was driving to work today and there was a rumbling from the engine above 4500 rpms.decided to take to the dealer after work.After only 7 miles it had worsened to the point that it was making the whole truck shake even idling.Developed to a knock instead of a drone.
what do you think.main bearing?connecting rod.broken valve?

2003 ,4.7 with only 85000 miles on it

parked and towed once it got badrebuild or new truck?

woodchip

 

I will move this to the 3rd gen section for you, get you some opinions/help.

 

thanks.
timing chain?

 

IDK but I would assume something internal from the way you described. It could be anything you mentioned. Let us know what the shop finds out.

 

I was originally going to say U-joints, because mine just did that, but you say it is knocking even when idling (and I assume not moving).

If it's not that, then timing is probably off, assuming you haven't thrown a rod or something. CPS or timing chain would be a good place to start.

Greg

 

I just remembered 4.7's have known issues with throwing a rocker arm so if it did that then it would be running on one (or more) less cylinders so that could cause it also

 

Did the dealer diagnose the problem yet? Were you planning on having them find the problem and then you work on it or were you just curious what could be the problem?

I dont understand what you are saying here?????

 

my 4.7 blow up at 80,000 air filter not in box right fried the pistons took it apart and the timing chain was loose as hell, only had the truck for 3,000 miles bought it from my dad and he never drove it hard it cost me 4,000 dallors to rebuild and bore, then the tranny went out 5,000 miles later talk about bad luck

 

dealer replaced the water pump and then did a tune up.seemed fine but after 3 miles it started to overheat.they have now pulled the heads and looking for a cracked head or a blown gasket.the water pump impellor had dissinagrated originally.apparently i rev the engine too much.

 

I wonder if your harmonic damper took a dump on you... Its hard to say... Keep us posted.

SPEED SAFE, NICK