I have a 1996 7.3 with 125K miles. I only drive it on weekends and put about 5K miiles per yeasr. I try to keep up with the regular maintenance. I year or so ago I had all of the glow plugs changed, due to hard starting in cooler weather. I do try to use fuel additive due to not going through alot of fuel and also keep a clean fuel & air filter. On occasion, I do notice a rough idle, but it seems to come & go and sometimes appears when the engine is cold, and sometimes when I've been driving for a while. While this is a vague issues, are there any obvious past issues with these engines, to check first?

 

I'd try a fuel system clean. Dump the fuel filter, refill with atf or dieselcleen, run for 30 seconds, shut off and let sit overnight.

 

I will give that I try, thank you. Maybe I was overthinking, like some type of sensor or bad injector, but I guess that this is a great starting point.

 

A small fuel leak will produce a rough idle. Even the smallest leak will suck a little air into the system and produce a rough idle. Not changing your oil in these trucks will make them idle rough. The motor oil is used as hydraulic fluid in the HEUI system. This causes the motor oil to become aerated after a few thousand miles and doesnt work as the hydraulic fluid very well.

 

Not that i have any personal experience with diesel motors, but my hunting buddy always plugs in his tractors and combines to keep the oil and coolant warm in cold weather.

 

Thank you, Bashby. That seemed to make a difference, and seems to have a little more power. The filter and bowl was dirty. I havent driven it alot, but so far so good. I appreciate your suggestion!!!!!!!!!!!

 

The fuel bowls will collect gunk in the bottom after time. Its hard to clean it out without damaging the fuel heater, but , it can be done.