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2005 Chevy Cobalt Car running hot and making a vacuum noise

Tiny
WRE06
  • MEMBER
  • 2005 CHEVROLET COBALT
  • 4 CYL
  • FWD
  • MANUAL
  • 65,000 MILES
Around two weeks ago my car started making a vacuum noise under load. The noise sounds like air leaking somewhere, if I accelerate with out downshifting the noise becomes very pronounced. Also, around the same time my engine started running much warmer than normal. I have no codes but my coolant gauge, which historically reads 187-190, now approaches around 220 every time I enter stop and go traffic. Could these be related? I checked the intake, and no holes are evident, and the seal from the intake to the throttle body is tight. I do have a slight oily residue on the inside of my throttle body, I'm not sure if this is normal. I checked the PCV system, and it appears to be operating normally.
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Thursday, December 18th, 2008 AT 5:30 PM

3 Replies

Tiny
BUDDYCRAIGG
  • MECHANIC
  • 2,262 POSTS
Is your idle any higher?

You are describing a vacuum leak.

There are many ways to check for a vacuum leak.
I use a propane torch BUT DONT LIGHT IT.
I move it around everything in the intake system and hoses.
If you get to a spot that the engine rpm changes, then you are really close.

Then I stick one end of a 3 foot long hose in my ear and move the hose around in that area until I can hear the sucking sound.

Good luck
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Thursday, December 18th, 2008 AT 9:20 PM
Tiny
WRE06
  • MEMBER
  • 4 POSTS
I was not able to locate the leak using the described methods. Any other suggestions? Is an oily residue inside the throttle body normal?
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Tuesday, February 3rd, 2009 AT 3:51 PM
Tiny
BUDDYCRAIGG
  • MECHANIC
  • 2,262 POSTS
Find a repair shop that can do a "smoke test"

they blow pressurized smoke in to the suspect areas and the smoke will come out the leak.

Should cost $80-$100.
But that's a lot cheaper than the machine.
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Wednesday, February 4th, 2009 AT 12:08 AM

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