Hello Fellow Mercedes frinds,

A week ago my engine started to have a tapping noise. It is not very loud but its quite irritating. The frequency is tha same as the firing of one cylinder why I assumed it was a valve or a conrod bearing.

I added oil because it was slightly low but this did nothing to the noise which is normally the case if it were a valve slapping noise. I used my stethoscope and it is clear that the noise is coming from the front of the right hand cylinder bank. I changed the spark plugs and all the plugs on the right side was white while the plugs on the left side was black.

After that I opened the oil fill hole and listened (on the right rocker cover) but there was no increase in the tapping noise.

After that i started to pull the spark plug wires to see if that did anything because if it was a conrod bearing i assumed that the noise would go away or be reduced if there were no combustion in that cylinder. No change to the noise at all.

I´m now a bit confused and need Your help. What can give a noise like this if it´s not the valves or the conrod? Why is the right bank running leaner than the left? Can the timing chain give a noise like that?

And most of all what can I do about these problems.

The idle is also a bit rough but have been so since a bought this car a couple of months ago. Its a Euro spec car so there are no catalytic converter.

Please help and many thanks in advance.

Mikael Westerberg
1984 500 SEL
Vanersborg, Sweden

Before reverting to more drastic remedies suggest you run a engine flush through before changing the engine oil and filter.

There is some clearance in one of the rocker assemblies. It could be a failing hydraulic element in a ball stud or a worn rocker arm. Do a search - there are a lot of recent posts on this.

Almost certainly not related to your mixture problem

__________________
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe

Chuck, what do you think about the oiler tube upgrades that those with the 5.0 liter M119 engine have done in the 500E?

500E still Racka Racka's on cold start up????

__________________
Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".

I think I'll read the manual and see if any of that is applicable to the 116 and 117 engines.

Good thought!

__________________
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe

You Guys are great,

A rocker arm would definitely explain the noise that I´m having. I will open it up this weekend to have a looksee. I´m not sure though if I understand how a faulty hydraulic compensator would explain this noise. The noise is always there except when the car is really cold (like around 0 F or -15 C) at startup. After some 10 - 20 seconds and all through warm-up and at warm conditions and independet of Rpm i have the tapping noise.

But I`m curious How to diagnose a bad hydraulic compensator?

Do You also have any ideas on what could be causing the right cylinder bank to be running lean and the left to be rich?

Please give me more feedback, I really really appreciate it.

Once again You guys are great.

Mikael Westerberg
1984 500 SEL
Vanersborg, Sweden

I’m am a first time visitor to this site and what I have seen so far is great, wish I’d found it a long time ago.
I am by no means an expert mechanic but would like to relay my recent experiences with tappet noises and the hydraulic clearance units. I have had my 83 500SE for about one year and have had a similar noise when the engine is worm, I have always assumed it to be a tired hydraulic unit and recently spent some time investigating the problem. Like you I used a stethoscope to locate the offending source of the noise, next step was to make a relatively simple special tool to compress the valve spring so that the rocker arm can be removed and then remove the hydraulic unit. I inspected the ware surfaces of the components and disassembled the hydraulic unit including the non return valve at the base of the piston, I then re-assembled the unit filling it with oil before installing the piston. This exorcise was performed on three valve sets ( one either side of the suspect source of the tapping noise ) results were as follows.
1. I used a clamp arrangement to bleed down the hydraulic units to facilitate re-assembly and found that the suspect unit took approximately half the force to compress ( oil was being displaced at a higher rate than the other units ).
2. I inspected the seating surface for the non return valve and could see a small amount of pitting ( if the non return valve passes the unit would require less force to bleed it down.
3. On close inspection of the rocker arm ware was evident on the camshaft contact face.

In conclusion, I will be replacing the rocker arm and the hydraulic unit for new items ( yet to be fitted ) I hope this is of interest and if you guys think I am barking up the wrong tree please let me know as new Merc parts here in Perth Australia are expensive.
I also have a request for information – What is the ignition timing settings for engine type 117963, it a Hong Kong import and I believe Euro spec car, vacuum advance only ( no vac retard ) have been told locally that it should be 16 BTDC plus or minus 3 with vacuum advance connected.

Good luck with the tapping noise

BobH

I have a 85 380 SE that had a pronounced tapping noise coming from the right hand side at first I thought it was my lifters I put in engine oil supplements hoping the noise would go away I removed the valve cover ,I had 1 cam lobe worn right down I ended up replacing it along with new rockers and oiler tube the job wasn't as difficult as I thought .

Sweden -

When the engine is cold the oil is thicker and the pressure is higher, thus keeping the weak HLC pumped up. As the engine warms, the oil thins and loses pressure and the HLC collapses enough to allow a tick.

The best diagnosis I know of is the Herr Fuchs finger check, which you will find if you do a search. The standard, though, is to replace the entire side since you probably have other HLC's ready to start ticking.

I am clueless as to the rich mix on one side. The only thing I can think of is that the idle air tube on that side is blocked allowing a rich mix.

Australia -

On the timing, the CD says 12-19 with vacuum so your local source is correct.

BTW - There is a great source for MB knowledge and parts in Australia. Name is Davide Frada, and his email is mb300sel@ozemail.com.au. I bought a set of Euro cams from him late last year.

__________________
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe

I had exactly the same problem and the same camshaft wear but the engine also had to have a complete rebuild at the same time.

Hello again friends,

I did a search on herr fuchs finger test and several different combinations like herr fuchs and finger test without luck. I found several references to the actual test but not a description on how to actually do it.

Also I´m wondering on how to remove the hydraulic compensators? Is there a special trick to it?

Happy motoring and thanks again,

Mikael Westerberg
1984 500 SEL
Vanersborg, Sweden

Anyone that knows how to do the Herr Fuchs finger test?

Thanks/ Mikael

Here is the Herr Fuchs finger test:

Helps to have a remote switch for the starter.

For each cylinder, place the cam lobe pointing up. Slide your index finger between the bottom of the rocker and the ridge of the ball stud. Mentally note the gap - like 4 mm. Now rotate the cam lobe down. Feel the gap. If it changed more than "a little bit," the HLC is weak.

After you have done a few, you get a better feeling for what the gap should be.

Note that if the rocker is down - like only a 1 mm gap - with the cam tip up, it is collapsed.

You need a 24 mm (I think - check this first) deep-well socket to remove the ball studs.

__________________
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe

Hi Guys

Thanks for the input, obviously a fairly common problem. Have been through all the checks including removing and inspection of all the HLC’s and the cam lobes and rocker arms, all look good, I even replaced the ball bearings in the piston non return valves and performed a bleed down test on each HLC, also performed the preload test ( 1.2mm to 2.4mm ) all fell well within, actual measurements ranged between 1.5 to 1.8 which would seem to be the ideal settings, I still have my ticking noise ( bugger ) What next, well the only things I can think of are the following

1. Some time in the car’s colorful history one or more of the old style HLC’s may have been fitted ( these I understand had different preload settings ( 0.7 to 1.9 ) in which case I have at least one case that comes very close to the max.
2. One of the oil supply holes in the head to the HLC’s is partly blocked and preventing that particular unit from attaining full pump up.

Either way they will all have to come out again ( bugger again ) I will find it eventually, as this noise spoils an otherwise quiet running engine, besides it’s now got me really miffed and I am not going to give up. Am now becoming an expert at removing and replacing the valve covers, especially the rubber seal. minutes.

Regards
BobH