Alright, after purchasing the truck at 238,000 miles I've started out with some basic repairs to get the truck in decent driving shape. The only thing I've done to the motor is changed to Rotella, a belt and flush the green crap coolant out.

The truck starts and runs well even in the cold weather without being plugged in, with a minimal amount of blue smoke, after being started. The exhaust is always fairly clean for its age but does seem to have a slight 'haze' under load but not rolling coal or any thing. The motor always idles smooth after starting and only seems to have a rough idle after being under load for a long time (running down the highway with a camper for instance) where it will miss and buck and throw an engine code. I've had the truck in to check for a code but it never has a code when they go to read it. It might also be a good time to mention that I have a little oil in the valley.

Ok, right now the truck is getting a new transmission and a transfer case rebuild. So after the trauma of paying for that mess, it's looking like I'll be looking at the injection side of the motor. Guessing by the missing after being under load and the mileage of the truck (258,000 miles) and the hpop oil leak, I'm thinking a few worn injectors, possibly a lift pump and or hpop. I've not done any mods to the motor, there is no tuner or gauges of any type. Obviously there are a laundry list of mods to be made yet but I think that the first order of business is to determine the condition of the injection system. I've yet to get an oil sample done but It's on the list of things to do.

Where should I start trouble shooting? Any thoughts?

Thanks for all the input thus far!


Here my thread if you want a little more back ground on the truck.

https://www.ford-trucks.com/forums/1...ght=commercial

 

Any ideas?

 

You need to get the code read. If the CEL comes on, there is a code stored. The 7.3 is not an OBDII compliant motor, so don't believe all those scanners that say all vehicles 96 and up. You need a better scanner to pull the engine specific codes off these trucks since the engine was designed as a medium duty platform engine.

A good diesel shop, or a shop that works on bobtails or big trucks can probably scan it for you. Also consider calling your local school district and find out who works on their school bus engines. Odds are several of those had a 7.3 at one time so the mechanic will have the right equipment.

 

On mine it used to had rough idle after hot HARD drive. It was cheap supertech oil that was aerator air bubble which cause rpm bounce around 100 when sit in Park.

After switch to Shell T6 5w40 it gone but still had romp on cold start like 20oF. No more rough idle anymore expect it run quiet and smooth.

On cold engine when high idle kick mine look like train steam that was really bad. It was blue smoke. Everybody say bad injectors but problem is it miss for short time so I believe 1 or 2 bad injectors. But it not show bad injector on test when oil temp get up 100oF.


On oil in valley could be come from HPOP and fuel filter housing leak.

I would bring scanner to you if I can do. Possible weekend if it doesn't snow.

 

Oil in the valley could be leaking HPOP o-rings, turbo pedestal o-rings, ICP sensor, etc... any numbe rof things. Clean it real good and look again.

Check for codes. Might just be some loose UVCH connectors that need to be replaced or need the clips added, or the 50 cent mod done.

Rough running could also be a fuel starvation or oil aeration problem.