Engine/Transmission (1998.5 - 2002) Idle Oscillation

[GOLDENCANTINA]

Once truck is warmed-up and in Drive, I notice a faint idle oscillation when stopped. Noise only noticeable at idle. Sounds like its coming from right side of engine. Fuel pressure fine.

 

[AH64ID]

a/c compressor?

 

[GOLDENCANTINA]

A/C Compressor not in-use (not hot here yet).

 

[AH64ID]

Is your defrost in use? The defrost uses the a/c compressor.

 

[ALepley]

Its either the a/c compressor or the intake heater kicking on causing a draw. Whicjh are the normal that can cause the idle to change.

 

[Vaughn MacKenzie]

AC compressor cycles on all but two HVAC positions

 

[GOLDENCANTINA]

Thanks for your inputs! Will switch Ventilation Control Knob to Off and listen.

 

[GOLDENCANTINA]

Sound isn't the idle, it's in the transmission only noticeable when Drive or Reverse is selected. When slowing to a stop the noise can be heard below 10mph. Sounds almost like a rotating shaft rubbing in one spot. It's barely noticeable. It's made the sound for a long time, and hasn't increased intensity. It reminds me of the lope a long duration camshaft would make in an engine.

 

[GOLDENCANTINA]

Betty's crew at Sutherland Diesel Perfomance isolated the noise to the alternator. Whew!