Hey guys, I've started getting this strange whine on my Evo VII.

It sounds like a pump-type whine coming from the drivers side (RHD) engine bay. The sound will start randomly whilst driving and the engine is still cold. What's strange is that it will only happen when the car is moving. As soon as I come to a stop the sound disappears. It's a constant whine that doesn't change pitch with rpm or speed. It just starts randomnly while moving and stops when the car becomes stationary.

You can hear the sound in the video below from the beginning. You'll notice that I coast for a bit and then increase RPMs but the sound doesn't change. When I stop it disappears and when I start moving again it doesn't reappear. It will however reappear randomnly some time later.


I'm wondering if my power steering pump is going bad. I did have the resevoir running really low and didn't realise till I was getting an RPM dependent whine (different type of sound) on hard left turns. I refilled the resevoir and bled it but have started getting this new sound. Though the sound doesn't change when I turn the wheel so not certain its the power steering.

 

Louder with the back seat cushion removed?

 

I did suspect the fuel pump, its a walbro 255.
Drove to work today with the back seat cushion removed but the sound wasn't louder and was definitely coming from the front. It only happens maybe twice when the car is cold, once it's warmed up I don't hear anything.

Unfortunately I can't get in to the engine bay to hunt the sound because as soon as I stop it goes away but it does seem to be coming from around the power steering pump area. I can't figure out what kind of sound would be dependent on the car moving or being stationary.
Any ideas?

 

My car didn't have active diff so don't know how that works. Maybe that pump? Anyway it sounds like pump noise to me.

 

The AYC pump does make a bunch of noises but with the back seat removed I could hear it clearly in the back. This noise is definitely from the front. I'm at a loss.

Might try lubricating the moving parts on the power steering assembly. Had no one ever come across this noise?

 

So I may have to eat my words. I tried to stick my head in the back when it made noise and I think it oculd be coming from the rear. It's hard to tell, the sound seems to bounce around in the cabin.

The AYC or ACD pump would align better with the evidence. I'll try to see if I can figure out how to disable the pumps to confirm. But if it is the pumps making the noise what does that mean? Are they on their way out?

 

I cant speak for the ACD pump but thats what the AYC pump sounds like. Sometimes a fluid flush is all you need. They aren't the most durable part, and get noisy when cold. There is a fuse on the 4-6 on the positive battery terminal for the AYC pump. I think it's the same on a 7. Pull the fuse for a day and see if the noise returns.

 

So I disconnected the relay under the bonnet that supplies power to the AYC/ACD pump assembly (next to the 4WD ECU) for the drive to work this morning but the noise was still there.

I couldn't for the life of me tell whether it was coming from the front or rear. But with that relay disconnected that rules out the entire AYC/ACD system right? Unless I'm missing something?

 

how can I disable my power steering pump? See if I can rule that out.

 

So thought I would share the resolution for this issue.
Had to drop it off at a workshop because I couldn't figure the noise out, tuns out it was a failed bearing in the AC fan causing the noise. Swapped out the fan, problem fixed.