it - the lifters drain when it sits and it taps. Put the same exact weight Mobil 1 or Royal Purple in it and it stops doing that immediately.

I'll let you know how I make out......

S124300 · #13 02-16-2012, 10:53 AM

Our 200k miles m103 124 estate had a similar cold tapping, especially after sitting and was much worse in the cold weather with occasional odd tapping on the move until it warmed up.
It was the timing chain tensioner, as advised by an independent Mercedes workshop. The tensioner had worn a little on one side and that was enough to cause it to lose oil pressure apparently. A short term fix was to take the piston out and turn it 180 degrees. Refitting it only as far as one click into the sleeve before putting the spring and bolt cap back on. It has been much quieter since, even on Mobil 0W40.

ps2cho · #14 02-16-2012, 11:23 AM

Put some Rotella-T 15-40 diesel oil in her and see if that helps. There is no reason for you to run Synthetic in stock M103, especially at 200k miles, the ZDDP additive package in diesel oils are greatly appreciated by the cam + rockers.

Make sure the noise is not from the belt tensioner shock. Its right next to the engine and the bushing wears which allows forward/backway play and it will make noises that sound like its coming from the engine. Grab it and if it moves back and forth, either replace the shock or put two washers on either end and retighten so it does not move anymore.

Adler · #15 02-17-2012, 12:04 AM

[QUOTE=ps2cho;2885710]Put some Rotella-T 15-40 diesel oil in her and see if that helps. There is no reason for you to run Synthetic in stock M103, especially at 200k miles, the ZDDP additive package in diesel oils are greatly appreciated by the cam + rockers.

ZDDP additive oil: So very few of us use these oils , required more so on the earlier engines . My 103 engine stopped its morning ticking after a switch over to Delo diesel oil