M116 engine tapping noise - blocked oil channel?

[Fast_Lane_Dane]

Hi, I'm the happy owner of a w126 380 SE from -82 which has done 140 k miles. the V8 M116 engine has a knocking/tapping noise at cold start, which disappears after the first 2 miles or so. I have changed 4 of the 8 hydraulic valve lifters on the left bank of the V, where the noise is coming from, but the noise is still there. Apart from the tapping noise, oil pressure, temperature, idle/revving and all is OK. I've heard from another 380SE owner with the similiar problem that he've changed valve lifters, cam shafts, valve shims and all without getting rid of the noise, and that he had been told that it could be due to a blocked oil channel (don't know if that's the correct tech term). Have any of you out there heard about the oil channel issue before?

Thanks, Hans

 

[GEORGEROV]

Hi Hans, I have a 500se with the same characteristic , solved by using a thicker oil. I use a 15w-50 and this keeps the lifters quiet on start up. I realise you've changed the lifters but with the general wear and tear on a high mileage engine the standard specs for the engine change. I've been using the 15-50 for the last 6 years and engine still as sweet as a nut @ 180,000.

 

[Fast_Lane_Dane]

Hi Georgerov,
Thanks for your reply - I will follow your advice and see if it cures my engine - your M117 and my M116 are almost identical in construction, so if it worked for you, it should work for me as well. I'm considering to do a "residue flush" with one of those additives that you pour in the oil, let the enging idle for 15 minutes, then change filter + oil. My mechanic (who I trust - rare ;-) has done
it to his own W124 300E with good result = clean valve liftes & all + engine actually running smoother. I'll post the result and the brand of the fluid if it does any difference to my engine.

Cheers, Hans

 

[Blakey]

What's your oil consumption like?

On my old 124 I was getting through about 1 litre per 1000 miles and had noisy valves. Decided to change the valve stem oil seals. Oil consumption and valve noise went right down and engine performed as new. Not bad for 140K on the clock.

 

[Fast_Lane_Dane]

Hi Blakey, oil consumption is 'round 1 litre / + 2k miles, which should be pretty OK for a M116 V8 with +100 on the clock. The M116/M117's (and the older 350/450 V8's as well) are a bit thirsty when it comes to oil (as the Irish are with Guinness, eh? ;-) ), so I'll think I'll try the solution mentioned above up front - but thanks for the hint

Cheers,
Hans

 

[Fast_Lane_Dane]

I gave the engine a treatment with a product named smog doctor (only available to workshops etc.). It worked remarkably welll and cleaned the engine for residues etc.
New oli filter + 8 ltr of 15-40W oil and then off. But: The tapping noise when engine is cold didn't disappear :???:
I took the car to the Merc doctor - diagnose: grooves in left camshaft :sad:
So, new camshaft + rocker arms + valve lifters + oil pipe mount kit on the way from Germany. The only upside is that the price for the parts is a third of what MB in DK charges. Btw., I ordered the spares from carmaster.de, highly recommened father-and-son company with excellent service and MB understanding - I did though get the impression that they speak German only.
I'll return on this thread when the camshaft and other has been replaced and the tappping noise by then hopefully is a thing of the past.

Regards, Hans

 

[television]

Thanks Hans for the continuing update, it helps others so much when the cure is posted