I have an interesting problem, 2004 F150 XLT 5.4, 128K, when it is in 2WD drive and you accelerate at any speed it sounds like marbles are in it when you are under load, centered mostly to the right/passenger side, when I take my foot off the accelerator and let it coast the sound goes away, when it is 4WD it sounds fine, reverse it is still present but you have to get up to about 20mph before you hear it, dealer said it is spark knock and cam phasers, transmission shop said spark knock, but no one can explain why it doesn't do it in 4WD, the dealer wants a fair amount to fix it, and I don't have an issue with that, but before I do I want to be sure that will correct the issue and of course they can't promise that, anyone else have the same issue? I think it is the transfer case due to when it is engaged in 4WD it goes away, but then again I'm not a mechanic. Ideas? Power and MPG are fine.

Also, any one know a good independent Ford mechanic in the Metro Detroit area?

Thanks,
Tim

 

Sounds more like IWE issues to me.

 

GLC, thanks for the suggestion, on the driver side iwe the vacuum hose was off, reconnected and it works great. I had my upper ball joints replaced about two weeks ago and I gather the tire shop did the passenger side tube, but not the driver. I really appreciate it.
Thanks again,
Tim

 

So that hose made the sound go away? My 05 with 144k sometimes has a rattle kind if sound when it's in the mid upper rpms. It's not evert time I go wot. I was thinking spark knock...or the timing chain rattling. Also to not my 4 hi is out...I think because I have the old non covered iwe. So I can't go fast in 4wd to see if it does it there.

 

Yep, the vacuum hose was just disconnected, putting that back on and the grinding/marble sound went completely away. I would look at these videos:

Guy who explains it.

http://www.youtube.com/watch?v=148Eal6lBX8

Ford presentation about it

http://www.youtube.com/watch?v=8E3eJdy3RpY

And make sure your vacuum pressure is good to go, testing it was super simple, perhaps you just have a minor leak and some new tube will take care of it.

-Tim