buddy of mine has a 04 6.0 and he'll be driving down the road and it will just redline on the tach. but the mph won't go up with the revs... so this has happend to him 3-4times and he's sent it in and they can't find what's wrong with it.. and it doesn't help when they test drive it, it won't do it? so anyone have any ideas? it also doesn't help that i just talked him into ford... he was pretty much a die hard chev. guy

 

The dealership can install a "flight recorder" to your friend's truck.
It has a button on it that you push when the concern happens.
The dealer can then look at the recordings and determine the concern.
A lot of techs are scared of the 6.0 and would rather not work on them.

 

Reminds me of when I lived in the UK and had a 1986 Ford Sierra 2.3l Diesel, took it to the dealer and they sent me to a marine engine specialist 100 miles away!!

I presume International truck dealers may be better with the 6.0 engine and any probs it may have ?

Rich.

 

Has this truck been re flashed lately? It might need a re flash to cure the problem. I would not go to IH. I am not knocking the IH mechanics, it just that Ford has so much proprietary stuff that IH can't diagnose them sometimes.

 

No you can't take the truck to Navistar for warranty work. The engine may be made by it, but Navistar does nothing in the way of warranty work with it. Ford is the only one that can perform any warranty work on the truck no matter what the symptom. Reason being is that Navistar doesn't want to have to deal with warranty repairs when Ford is capable (usually) of doing it. Long story short, you can take it to Navistar but you will have to pay for the repairs. I have talked with local Navistar dealers and was told this as well as from a few friends who are techs at dealers across the country.

 

Sounds like the transmission is finding a false Neutral (a.k.a., slipping) while the truck is being driven. Doesn't sound like an engine issue.

 

but if the tranny was slipping wouldn't you be able to feel it and the mph go down also??? i know i had a 95 that slipped and you could feel that?

 

If I'm interpreting your first post correctly, the engine is racing and the tach is hitting redline without a corresponding increase in vehicle speed. The fact that the speed is not increasing in line with the engine rpm usually means some type of slippage. It's possible that if the slippage is very bad that the truck will slow down, but if it's less severe, then the truck merely will not pick up speed.

Tough to diagnose through a modem, but it doesn't sound like an engine fault.