Question I have a 2005 Chrysler Crossfire. The engine is a 3.2 L M112 E32 V6 Mercedes (as in the SLK 320). The car has 68,000 miles on the odometer. My major problem is the knocking sound that can be heard at low engine speeds (idle). The sound decreases as rpm's increase and disappears completely at around 800 rpm. It’s very hard to pinpoint where it is coming from. Also the clicking sound seems to quite some when the air conditioner is on. I use 0W-40 Mobil-1 and Mann fleece filter.
The engine runs great. I have been told by a Chrysler dealer it is the air pump and is normal for this engine. I was also told by a Mercedes dealer it is the fuel injectors and again was told it is normal for this engine. If Chrysler and Mercedes would agree on the cause I wouldn’t be concerned. The valve train has been checked out and no problems there.
The knock is not only annoying but I am concerned that it could be damaging the engine. If this knocking (clicking) is normal for this engine can the idle speed be increased? That at least would eliminate the worrisome knocking.
Answer Hi Don,
The idle speed is controlled by the PCM and usually cannot be changed.
The noise might be being eliminated by a slightly higher oil pressure when the rpm is raised a bit. So one thing to try would be the next higher "weight" of engine oil at your next oil change.
If you could listen with a rubber hose to localize where the sound was coming from that would be helpful. The air pump is external and can be changed out if you verify that is the source.
I have the '05 manual on a CD and can share any pages you need as attachments to an email I would send to you directly.
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