Replace IP or bypass FDC?

[rdixiemiller]

As you have read, my deuce is making its own oil, really thin and smells of diesel!
Could be the FDC leaking, the hydraulic head, or the fuel pump. It has made between 4 and 5" on the dipstick in 200 miles or so. Not counting what it blew out and coated the side of the truck with.

I have a spare IP, but it is a pain to change one out.

I am seriously considered just bypassing the FDC , changing the oil, and trying that first. I risk 6 gallons of oil if I am wrong.

I don't know what the frequency of failures is with the rest of the pump, I do know the military was bypassing all of the FDC's because of leakage concerns.

What is the group opinion?

 

[Recovry4x4]

Thats what i would do. IP swaps are a pain. The oil won't be totally wasted, filter it and burn it.

 

[cbvet]

I really like having the FDC working.
I burn all kinds of fuels, including gasoline mixed with filtered waste oil, gasoline/diesel mix, leftover chainsaw fuel, outboard motor fuel, or straight diesel.
I believe I'd fix it.
But then again, I have no idea how tough a job it would be.
Eric
CBVET

 

[Stretch44875]

I'm with cbvet, burn anything I can to save on fuel cost. But if you just run diesel, why not bypass. Any way to pressure check an ip that's out of the truck for leaks?

Dennis

 

[rdixiemiller]

Don't know if you can really pressure test it, you would have to hook it up to a set of injectors and turn the pump with a motor, all the while supplying it with lubricating oil. I run diesel mixed with some WMO, so I don't really need the FDC. I don't run gasoline, so no issue.
IP swaps are a pain. You really need a helper and pull the drivers fender and radiator out.

 

[clinto]

Bypass that sucker. Must have been a significant (read: common) enough problem that the military chose to give up the the FDC's-note how many trucks have their FDC's bypassed.

 

[cranetruck]

Robert, if you suspect the FDC, just replace it. It is an easy job, I have had mine off for modifications.

If the FDC leaks, it would effect its calibration.

I'd like to know the real reason for bypassing them, if they are bypassed there will be a slight increase in fuel delivery for any fuel used, for example.

 

[WillWagner]

There is a dye you can put in the fuel. Go get some and a black light, put the dye in the tank, run it a bit, then pull the FDC and look to see if it's glowing yellow on the oil side, if not, move to the next part. Diesel and bearings don't mix, it will ruin a set of bearings right now. Try not to run it too much like this. The dye is the same for oil or fuel. I have some here if you decide you want to try it, or Cummis sells it, p/n, 3376891. Good luck, keep us posted

Oh yeah, 1 of those little bottles only dyes 10 gal., so, if you have 25-30 gals in the tank, you'll need 3 bottles.

 

[cranetruck]

The black rectangle shows the shaft where a leak would occur if at all. The shaft/bore is the only connection between the fuel and the IP governor housing.

 

[jwaller]

replace the FDC and see if it still does the same problem. filter your old oil and burn it.

 

[FreightTrain]

yea,I say repair it to keep the multi part working.You never know when you will need to burn something other than oil.Look what happened right after Katrina!One storm and all hell broke loose.Just think what would happen if it had hit the refineries in Texas or worst,had a combo hit where the west coast has a major Earthquake and even a weak to moderate tropical system makes a dead bullseye on the refineries.Kat showed it didn't take much to totally screw us up....

 

[67Beast]

Mine seams to do the same thing except mine only does it when I travel at highway speeds (55) for extended times (hour or more). Not very much, just a couple of quarts over. But enough that it come out a breather/vent line at the bellhousing. anyone have a clue. FDC? and if so is there a seal on the shaft and what would the part # be for it?

 

[Michael]

As you have read, my deuce is making its own oil, really thin and smells of diesel!
Could be the FDC leaking, the hydraulic head, or the fuel pump. It has made between 4 and 5" on the dipstick in 200 miles or so. Not counting what it blew out and coated the side of the truck with.

I have a spare IP, but it is a pain to change one out.

I am seriously considered just bypassing the FDC , changing the oil, and trying that first. I risk 6 gallons of oil if I am wrong.

I don't know what the frequency of failures is with the rest of the pump, I do know the military was bypassing all of the FDC's because of leakage concerns.

What is the group opinion?

Did you ever find your leak? Mine is doing the same thing.

 

[avengeusa]

the fdc can be bypassed without stopping the ability to run different fuels

 

[cranetruck]

Did you ever find your leak? Mine is doing the same thing.

Out of curiosity, how is your fuel tank, any rust?
One cause of fuel in the crankcase oil is a leaking FDC piston rod. The metal to metal seal can be marred by tiny rust particles and fuel will leak directly into the IP and mix with the oil.

So, bypass the FDC, change oil and go from there.

 

[bugei]

just a word of caution. if you thin your oil out you will quickly loose the lubrication and end up with a siezed motor. i had a small hole in a piston on a duece i recovered and in less than 200 miles got to meet mr tow truck.

 

[Michael]

Tank is clean. I did pour 5 gal of old gas mixed with 2 gal of NOS motor oil then diluted with a fresh fill of diesel just before I started having trouble.

Normally I only use diesel.

 

[yellobronc]

the fdc can be bypassed without stopping the ability to run different fuels

I knew this answer was coming. Suprised it is so far down the tread. Get a Pyro, dump the FDC.

 

[avengeusa]

I knew this answer was coming. Suprised it is so far down the tread. Get a Pyro, dump the FDC.

mine is bypassed, and runs on oil, lol, and gasoline just fine

 

[Chevytruck]

Just bypass the sucker and begone with it!

you don't need the FDC to keep the engine multifuel, all the fdc does is compensate for the density of the fuel...
the FDC is bypassed on most of the vehicles already... one of the reasons it was probably phased out of the military is that it leaks easily...

crazy misguided rant over...