Impeller Whine

[Ski]

Ok so I asked the question about a whistle, and I really thought it was an air leak of some kind but maybe not. Here is what I have learned so far. This whine, or scream, increases and decreases with engine revolutions. As I accelerate through my gears, it will increase in tone (not volume, its loud as ****) but as my transmission shifts it will change "down" in tone, So I stopped my truck and popped the hood to listen to it at idle. Now it only seems to do it at specific RPM's, not at idle but as I increase the RPM's to about 2K. The sound is definitly coming from the front of the motor. Around the water pump. That is what led me to believe the impeller in the pump might be going. However, I didnt think it would increase/decrease with engine revolutions if that was the case. But it is definitly coming from that area, water pump, thermostat, possible altenator(however I doubt that). My check engine light is still on even with me plugging the air leak. I think that is a seperate issue though. So first things first, what is this whine/scream? Your thoughts???

 

[Roadkill]

Sounds like possible a bad bearing in one of the engine accesories. The tension wheel for my serpentine belt went bad a few years ago and that made quite a racket that varied with engine RPM as yours does. Any of the components could display a similar whining noise that varies with engine speed. Try taking off your belt, then spin each of the pulleys by hand. (also check if they have any play in them) They should all rotate smoothly and not wiggle around on their shafts.

 

[Ski]

Sounds like possible a bad bearing in one of the engine accesories. The tension wheel for my serpentine belt went bad a few years ago and that made quite a racket that varied with engine RPM as yours does. Any of the components could display a similar whining noise that varies with engine speed. Try taking off your belt, then spin each of the pulleys by hand. (also check if they have any play in them) They should all rotate smoothly and not wiggle around on their shafts.

Doesnt the fan and associated equipment (ie. Altenator, water pump, air conditioning) spin at a constant speed, independent of the engine output? In other words it shouldnt increase and decrease with the RPMs of the engine right, or the transmission?

 

[Roadkill]

Nope. That stuff is all driven by a pulley on the end of the crankshaft. Engine speeds up, everything speeds up. There are other systems to control the output of the accesories, if nesesary.

Example: voltage regulator limits alternator output to about 13.8 volts regardless of how fast alternator spins.

 

[wtfdissux]

to narrow down a little more remove the belt and start it up if its gone its external (water pump, alt power steering pump and so on) if it is still there it is internal (main bearing timing chain cam gear and so on)

if it is external USING EXTEME CAUTION start it up after re-installing the belt use a long extension as a stethoscope holding one end to your ear(not in or on your ear with your hand like it was a glass against a door you are trying to hear thru) on a NON MOVING part such as the alternator housing or the center bolt for the tensioner when you get to the right part you will know and after your ear stops ringing and you can hear again get down to the local parts store

 

[Ski]

Ok so when I put my A/C on the whine/scream goes away, or so it would appear. But here is something else, I got the codes read, P0171 and P0174.

Anybody have a thought?

 

[Roadkill]

If it goes away with the AC on, sounds like the AC clutch is going bad. The clutch assembly allows the AC pulley to spin with the engine without driving the compressor. When you turn on the AC, it engages the pulley to the shaft and drives the compressor. They cost about $100 (a lot cheaper than a whole new compressor). Not sure how hard it is to change since I've never done one myself. I don't know what the codes mean, I'm a very long way away from my manuals right now.