300 i6 engine noise help

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Feb 9, 2009 | 09:23 PM

123FORD

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Joined: Jan 2009

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300 i6 engine noise help

Hello again,

I've been poking around and sticking my ear to different parts for months trying to figure out what this noise is in the engine bay.

I would describe it as a hollow monotone hum that goes in and out every few seconds as the motor idles. Its the most noticeable sound when the hood is open.

My mechanic first noticed it when the truck was in for radius rod bushing replacement, he stick his stethoscope to different accessories for a minute or two but couldn't put his finger on it and got back to the business at hand.

My first uneducated thoughts were it was an exhaust leak or some sort of loose bearing in the fan.

Any help would be great.

Thanks

Feb 9, 2009 | 09:28 PM

TEGIII

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Joined: Jun 2008

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From: PENNSBURG,PA.

Does it have that funky fan that looks like a can on the passengers side by the airbox?? If it does try unplugging it.

Feb 9, 2009 | 09:55 PM

123FORD

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I went out there again and farted around. The coffee can looking thing has two rubber hoses connected to it and everything looked fine and dandy. I didn't want to go pulling hoses that I didnt know anything about. The sound didn't seem to be coming from there either..

Also forgot to mention, its a 95 f150 with a standard transmission.

Feb 9, 2009 | 10:05 PM

TEGIII

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Joined: Jun 2008

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From: PENNSBURG,PA.

I am sorry..had a few that made some really funky noises.

Feb 9, 2009 | 10:35 PM

Crappie Buster

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Joined: Oct 2008

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Yeah my truck (95 with I-6) has made a humming noise for years, but I've always thought it was pretty normal. It may not be the same noise your talking about though. My dad's 94 with the I-6 has always did it to my knowledge. He's got 240,000 on it and still counting. Hope someone can help you with your problem.

Feb 9, 2009 | 10:35 PM

F150xlt

Posting Guru

Joined: Jan 2002

Posts: 1,346

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From: Baltimore

Remove the serpentine belt and that will eliminate the alternator, water pump, air pump, AC compressor, Cooling Fan, idler puller/belt tensioner and power steering pump.

*****Note: With the belt off the water pump is disabled. *******

Feb 9, 2009 | 11:16 PM

ford2go

Cargo Master

Joined: Apr 2003

Posts: 3,476

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From: Frequently frozen MN

IIRC there's some kind of air circulation system. I had one on an 89 I6 that would run at times. There's a fan and some pipes that snaked around the engine. I think it sometimes ran right after the engine was shut down.

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Feb 10, 2009 | 07:00 AM

BigSix1

More Turbo

Joined: Sep 2003

Posts: 630

Likes: 4

From: Northeast

Quote:

Originally Posted by ford2go

123Ford,

You were looking at the "coffee can" vapor canistor, but these guys (ford2go and TEGIII) are talking about the fan which runs (on my truck) only rarely, when it is heat-soaked, after it's been run hard and shut down. I believe it cools the fuel rail, but I can't remember for sure, if I ever knew. As was stated, unplug that when you hear the noise, and see if it abates.

And get a $15. stethascope yourself--I LOVE mine and it's very handy to have--you'll find it if you 'scope it enough!

Good luck!