I have a sound under my hood that sounds almost like a hydraulic motor or something. It keeps with the RPMs and everything. I can't think of anything hydraulic that would be making that sound though. I checked my powersteering fluid just in case, but it's good. It doesn't sound unhealthy though(like when you're low on PS fluid and you turn the wheels) so I'm not too worried about it. I'm starting to wonder if it's not my belts. Anyone else notice this on their trucks?

 

Well, that's a bit vague, but no, I've never had a sound like that. I would not just ignore it, especially since you don't know what it is. Does it show up all the time, or just under specific conditions (turning the wheels, sitting at idle, upon acceleration, etc.)?

 

It's a constant whirring sound that keeps with my RPM. When I rev up, it gets louder, and when I let off the gas, it goes down-but never away. Thats why I don't think it's powersteering. I looked under my hood some more and it looks like the belt may possibly be just starting to show signs of age. Also, I was watching the pulleys, and there's to that seem to keep shaking from time to time. One's the idler, and the other is a bigger pulley near the bottom(I'm hoping it's not my crankshaft pulley!). They're almost like I have a bearing going out on each or something...except I don't hear that famous cracked bearing squeak. So I'm gonna take it to the shop and get a second opinion on those pulleys this weekend. If the guy says it's nothing to worry about, I'll just change the belt myself this weekend and see what happens.

 

Does this whirring noise occur in all gears? If it goes away in park and neutral its the torque converter

 

Nope, it's in all gears. I was able to leave the truck in park and look under the hood while it was doing it. It's coming from the front of the engine some where. That's why I'm hoping it's just the belt.

 

Check the AIR system 'T' under the crank pulley (look from underneath). It is possible that one of the check valves has failed in the AIR system and has burnt out the 'T' where the lines from Bank 1 and Bank 2 connect together before traveling to the AIR pump.

 

How would I know that it is bad without taking it apart? Or is that what I need to do? If so, it should be pretty quick to take apart with a wrench, right?

 

Ding! I just rememberd that I still have a warranty on the blazer! Time for a trip to the shop! Thanks for helping me pinpoint where it may be coming from-I'm gonna pass that info on to the shop. What is this AIR system? I take it AIR is an acronym for something? I'm trying to look it up on google to learn something new, but I can't find nothing.

 

The big one at the bottom is probably the harmonic balancer failing. I've never seen the AIR injection so I have no clue about that but between the two pulleys and the AIR that's a good start for diagnosis.

 

If the harmonic balancer started failing, wouldn't the engine start running rough?