strange engine noise

PONTIAC TRANSPORT
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LJYAROS
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I have a 97 Pontiac Transport with 138,000 miles. I noticed today when under the hood while it was running that the engine sounds like it's leaking air like a flat tire. It has also been idling rough the past few days. Any idea what it could be?
Jul 20, 2006 at 10:00 PM
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MIKEYBDMAN
  • ✓ASE Certified Mechanic
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  • ASE Certified Mechanic
Rough idle plus hissing noise usaly mean vacuum leak. I would look at all of the vacuum hoses atteched to the throttle body and follow them to their respected valves. Dont forget to look at the one that leads to the transmission.
Jul 21, 2006 at 3:17 PM
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