Hello
Ive got a high pitch squeal that started up a couple of days ago. Starts squealing right on startup and never stops. Doesnt appear to be related to engine speed, and its not the AOS because I changed it and no change....although it sounds like its coming from that general area.
Any ideas??? Ive read other threads about it possibly being the water pump and that was also my initial thought. However the noise sounds like its coming off the top of the engine around the starter.
There's vacuum lines in that vicinity that maybe got damaged or disconnected when you worked on the AOS.
Is said squeal constant? Does it change pitch or speed with RPM? As for the water pump pull the rear firewall pan, run it, observe it.
Have you checked the fluid level on the power steering reservoir?
You may want to remove the drive belt and briefly run the engine, if the noise stops, then is something that is driven off the accessory belt (O2 pump, belt idle pulley, power steering pump) etc., etc.
Took the belt off and the squeal was still there. Changed the plugs, torqued to spec...squeal is still there. Starts out like a chirping bird, and then goes to a constant loud squeal after a few seconds. Maybe the new AOS is bad? Running out of options and I DONT want to take it to the dealer....
oh and squeal is not RPM dependent. Stays the same pitch no matter the engine RPM
When you removed the belt, did you turned each one of the accesories by hand ((including the tensioner and the idle pulley's?
I took the belt off and ran it momentarily without and the squeal is still there. So its a little colder here in Florida and now it takes a minute or two for the squeal to start. So this must be a heat issue. The sound is very loud and coming from the area around the AOS. I have already changed the AOS (twice) and that isnt the issue. I unplugged the secondary air unit
next
to the AOS and that wasnt it. No codes.
Really stumped on this one
But did you turned the pulleys, and each of the accesories by hand to feel smooth movement (and no play) from their bearings..?
I believe since he had the noise with the belt off - and these accessories not turning, we can safely take accessory belt-driven components out of the search pattern.
OP - a question: Does it do this with the car stationary?
If it only happens with the car moving that would make me think about something driveline-related, especially since it isn't related to engine speed. Do you own a mechanic's stethoscope? That might be quite useful in tracking the noise down, especially if the engine covers are removed. They're quite inexpensive at Harbor Freight in the US - and a much-used tool once you get one.
For example - my Cayenne has a tap noise from the engine compartment that sort of sounds like something bad (collapsed lifter, bore breakdown, something ugly). Chasing the noise around the engine compartment led me to the electronic vacuum line that is used to purge the charcoal evap-canister. The valve opens on an almost regular interval, but not quite, and it's generally not related to engine speed - but it's harder to hear with higher engine speeds. The noise also goes away when the turbos start kicking in and pressurizes the intake manifold that the valve is connected to.
The mechanic's stethoscope led me right to it - and it turns out it was entirely normal. It's a noisy little bugger, rubber mounted to try to quiet it down. Mercedes uses the same valve - they put theirs in a foam-lined box to quiet it down. I've learned to ignore it, thanks to the stethoscope.
I actually finally figured it out. Turns out it was the ECV valve that sits just behind the AOS on the passenger side. Its tucked away under the back so I didnt even see it. When I pulled the vacuum hose off the top it stopped making the noise. The sound is so loud you cant hardly talk over it if you are standing
next
to the car. Hope this helps someone else in the future...certainly a weird issue for me.
