Question about 1992 Ford F250

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Ford truck f250 v8 motor idles high after engine heats up it idles higher cant find a vacuum leak replaced a idle air valve it didnt help

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The vacuum leak that causes this high idle is the gasket at the bottom of the upper intake manifold runners, they **** in, done 100's. to confirm this just spray carb cleaner at inside and outside base, when u hit the leak you will hear it. see photo.

ford truck f250 v8 motor idles high - 29f44ce.jpg

Posted on May 10, 2009

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Most likely your leak is the "intake plenum" gasket. The easiest way to find a vacuum leak is to get a can of starting fluid, and spray it around the intake and vacuum hoses while it's running.
Be careful, starting fluid is extremely flammable!
If you notice an accelleration, or de-celleration while spraying the starting fluid you should be able to pinpoint your leak. I have seen this issue several times on ford trucks, and it is usually a leaking intake plenum gasket.

I hope thios helps you, and I wish you luck on your repair.

Posted on May 10, 2009


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