Mystery grinding noise after cold start

[dixonk]

It's the ac compressor. One way to test is to change the remote start settings to use the last setting and not auto. Then turn on the face vents, heat to max, and make sure a/c light is off and front defroster is off. Remote start it and the compressor should stay off and not make the sound. Also, the truck must be cold for the sound, explanation below.



I chased this for awhile and replaced the ac pulley, clutch, and clutch coil. I found that once the compressor sits for a long period of time it gets stubborn to turn and this sound is the first jolt of it turning. I didn't replace the compressor so I'm unsure if a new one will make the sound go away or not and if this sound is a sign of the compressor going bad. However, I remember reading somewhere that a Ford engineer said it's due to the compressor being the lowest part of the system and as it sits all the freon/oil drains down to it and makes it have more stress when it first turns over.

Interesting. I had a feeling it was compressor because of the timeframe when the grinding happens. Everything is already running as far as engine goes and then it grinds very briefly.


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[Caliraptor2lit]

So, if I only drive my truck around one a week, should I make sure to use the AC every time? Or not at all? Is one way better for longevity?

 

[Turk10mm]

Just so ya'll know, my 18 and another 18 in Houston are in the shop right now waiting on 4 replacement cam phasers for this. Its been 2 weeks. At least i'm riding around in a Lariat.

~1 second grinding noise at cold start only.

https://www.youtube.com/watch?v=iq6aUvB6fa0

 

[dixonk]

Just so ya'll know, my 18 and another 18 in Houston are in the shop right now waiting on 4 replacement cam phasers for this. Its been 2 weeks. At least i'm riding around in a Lariat.

~1 second grinding noise at cold start only.

https://www.youtube.com/watch?v=iq6aUvB6fa0

On mine the grinding noise would occur after that video is finished not right at startup.


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[LXCoupe]

Just so ya'll know, my 18 and another 18 in Houston are in the shop right now waiting on 4 replacement cam phasers for this. Its been 2 weeks. At least i'm riding around in a Lariat.

~1 second grinding noise at cold start only.

https://www.youtube.com/watch?v=iq6aUvB6fa0

The Gen1 sound is a little different, it's delayed. The sound is a a couple seconds after truck is running.

A video of mine is below.

Clunk is at 9 seconds. It’s not as loud as it usually is and I think this is due to it not being very warm today. Btw truck had been sitting for at least a week.

 

[dixonk]

The Gen1 sound is a little different, it's delayed. The sound is a a couple seconds after truck is running.

A video of mine is below.

Clunk is at 9 seconds. It’s not as loud as it usually is and I think this is due to it not being very warm today. Btw truck had been sitting for at least a week.

Mine comes on about the same time as yours does but it is a quick grind and then stops. Maybe a second or two but loud.


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[Swacer]

I had a grind the first time I turned the AC on this summer. Kinda took me by surprise. However, I can go a week or two now, and when the AC comes on, its quiet.

 

[Gary E]

Mine comes on about the same time as yours does but it is a quick grind and then stops. Maybe a second or two but loud.

Likewise with my 2014, 27,000 miles.

 

[Gary E]

A short video of the cold startup grinding noise. Sound is at 6 seconds in the 10 second video.

https://youtu.be/tCeO4Tr5XL8

 

[dixonk]

A short video of the cold startup grinding noise. Sound is at 6 seconds in the 10 second video.

https://youtu.be/tCeO4Tr5XL8

That is exactly the noise I have been trying to describe.