What's causing my vacuum leak?


Asked by Apr 14, 2015 at 12:37 PM about the 2000 Mercury Cougar 2 Dr V6 Hatchback

Question type: Maintenance & Repair

I have a 2000 Mercury cougar  v6.  Whenever the outdoor temperature is below 75
degrees and i go more than 45 mph, a vacuum leak opens up causing a host of issues
(including failure of the vacuum assist breaks), but once the engine warms up, the leak
closes and the car drives fine.  Because it's so sporadic, neither me nor my mechanic can
find the leak. What are the most likely culprits to be causing this?

1 Answer


Update: I replaced the IAC which helped a little bit, but didn't eliminate the problem. I have also noticed that the engine will rev ( usually up to 2500 rpm) whenever I use the brakes.

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