Loud squeaking on a 93 gmc k1500
#11
02-27-2016, 07:00 AM
I once had a problem with a loud knocking sound coming out of the engine compartment. It would only make the noise when the AC was engaged. The sound seemed to be coming out of the compressor. Turn off the AC and everything was quiet. I picked up a new compressor, charged up the system and turned it on. The knocking came back immediately. Boy was I confused.
I then did what I should have done in the first place. I got a long screwdriver and placed the handle against my ear and probed the compressor with the other end. Very quiet. I probed the power steering pump which ran on the same belt and was directly below the compressor and the knocking was very clear. Changed the pump, fixed the problem. What that taught me was that the increased load on the belt caused by the compressor being engaged transferred the strain to a weak part, the PS pump.
I don't know if any of this applies to your problem but tracking noises can be tricky. Good luck and let us know what you find.
I then did what I should have done in the first place. I got a long screwdriver and placed the handle against my ear and probed the compressor with the other end. Very quiet. I probed the power steering pump which ran on the same belt and was directly below the compressor and the knocking was very clear. Changed the pump, fixed the problem. What that taught me was that the increased load on the belt caused by the compressor being engaged transferred the strain to a weak part, the PS pump.
I don't know if any of this applies to your problem but tracking noises can be tricky. Good luck and let us know what you find.
#12
02-27-2016, 10:17 AM
It could be the tensioner but the belt is new. It also makes the loud noise the entire time the truck runs, with or with out the AC running... I'll get my stethoscope out today and try to do some investigating.
#13
02-27-2016, 10:20 AM
I also forgot to tell you guys that the NEW compressor, when engaged, sounds like it has gravel in it. When it's off the pulley runs smoothly but when I turn it on and the clutch engages the compressor makes a loud grinding noise.
#14
02-27-2016, 05:53 PM
Replaced the belt and tensioner today which quieted the compressor quite a bit (no more sounding like gravel) but the loud squealing is still there after the truck gets warmed up. It is also throwing code 43...
#15
02-27-2016, 07:34 PM
CODE 43
Trouble Code 43 indicates that there may be a malfunction in the Electronic Spark Control (ESC) circuit. ESC is used to sense spark knock (pinging) and retard the timing to eliminate it. The knock sensor is located at the rear of the engine block. The ECM will retard the timing by as much as 20 degrees in 1 degree increments. A loss of knock sensor signal or loss of ground at the ESC module will cause the signal at the ECM to remain high. The ECM will act as if no knock is present, and
may possibly result in engine damage, due to detonation.
Code 43 is set when:
? Voltage at Knock Sensor is above 4.8 volts or below .64 volts.
? Either condition is met for about 10 seconds.
Possible causes:
1. Open or shorted knock sensor
2. Loose knock sensor
3. Excessive mechanical noise within engine
4. Improper or incorrectly installed MEM-CAL in the ECM or defective ECM
5. Intermittent open in the EST line to the ignition module
Trouble Code 43 indicates that there may be a malfunction in the Electronic Spark Control (ESC) circuit. ESC is used to sense spark knock (pinging) and retard the timing to eliminate it. The knock sensor is located at the rear of the engine block. The ECM will retard the timing by as much as 20 degrees in 1 degree increments. A loss of knock sensor signal or loss of ground at the ESC module will cause the signal at the ECM to remain high. The ECM will act as if no knock is present, and
may possibly result in engine damage, due to detonation.
Code 43 is set when:
? Voltage at Knock Sensor is above 4.8 volts or below .64 volts.
? Either condition is met for about 10 seconds.
Possible causes:
1. Open or shorted knock sensor
2. Loose knock sensor
3. Excessive mechanical noise within engine
4. Improper or incorrectly installed MEM-CAL in the ECM or defective ECM
5. Intermittent open in the EST line to the ignition module
I wonder if your whistle noise isn't a vacuum leak?
#16
02-29-2016, 07:44 AM
I found that the clips on my knock sensor pigtail had broken off so it wasn't seating properly which was causing the code. I ruled out the water pump and fan clutch yesterday also. My power steering pump is now the only accessory I haven't replaced in the past month and it has a lifetime warranty so I'm going to swap it out today. If that doesn't fix it I'm not sure what will...
