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GMC Expert, ASE Certified Technician
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Experience:  30 yrs experience, ase certified, shop owner
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2001 Alero: GLS..V6, Squealing noise..losing power..Vacuum leaks

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2001 Alero GLS, V6, Squealing noise during acceleration and losing power at higher RPM. Checked for Vacuum leaks and replaced MAF and MAP. Problem still there.
This is very commonly a faulty idler pulley or tension pulley , remove the serpentine belt and tell me if the noise goes away
Customer: replied 6 years ago.
Already did that and still have the same noise

Okay any other too common areas for this to come from is either the intake manifold Being a vacuum Leak . All often the PCv valve may be faulty causing this problem , and sometimes the front transmission seal will squeal and making noise

Start the engine so that makes the noise and remove the oil filler cap tell me if the noise goes away

Customer: replied 6 years ago.
Did what you said and it didn't go away. It sound like its between the MAP and EGR area.

Yes this is most likely going to be either like I said a faulty PC the valve or a leaky intake manifold gasket . If you had a smoke machine would be able to track it down a little better .

If you spray the area where the noise is with carburetor cleaner does the engine speed or idle quality change at all ?

Customer: replied 6 years ago.
What do you mean about quality change? the sound gets louder? Can I use electrical cleaner to spray... I don't have carburetor cleaner.
It would be safer to use carburetor cleaner, what I mean by quality is does the idle get rough or smooth out or faster or slower
Customer: replied 6 years ago.
ok, i'll run down to walmart and get carburetor cleaner. There is one time I sprayed soapy water in around the Exhaust Flange Gasket (In that area) and the noise got louder and I didn't have to use the throttle to hear the noise. While sitting idle the car runs good. I'm going to get the carburetor cleaner... will be back.Felpro/Exhaust Flange Gasket nge Gasket Exhaust Flange Gasket
ok thanks
Customer: replied 6 years ago.
got the carburetor cleaner and sprayed in the area of the noise and no changes.

get a 3 foot piece of hose , place it near your ear and use it like a stethescope , slide it down under and try to pinpoint the origin of the noise

Customer: replied 6 years ago.
tried the hose, couldn't pinpoint the noise. But it sound like it's below the coil and MAP. There is a hose going into the exhuast manifold (below the coil) coming from the air intake. It pops out really easy. What is that hose for?

If you could take a picture of it and send it, that would help tremendously

Customer: replied 6 years ago.
o.k. I will but its dark now..... I'll change the reply thing to give us more time. You will receive the picture tomorrow morning early.
OK thanks
Customer: replied 6 years ago.
I should be here whenever you would like to send the picture thank you
Customer: replied 6 years ago.
That is just simply a crank case vent tube , this two should not be hooked to the exhaust manifold as you said earlier, there is a pcv valve located in this area that you're describing which is very commonly will make the noise or describing. Get a new pcv valve and grommet from the dealer not from the local parts store. For some reason the valves I've gotten local lee from the parts stores have also made noise because the listing is not proper and the catalogs
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Customer: replied 6 years ago.
Customer: replied 6 years ago.
I will get the PCV valve and grommet. If it isn't the problem, I will replace the gasket air intake manifold.
Customer: replied 6 years ago.
What about fuel injectors will that cause the problem with the noise and lack of power in higher rpms
The injectors could be causing a lack of power, but be very honest with you we need to solve a vacuum leak / noise first because that could be your lack of power also

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