Mercedes SL Class Mercedes SL500 and Mercedes SL600 Roadsters.

Engine knocking noise

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  #1  
Old 12-21-2007 | 03:47 AM
padima's Avatar
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Default Engine knocking noise

I have a knocking noise on the right side of the engine. It's quite strong at low rpm and, as soon as you rev up, it disappears. We tried compression to see if it was a piston, but the difference between the 8 cylinders is insignificant. All plugs are worn at the same way, same color, no oil anywere. I counted the hits of the noise and I came up with approx 360 knoks per minute with the engine at idle (one every two cycles). As the engine was running we disconnected power to the plugs of one cylinder at the time: no change. We took the cover of the lifters off and, turning the crank manually, we set every single valve to the cose position: no play at all, even pushing down the lifter to see if there is any loss of oil pressure. The rollers that ride the camshaft are ok, they show no play. Thecar has 180,000 Km and burns one quart of oil every 5,000 Km.I have run out of ideas. Can you help me?
 
  #2  
Old 01-08-2008 | 04:40 AM
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Default RE: Engine knocking noise

wow, good one. It's a knock and not a loud tick? lifters don't usually knock andif not a connecting rod.[&:] have u used a stethoscope? please tell what u find in the end.
 
  #3  
Old 01-16-2008 | 02:05 PM
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Default RE: Engine knocking noise

Its a knock and not a tik. Tried everything including stethoscope. Next week we'll take off the oil pan try if there isplay on any of the connecting rod and check if any of the cylinder shows grooves. After that, I'll wait untill it cracks. I had enough.
 
  #4  
Old 01-27-2008 | 04:09 AM
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Default RE: Engine knocking noise

No fix!!! after having changed all connecting rods bushings, checked if there was any play pushing up & down and sideways each one of them, we found NOTHING. Took apart the lifters pack: perfect, no oil loss, none sticking. Riassembled everything, Still Knoks. Nice eh!
 
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