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Wayne Crawford
Wayne Crawford, Shop Owner
Category: Ford
Satisfied Customers: 3904
Experience:  General Repair Shop Owner
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My 2004 Ford F150 has a whistling sound similar to what the

Customer Question

Customer: ***** ***** Jackson. My 2004 Ford F150 has a whistling sound similar to what the old smog pumps sounded like when they went bad. When the engine is cold, it is quiet, but starts to whistle within about 3 minutes (at an idle). And then when I shut the engine off, it continues for about 3 seconds. Just installed a brand new Ford crate motor. The sound seemed to be coming from either the torque converter or transmission pump, so I had the transmission rebuilt. Truck has 139000 miles on it and I acquired it with the bad motor. Removed the fan belt and the noise continued. Could it be coming from the EGR valve?
JA: Thanks. Can you give me any more details about your issue?
Customer: I tried to eliminate vacuum by removing the line at the intake manifold, but made no difference.
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Customer: Yes I need to take this truck on a trip Thursday the 7th. Any help would be appreciated.
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Submitted: 11 months ago.
Category: Ford
Expert:  Wayne Crawford replied 11 months ago.

Hello. My name is ***** ***** I will be helping you today.

Do you have an exhaust backpressure tester? Or a stethescope?

Usually when there is a whistling concern on one of these its either the heater core or a slightly restricted exhaust. I have never heard one making the noise after its turned off but I would just verify with a stethescope where the noise is coming from or check the backpressure and see if there is an exhaust restriction to start.

Customer: replied 11 months ago.
Already gutted the cats as they were plugged and causing a loss of power. Installed dummy o2 sensors. And it definitely makes a noise after shut down leading me to believe it was vacuum related
Expert:  Wayne Crawford replied 11 months ago.

Whats to say the muffler isnt clogged as well?

Customer: replied 11 months ago.
Good point . I was going to order a new cat back exhaust system but ran out of money. The power seems to be ok at this time
Expert:  Wayne Crawford replied 11 months ago.

I would double check it. Its the most common thing I hear on these making a whistling noise. If its restricted it will make a noise through the intake.. again I dont recall it ever making the noise after it was turned off but I wouldnt rule the exhaust out just based on that... nothing is still moving when the engine is off except for electrical stuff like the blower motor but those wouldnt turn off in just a few seconds.

Customer: replied 11 months ago.
Ok. I will disconnect the pipe between the cats and the muffler tomorrow . I will reply after trying this. Thanks. Also I'm putting it on a lift tomorrow and using a stethoscope .
Expert:  Wayne Crawford replied 11 months ago.

Sounds good. Let me know what you find. I will be standing by.

Customer: replied 11 months ago.
Just found the problem. The crankcase ventilation and purge valves were hooked up wrong
Expert:  Wayne Crawford replied 11 months ago.

Hmm. Glad to hear you got it worked out. Thats definitely a new one for me. It would have taken a while to get to that. LOL. Definitely a curve ball.

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