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Old 05-27-2011
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Thunking from front end on startup

hey everyone,

I did a search to see if any threads already mentioned this, and i didnt see any. Apologies in advance if i missed them and am reposting a common issue...

My truck is next to brand new, 2000 km on it, bought her new. Every now and then when i start it up, sometimes from cold, sometimes not, there will be a hard sounding thunk from the front end, sounding like its coming from the passenger side. It almost sounds like somebody is smacking the outside of the truck, either that or the belt is unajmming a stuck pulley wheel somewhere. Ive looked under the hood while my wife started it and cant see anything obvious, and of course when im looking under there it doesnt do it.

Sometimes it will do it from a start when im at a red light. But no obvious decline in performance or anything like that is noticed.

Anyone else experiencing this?
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Old 05-27-2011
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Your truck is new. You have a 3 year warranty. They will diagnose it and repair it
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Old 06-19-2011
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Gunman, have you looked into this?
my 2007 does the exact same thing. typically its only on the first start of the day or a start after sitting for a long time. its a "thud" that sounds like its coming from upfront somewhere, or near the hump. Its timing would be that of the starter solenoid disengaging. but ive never heard it while at traffic lights (like yours)

when my ac compressor kicks on it makes a similar thud noise. the truck has been great so im not too worried and i have another 50k left on my warranty so i will have it looked at some point but dont feel like having to leave the truck with them overnight so they'll hear it.
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Old 06-19-2011
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Same problem with my 06. May go several weeks at the time without it. Sounds like maybe the transmission????
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Old 06-19-2011
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I don't know how this could point to tranny if it's occurring right at start up though?
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Old 06-19-2011
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Unless it has something to do with the torque converter or clutches engaging. Was going to carry mine to the dealership while it was under warranty, but it didn't always do it, so I figured it was a waste of time. Mine usually does it about 3-5 seconds after startup, and sounds like its coming from the transmission area.
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Old 06-19-2011
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the thunk i hear 3-5 seconds after start up i believe is my AC Compressor kicking on, its a little quieter of a thud... see if your truck still does it with the AC off.

there is one that is much more prominent that i hear just as the starter is disengaging

like yours it only does it, once a day on the first cold start. so i figured leaving it over night at the dealer is just going to be a PITA. and the tech might even report "Could not replicate"
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Old 06-20-2011
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i made a recording of the thud... 4 seconds...
its right at the very end, im surprised how audible it was on the recording... you'll hear the starter then just as the starter is finishing the distinct 'thump'...
link here if the embedding doest work...
http://www.youtube.com/watch?v=D5kCMpUHlj8


Last edited by B737; 06-20-2011 at 10:53 PM.
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Old 08-31-2011
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My '08 does this on occasion as well... Only when Cold...
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Old 08-31-2011
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Hey guys,
I'm not sure if ford incorporates this in their engines or not; but I know from being a motorcycle mechanic, and many manufactures use this, there is a small mechanism in the valve train that opens an exhaust valve ever so slightly so the starter doesn't have to overwork itself with the compression stroke, and it sounds exactly like that.
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Old 09-01-2011
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i almost feel like its a solenoid or something thumping against the cab floor, its just a 'low' noise. i find some relief that others hear it. but no clue what it could be....

Last edited by B737; 09-02-2011 at 07:44 PM.
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Old 09-02-2011
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Did you ever carry it to the dealer for a diagnosis? I've noticed mine hasn't done this lately...
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Old 09-10-2011
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I have a loose shifter that i want the dealer to take a look at but im waiting for other things to break before i bring it to them for warranty work... so it might be a while.
but oddly enough...
two weeks ago the truck hit 50,000 miles
i changed the coolant, transmission filter and fluid, transfer case fluid and i put on a new serpentine belt.
it might be a coincidence, but i have not heard the thud since..
odd right??

the only thing i can think of is it might have been something related to the belt...
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Old 09-10-2011
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This happens to my 07 when I leave for work in the morning. Not every morning, but often. Your not the only one. Im thinking its the belt. I have to replace my belt next weekend. If the thump stops, that would answer the problem. Damn it sounds just wrong you know?!

Last edited by Timberwolf; 09-10-2011 at 07:06 PM.
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