fan??
#1
09-30-2011, 06:46 AM
fan??
so I was wondering if anyone can tell me what the sound is when I first start going and it sounds like a extra fan is kicking in? It only lasts until I get roughly out of first gear but its pretty loud and and doesnt happen all the time..once the vehicle is warm it wont do it...it doesn't seem to hamper anything but it is pretty loud.....just curious? btw its H3 3.7 adventure
#5
10-02-2011, 09:36 PM
I have the same sort of noise, but definitely not the fan clutch (that's a different sound). This sounds more like another small actuator or motor, seems to come from the passenger's side, could be in the truck or under the hood. Tom might be on to something with the small compressor. However, just on startup and not all the time.
Didn't have this with my '06 or '07 I5, nor with the '09 V8.
Didn't have this with my '06 or '07 I5, nor with the '09 V8.
#6
10-03-2011, 01:27 PM
I can also look into this for you. In order to do the research, I would need the last eight of your VIN. Thank you in advance.
Tricia, GM Customer Service.
Tricia, GM Customer Service.
#7
10-04-2011, 08:06 AM
I have the same sort of noise, but definitely not the fan clutch (that's a different sound). This sounds more like another small actuator or motor, seems to come from the passenger's side, could be in the truck or under the hood. Tom might be on to something with the small compressor. However, just on startup and not all the time.
Didn't have this with my '06 or '07 I5, nor with the '09 V8.
Didn't have this with my '06 or '07 I5, nor with the '09 V8.
#8
10-04-2011, 08:45 AM
Likely the brake booster pump. It is a small air pump run by an electric motor. Not a roar but loud enough to hear in the cabin.
Last edited by RKSmith163; 10-04-2011 at 08:47 AM. Reason: Additional Information.
#9
10-04-2011, 03:19 PM
The pump is used instead of vacuum boost. If you have the same service manual that I do, it is item 24 in the parts list labeled as Power Brake Booster Pump ASM Motor under the Antilock Brakes section. Following are quotes from the same manual regarding this.
Page 47
"The ABS pump motor recharges the brake fluid accumulator during antilock braking and normal power brake assist. The ABS pump motor is part of the hydraulic brake booster assembly."
Page 49
"Circuit/System Description
The ABS pump motor and accumulator operates the ABS and base brake power assist systems. Pressurized brake fluid is stored in the accumulator and used for ABS and base brake power assist functions. An accumulator pressure sensor located internally in the electronic brake control module (EBCM) monitors the accumulator pressure. If accumulator pressure becomes too low, the ABS pump motor is commanded ON."
This is what some may be hearing especially if the truck has been sitting a while.
#10
10-04-2011, 04:44 PM
i wondered how they got power brakes out of that "mess" in the brake area. thats a fluid pump that pushes fluid up into the "tank" which must have air in it so it gets pressurized.
thats not the roar that we hear sometimes,it varies with engine rpm,just sitting still. the brake pump runs when pressure is depleated.
funny i could not make mine roar,cold start,revving engine this morning.
i dont know if my obd2 scanner will show that fluid pressure,but i will find out. if it can be observed running down,and coming up with pump action i should know when its running and then maybe hear it,,,??
i am curious why the fan only roars,,,when it wants to!!
thats not the roar that we hear sometimes,it varies with engine rpm,just sitting still. the brake pump runs when pressure is depleated.
funny i could not make mine roar,cold start,revving engine this morning.
i dont know if my obd2 scanner will show that fluid pressure,but i will find out. if it can be observed running down,and coming up with pump action i should know when its running and then maybe hear it,,,??
i am curious why the fan only roars,,,when it wants to!!