Jackhammer sound on startup

[Zeek]

Hi everyone, when I start my truck, I get a jackhammer like sound coming from up by the fan but there is no contact there. i am kind of thinking it could possibly be the A/C clutch but i am not 100% sure. Has anyone had something like this? Does anyone have insight?

[at0075]

It's prb your injectors sticking and it sounds like total crap. Mine sounds like a jack hammer every morning

[Zeek]

I definitely don't think it is the injectors, because it happens some of the time, and not all the time, also whether it is hot or cold won't tell me if it is going to happen. I stick my head in the engine bay and it sounds like straight metal on metal from the front of the truck. But i could be wrong and my ears can play tricks on me, 13 years of big guns, little guns and pistols and most of the time no hearing protection can do that to ya.

[justinmix]

If you listen thru the grill does it make a rattling metal sound? If so it's probably the fan clutch. I've had some trucks that do this and the fan clutch still works fine, but it should probably be replaced.

Try turning on the AC when you hear it doing this. If the noise goes away with the AC on suspect the AC compressor clutch, if it's still there then I'd bet money on the fan clutch.

[Zeek]

It does change a little when the A/C kicks in but that would most likely just be doing that because of the change in drag on the belt, I was originally thinking the A/C clutch but now that you say it, I am suspecting the fan clutch. Thanks.

[justinmix]

If you pop out the "Powerstroke" badge from the fan shroud you can peek down thru the shroud and see the fan clutch. Try taking a long screwdriver and pushing against the large washer on the end of the fan clutch. See if the noise changes when you do this. You can also try pulling on the fan clutch wiring and seeing if the noise changes. If it does at all then it's the fan clutch causing the noise.