Fix for a leaky FDC?

[Seth_O]

I have a leaky FDC (I assume: truck's making oil and I found diesel on the backside of the shut-off valve.) I thought I read a thread at some point from someone who fixed their leaking FDC, but I cannot get search to find the thread for me.

I know it's easier to bypass it, and it's not required to run the truck - but if a fix is possible I would prefer to fix it. Can anyone share with me a thread where they fixed their leaking FDC? Or a lead on a good FDC

 

[doghead]

Fuel inside the shut off housing, sounds more like a hydraulic head o ring leak or HH shaft leak, or boost pump leak.

With the cover off and the in tank pump on, can you see fuel dripping? Use a mirror.


You can also lift the FDC out of the housing and inspect for leakage, to positively identify if it is leaking.

I know of no reason, not to bypass the fdc.

 

[Seth_O]

Thanks DH. I wanted to keep the FDC in the loop because I tend to run A LOT of different fuels in mine - my understanding from my reading is that the FDC ensures a consistent power output amongst the different fuels.

Tks for the tip on the HH - I will check that out as soon as the weather allows me outside - tomorrow hopefully.

If I understand your post right, with the in-tank pump running (engine off) if my HH o-rings are bad I would have fuel dripping/visible behind the cut-off cover?

 

[doghead]

Yes, thats correct. Not guaranteed, but most likely.

As for the FDC, You really won't notice the power difference between fuels.

 

[Floridianson]

and if you do push harder on the right foot.

 

[gimpyrobb]

I have a spare FDC if you decide you need one.

 

[Jakob]

I have the illustration and thread about bypassing the FDC, but I couldn't find a good description of what's needed. Can anyone put together a parts list, if anything, is needed? If nothing is needed, I'll get to is ASAP. I know mine is leaking internally because on the oil change, it smelled of diesel fuel.

 

[Seth_O]

I have a spare FDC if you decide you need one.

Cheers Gimp - I'm going to check my HH monday per DH's tip to see if that's where my leak is. If it's the FDC I will be looking for a replacement and will happily take it off your hands.

 

[gimpyrobb]

I have the illustration and thread about bypassing the FDC, but I couldn't find a good description of what's needed. Can anyone put together a parts list, if anything, is needed? If nothing is needed, I'll get to is ASAP. I know mine is leaking internally because on the oil change, it smelled of diesel fuel.

Take the fuel line from the filters off the FDC.

Take the fuel line from the FDC to the Hydraulic head off and put it to the now open port on the FDC.

Run fuel line from filters to hydraulic head.

Done.

 

[Jakob]

Take the fuel line from the filters off the FDC.

Take the fuel line from the FDC to the Hydraulic head off and put it to the now open port on the FDC.

Run fuel line from filters to hydraulic head.

Done.

I have the diagram from the forums and seeing it done on that truck we scrapped helped visualize it as well.

 

[Seth_O]

Fuel inside the shut off housing, sounds more like a hydraulic head o ring leak or HH shaft leak, or boost pump leak.

Bingo. I popped the cutoff cover off today and found a pool of fuel inside it. I turned on the in-tank pump and almost instantly had fuel dripping from the HH. At a minimum from the O ring where the accelerator shaft goes in the side of the HH, and possibly from the internal O rings as well.

Thanks again DH.

FDC may be bad as well, but I'm going to tackle this issue first and see where it leaves me.

 

[gimpyrobb]

2.484x.139 and 2.109x.139 for the Orings the HH sits on. Not sure of the Oring size for that little shaft that goes in the side.

 

[Seth_O]

Cheers Gimp, headed to Napa today to see if they have them in stock. Hopefully this resolves the issue - if not I'll PM you re: your extra FDC.

 

[Seth_O]

I did a little research and found that there are industry standard sizes for o-rings, typically 3 digit codes. Not sure who everyone is using for a supplier but I ended up going here: www.applerubber.com. After Napa failed miserably, it turns out if you set up a free account with applerubber they will send you free samples (up to 6) so it was perfect for my needs.

Hydraulic Head o-ring sizes:

Large O-Ring: 2.484 x .139 = -230 or 230 (depending on which standard)
Small O-ring: 2.109 x .139 = -227 or 227 (depending on which standard)
Actuator O-Ring: .426 x .070 = -013 or 013 (depending on which standard)

For use with diesel or gasoline or oil, you want Buna N Nitrile (according to a couple of different websites I read through.)

Hopefully this helps some folks out, this seems to be a not uncommon issue. I'll finalize this thread when I get the samples and let folks know if/how well it worked out.

 

[silverstate55]

The FDC was already bypassed (done by Tooele Depot in Utah) in my truck, and I was thinking about putting in new O-rings & re-sealing everything before I reconnect it. I plan on running 90% filtered WMO/UMO & 10% diesel....

But what I am to understand is that even with that heavy of a concentration of oil as fuel, I don't need to run it through the FDC? I've read through just about every FDC thread I could find using the Search function, but the majority of them have to do with replacing O-rings or bypassing them altogether.

If I don't need to reconnect the FDC to run filtered motor oil, that would certainly be welcome news!

 

[Seth_O]

The o-rings I mentioned are in the hydraulic head, not in the FDC. FDC does not affect your ability to run alternative fuels in the deuce. With your FDC bypassed you are still able to run the same variety of fuels you could run pre-bypass.

 

[gimpyrobb]

I have those numbers on my Oring bags, I just thought they were a reference from my supplier, good to know. They do have V95-75 after the numbers, think that means Viton?

 

[Seth_O]

The 2 digit number (usually 40-90) is a measure of hardness. 'Standard' for these is 70, bigger numbers mean harder compound. They run in increments of 5. Not sure on the V, viton is a good guess.

 

[eagle4g63]

The FDC was already bypassed (done by Tooele Depot in Utah) in my truck, and I was thinking about putting in new O-rings & re-sealing everything before I reconnect it. I plan on running 90% filtered WMO/UMO & 10% diesel....

But what I am to understand is that even with that heavy of a concentration of oil as fuel, I don't need to run it through the FDC? I've read through just about every FDC thread I could find using the Search function, but the majority of them have to do with replacing O-rings or bypassing them altogether.

If I don't need to reconnect the FDC to run filtered motor oil, that would certainly be welcome news!

I can tell you that with MY truck the FDC worked against me when I started to use WMO and I had to bypass it to get a semi-normal pedal. So if I were you I would leave the truck the way it is if you want to use motor oil for fuel!!

 

[andytk5]

Great info guys. I am looking into this as I also have fuel going into my oil from somewhere. My FDC was already bypassed so another member "Horst" suggested the HH o-ring as another place to check.

Seth - Looing forward to your results