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A Mooing Car

This is a noise from a 2000 Ford Contour (2.5L) with 80,000 miles. Intermittent. Sometimes after the car is started, there’s a monotone noise, like a cow mooing. May last only 15-20 seconds.

What is my car trying to tell me?

It sounds like there might be a problem in the EVAP system.

This system stores fuel vapors in a carbon canister. When the engine is started, a canister purge control valve opens allowing this fuel vapor to drawn into the engine to be burned. Depending on how much fuel vapor is collected in the canister determines how long this purge valve remains open. I believe what you’re hearing is when the vacuum is applied to the canister from the engine to pull in the fuel vapors, either the canister is vibrating, or the purge valve diaphram is vibrating.


If this is an EVAP system problem like you believe, should the carbon cannister be replaced? Or might an adjustment of some kind be indicated?


The EVAP system on your vehicle is mounted on the gas tank. If the canister is loose in it’s mount, guess what kind of noise it can make?


I know your car is a Ford, but on BMW there was a “crankcase vent valve” mounted on the back of the intake manifold, when the diaphram on this valve ruptured it would moo like a cow.

It could also be a failing IAC (idle air control) valve. I know that on later revisions of Ford modular V8s they make a fog horn sound when they are going bad.

Your Mooing Car Is Trying To Tell You …
… that a mechanic will be “milking you” for a diagnosis and repair expense in the near future. Sorry, I couldn’t help it.

Additional information–the noise is definitely coming from the front. If the car has a clogged fuel filter, could this be generating the noise?

My 99 Contour SVT does/did the same thing. I think it comes from the air intake box. Check out Posts on the Contour club web site. I installed a cold air intake and the noise seems to have gone away, but I don’t drive it enough to be sure. If it is the same noise mine has,it will not hurt anything.
Good luck,

This is (with high probability) caused by the IAC; this is a common problem with this model. It will get worse over time, causing starting/idle problems. A replacement part should cost you about $60-$80 and takes about 5 minutes to install (2 nuts, one electrical connector, be sure to replace the gasket; the new part should come with a new gasket). The part is on the upper-back side of the engine; once you have the new part (so that you know what it looks like) you won’t have any trouble finding it.

If you search for “ford Contour” and “moosing” (i.e. making a noise like a moose) you will get all kinds of good info about this.