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Vacuum noise when idling.

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Old 07-16-14, 10:59 PM   #1
Gerb
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Default Vacuum noise when idling.

I was watching someone park my car and i heard the engine make a vacuum like noise. Anyone know what it is. It lasts for like 5 seconds only. We got a mechanic to check the car before we bought it 1k km ago a month
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Old 07-17-14, 03:19 AM   #2
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Sounds like the A/C compressor turning on to keep the engine cool. If so, then that's normal.
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Old 07-17-14, 08:40 AM   #3
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Does the car have an intake? that is the only vacuum noise loud enough to hear from outside the car other than the a/c compressor.
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Old 07-17-14, 09:09 AM   #4
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Many cars have air injection pumps that kick in on cold starts for a few seconds (all for emissions). I dont actually know if the IS models are equipped with this (im sure someone can confirm this here) but i think the GX, and most of the 4.7/5.7 Toyota V8s had the injection pumps. They commonly failed on the Tundras.
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Old 07-17-14, 11:35 AM   #5
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Nope no intake, Probably a/c compressor. Its really on and off normally on starts or when u turn it off.
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Old 07-17-14, 01:01 PM   #6
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If it is truly a vacuum leak, a truly impressive and easy-to-do DIY fix is to get yourself a fog machine and let the fog loose in the engine bay. See where the fog is sucked up into the motor anywhere else other than the air filter.

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Old 07-21-14, 03:29 PM   #7
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has the car been idling for awhile? It might be the fan.
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Old 07-21-14, 04:08 PM   #8
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EVAP system.
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Old 07-21-14, 04:08 PM
 
 
 
 
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