Engine whine, louder with rpm increase.
 

Hey guys,

I've had this problem for awhile now and have had just about enough of it. I have loud engine "whine" when accelerating fairly hard in first gear and gets louder as RPM increase, and barely audible in the lower range of second gear. Then it's gone after that, even when I'm still on the throttle. The sound somewhat resembles a supercharger. The whine is only heard when under load, not sitting in neutral and giving it a rev.

I searched the forum but it seems the general problem is a fuel pump whine, which I don't think I have as I cannot hear it unless I'm accelerating.

It doesn't seem like a big problem because the truck still runs really well, it's just annoying and loud enough to be heard over my exhaust.

Any input is appreciated, thanks-

Justin
2003 Silverado 2WD, 4.8L

I would think it could be transmission related being as how you described it changing with gear changes.

Is it possible the transmission just needs to be flushed? I have 126000km on the tranny.

I'm not a huge fan of flushing the transmission. I would have the filter changed and fluid topped off. It may have been a coincidence but a Firestone dealer talked me into a trans flush as strictly a preventative thing (my transmission was 100% fine) during an oil change interval. Not even 2 days later the transmisson went out completely.
I would also check the fan clutch. My truck doesn't whine, but I can hear my fan when I accelerate from a stop and into the 2nd gear shift like your describing, but only when pulling a trailer (for some reason).

I would check the power steering fluid level. I have a W-body with the 3.0L and experienced a whining sound. On an edmunds.com discussion thread someone suggested the fluid level for the power steering was low. I read the owners manual and checked it. While the vehicle was warm, the level was barely where it should have been for a cold vehicle. After adding some fluid the sound went away. This happened after owning my LaCrosse for two year. I have never seen any evidence of a leak.

It could also be an alternator bearing whining. its not uncommon for it to go away as the tranny shifts up through the gears (this reduces the rpm load on the engine) I would look at the other suggestions given. the tranny flush is NOT a good idea! At 126000 i would look at a fluid and filter change......but I bet it is a alternator, water pump, power steering, or fan issue.

I don't like the tranny flush idea either. I've heard nothing but horror stories about flushing. It's like a killer for otherwise good running transmissions.

Thanks everyone. Now that you mention the fan clutch it just may be it, judging by the sound it's making. I will try to check the alternator bearing, but it doesn't sound bearing like, it's not high pitched at all, just on the loud side. I will also note the power steering fluid, I'll leave the tranny for last.

Is there a tested way to troubleshoot the fan clutch? Or just try to turn it when the truck's not running, or replace it.

Thanks,
Justin

The fan clutch should not have any "wobble" in it and should spin fairly easy when "cold" (3/4 to 1 revolution) while you are there you should "drop" the belt and check the water pump bearing too. I usually just ditch the mechanical fans and go electric.

Now that I think about it mine is more noticable when towing because I have the tow/haul button on and it turns a little more RPM's before shifting. DUUUHHHHH!!!!!!!!!! Sorry momentary brain queef!