My wife is out on the road with what i though was the dependable truck.

While she isn't mechanically inclined, she described the following:

I was driving up a hill with cruise on 65. all of a sudden the rpms jumped to 3000 and the speed dropped from 65 to 30 mph.

they pulled over and called me. I talked them through checking all the fluids and pulling codes off odometer.

-no codes
-oil ad "add" level

everything else seems fine.

after filling it up from half tank to full tank while stopped they cranked it and left. slipped again when she shifted to second..... and has ran fine since then-no slipping.

never smelled a burning clutch.

stopped by mechanic who said "you have no codes and you should have smelled clutch if it was problem" and "sounds like bad fuel, go buy some diesel clean"

she is positive she has only put diesel in it.

Truck: 2000 24 valve 5 speed 1 ton pulling horse trailer - about (7k lbs) no signs of clutch slipping in the 8k miles that I have owned the truck (145k total miles probably due to go out)

my question: can bad fuel cause high rpm's? i think bad fuel would cause low rpm's. Also, i cant understand how the clutch was not slipping with increase in rpms and decrease in speed.

 

the truck in question is not the truck in my sig.

2000 1 ton 5 speed, no mods, kinda weak has high gear ratio. Unsure on history before 137k miles when i bought it. no wrench turning or problems until today (145k miles)

 

There is no physical way that bad fuel could cause the engine to rev faster & the vehicle to be slower. That statement makes almost as much sense as saying 'bad fuel caused the headlights to stay on'. I would put my money on slipping clutch, its the only thing it could be short of a transmission problem (spinning 5th gear?)

 

What about the clutch pedal hanging up?

Does the pedal movement seem normal?

 

Jeepstang- I thought the same thing, but didnt wanna make an edit of myself over the phone with that guy if I was wrong.

fox- she didnt mention clutch pedal issues, she is on road home with no issues lately. and 5th gear is common on the older transmissions, not mine....I think.
also it happened when she put it in second as well.

I will check that when she gets in.

I told her to try to make it slip again on the road home goin up a hill hammer on it.
- no slipping no problems just the weak truck not pulling that great.

thanks for the brainstorming guys. this may be a tough one to diagnose if I cant re-create the issue.

 

Perhaps You should read the TSB. The OP's symptoms are no where near those of a loose/failed 5th gear nut.

 

I can't recreate it. No clutch slipping no noises. Evrything seems fine. Not sure what to do.

 

sure sounds like a clutch slipping issue. could do a apps reset as well.

 

My dad has an 03 Superduty, V-10 with the 6 speed. 17,000 miles on it. He was pulling a tractor one day, and out of the blue, the same thing happened to him. It didn't repeat itself for a while- it was intermittent. Turns out, it was the clutch- there were broken fingers on it, and it wouldn't always hold tight.
Dollars to donuts that you have a clutch issue. It could slip intermittently, and not make a huge amount of smoke or odor.

 

This is no longer an emergency... But still an interesting discussion, can we bump it over to second gen. Drivetrain? Issue still unresolved and no symptoms

 

With that mileage and no knowledge of what was done previously, I would pull the clutch just to check it.

 

Maybe i have slipped into the "if it aint broke dont fix it" mode. But pulling the tranny to inspect the clutch is a huge hassle. And once I got it apart I would want to put a new clutch in there to avoid doing this all over again later. $1000-$1500 later I MAY have fixed the problem

So i guess I'm sayin, anymore ideas other than clutch to check first? anyway to inspect the clutch without pulling tranny?

I have tried to break the clutch loose with the trailer goin up a decent hill and cant. Of course this stock engine is one of the weakest I have driven with the high gear ratio. I didnt realize how much power my other truck really has until i drove this one.