I have a 1986 190E 16V with about 16k mi on a rebuilt engine. The car has been properly service since the rebuilt. I have notice a knocking noise comming from my engine lately and it is driving me nuts. I use a 91 octane fuel. I only notice the knocking noise when I drive under normal condition W/O ac on very hot days +90F. I did a search on knocking and pinging and found some answer, but did not find anything about 16v. Pleaes need help!!

Eddie 16V
86-16v Smoke Silver
European Headlights, backseats
Clear Corners
17inch AMG Monochrome rims/tires
automatic (great car in the LA area)
Sony head unit w/ 10 discs CD changer,amps
2-8inch sub woofers

The belt tensioner has a shock absorber that can really cause knocking noises!!

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190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

I replace the shock on the belt tensioner in fact that is when I notice the knocking noise
Eddie 16v

Is the knocking only at a certain RPM. My car knocked LOUDLY at around 850-950rpm. Popped the hood, looked at the tensioner as I slowly revved the engine, sure enough, the tensioner was vibrating quite a bit. Replaced the damper on the tensioner and it took care of the problem. The tensioner now is as smooth as can be, and the knocking is gone. Not sure if it is the same set up on the 16v, but thought I would offer my fix.

The knocking noise occurs when I really step on it? And the knocking noise doesn't always happen, but it only happens on hot days
Eddie 16v

If it only happens on hot days, does it also only happen when the fan clutch is engaged (you can hear the roar at higher rpm's)? Perhaps the fan is hitting something, or the bearing is going bad, allowing it to wiggle.

Steve

You might need a valve adjustment. If the knocking noise is coming from the engine.

Regards,
John

Hi,

Is the sound a physical rattle or is it pinging? You said that it happens on hot days when you step on it. To me, this indicates that detonation is happening. First, check the timing and make sure it's right. Check out the ignition computer, too, as it has the capability of advancing the timing. Also, make sure you have the right spark plugs...the wrong ones can cause detonation.

Hope this helps!! Let us know how it goes!

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87 190E EVO II Turbo

I want to thank everyone for there inputs.I will be at my MBZ mach this comming Monday, So with the info in hand we will try to fix the problem.Again thanks.
Eddie16V

Eddie

I thought the 16V needs 93 or higher octane fuel. You mentioned you are using 91.

These 16V frequently demand our attention and while I've fixed mine I've never determined what I did to fix it. I've always got idle stabilization problems. It idles fine for a few months, then it doesn't. I unplug everything, everything checks okay, I put it back together and it runs fine ... for a couple months.

I had some knocking in my 16V on hot days while AXing. My mechanic gave me a can of BG44 or whatever the name of it is to add to the fuel (cleans injectors and valves). Haven't noticed any knocking since.

Robby