New noises and vibrations

[John Larkin]

Last 2 times I've started the car, I've had cold start knock for 2 seconds, then it clears. It's a very light tapping like a lifter. Upon restart, it never does it again; I have to wait for it to be full cold to hear it. Oil is basically clear, PF52 filter, 500 miles on oil change using 10W30 organic and it's halfway up the hatched portion of the dipstick. The oil did have somewhat of a gas smell to it, but maybe that's just my imagination. Any thoughts as to resolution?

Also, turned on the A/C last night idling in park. I felt a vibration, particularly through the brake pedal. Checked the unit and belt tension is good and the unit seems secure. Maybe it's just due to A/C not being used for months and will clear once used regularly. Again, any thoughts appreciated.

 

[speedy1320]

John, I don't know about your AC scenario, but what you describe at start up sounds exactly LIKE a lifter! A bad lifter can bleed down prematurely and when you start your engine you are hearing the "click"of the gap between it and the cam lobe until it "pumps" back up. Obviously if you re-start you car soon after, the lifter isn't "bled" out yet...

A mechanics' stethoscope might be able to confirm this...

Good luck

Tom