Hey folks,

Any idea what would cause a ticking that sounds like nails being dropped on a chalkboard sound coming from the engine bay? It just started a couple days ago (and now for the weird part) it only occurs in gear at 1200 RPM. If the car is in park or neutral there is no ticking, but once warmed up it will tick only at 1200 RPM in gear.

If it was a gasser I would say it was spark knock/pinging. No bad vacuum pump symptoms (brakes, locks, etc work fine)

Glenn

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2012 Mercedes ML350 Bluetec 102K (hers)
2005 Corvette 55K (fun car)
2002 VW Jetta TDI 238K (mine)
1998 Volvo S70 T5 Turbo 211K (kids)
1994 Ford F150 4WD 246K (firewood hauler)
1983 Mercedes 300D 384K (diesel commuter)