How does PEX hold up in diesel fuel?

[jim x 3]

I need to fix/replace the fuel filler to my rear tank.

I have searched and seen info on the fuel filler mod, but I think I'd like to stick with the stock pipe-in-pipe configuration so the tank connection(s) don't need to be changed. My inner pipe (which appears to be for fuel into tank) needs to be replaced. It is 7/8 ID, about the same as 1" PEX (cross linked polyethylene) plumbing pipe. Does anyone have info regarding fuel oil interaction with PEX?

Thanks and regards,

 

[punkmechanic]

I just removed the inner pipe altogether and then remounted the outer hose back up. No changes to connections at all. The only "modification" I did was to pull the tank vent and bore it out so its an open hole, then run the tube above the fill cap level so it wont leak.

Works great and I could just about fill my tank with a firehose.

To answer your question diesel eats all kinda stuff, best bet is to take a small piece of that and put it in a cup of diesel fuel in the garage. let it sit overnight or a couple days and see if it gets soft or hard or dissolves. etc.

punk

 

[smolkin]

Although I haven't tried it, I've heard it holds up to diesel and WVO well, after all it is polyethylene, the same stuff used for alot of fuel tanks.

 

[G. Mann]

I did this trick and it worked great.
Removed the vent valve at the top of the tanks and replaced them with vent valves from a 97 truck. [stealership item.. sorry, don't know the part number]... the 97 vent valve / rollover valve uses a 1/2 inch vent line which totally cured the "puke fuel on fill trick" that I was having with the old system.

Simple fix with the bed off. the new valves popped right into the same tank holes with new rubbers, added 1/2 inch rubber hose [heater hose] and now the tanks vent and fill.

 

[typ4]

What has happened on a lot of the trucks, like mine, is the hose sags then pinches off the flow, no amount of venting will fix that. I took mine off, bored the vents and it fills awesome now.

 

[NJKen]

Im not sure about PEX but I know the Sinflex (big truck plastic airline) holds up to almost anything incuding diesel. I have used it in a pinch before. The fittings for it seem to hold up well also.
Ken

 

[jim_22]

Pex is fine, I have had one on my diesel Mercedes for 3+ years.

 

[Jake_IN]

I find I don't like to get diesel fuel on my pex. Makes them smell funny and then the ladies complain.

 

[NJKen]

I find I don't like to get diesel fuel on my pex. Makes them smell funny and then the ladies complain.

LMAO!

Ken

 

[ulmapache]

Ooohhh Pancho....Ohhh Cisco!!

 

[Oledirtypearl86]

Pretty sure the fass fuel systems use pex in the tank

 

[nelstomlinson]

I did this trick and it worked great.
Removed the vent valve at the top of the tanks and replaced them with vent valves from a 97 truck. [stealership item.. sorry, don't know the part number]... the 97 vent valve / rollover valve uses a 1/2 inch vent line which totally cured the "puke fuel on fill trick" that I was having with the old system.

Was it like this little ******? DORMAN 911060
https://www.rockauto.com/en/catalog...1127090,fuel+&+air,fuel+tank+vent+valve,11246

 

[G. Mann]

Can't tell from the picture. If the vent line barb fitting is 1/2 inch... Bob's yer Unkle..
If it's smaller.... it will puke fuel...when you fill..

The 97 roll over valve in much larger, compared to the OBS size, which is, if I recall 3/8's and doesn't vent enough air when you are pumping fuel, so pressure builds up on tank and pukes out the fuel in the fill hose + the fill nozzle flow...

 

[aggiediesel01]

Can't tell from the picture. If the vent line barb fitting is 1/2 inch... Bob's yer Unkle..
If it's smaller.... it will puke fuel...when you fill..

The 97 roll over valve in much larger, compared to the OBS size, which is, if I recall 3/8's and doesn't vent enough air when you are pumping fuel, so pressure builds up on tank and pukes out the fuel in the fill hose + the fill nozzle flow...

How long ago did you do this? The only larger diameter rollover valves I remember were for Cab and Chassis trucks they are much different because their fillers don't use the hose in hose design. Last time I tried to get some they were out nationwide. You can still find them at wrecking yards in cab and chassis trucks but they are brittle by now so be careful pulling them out. They look something like this:

View media item 618View media item 620
and require this gasket:
View media item 621View media item 619

 

[G. Mann]

That is the roll over valve I used, both tanks, which cured the problem.
The grommet that fits the tank is the same size as the small hose roll over valve, so it is a "direct fit" into the tank. I used the old grommets, didn't bother changing them out.

All I can say is, "It worked for me".. "Should work for you". The truck I installed them on would NOT fill at the pump without puking back several gallons of fuel during the attempt to fill either tank, EVERY time...
Once I changed to the large tube roll over valves... full flow at the nozzle and never a single puke.
You need to swap the fill necks to the style that has the 1/2 inch hose above the fill nozzle insert point.. so you pump fuel below where the air is flowing out the top of the tank..
Pick and Pull is your friend there.. Ford Stealership wants big bucks for fill pipes, as I recall.

I did this so long ago, I had forgotten about using the filler necks... sorry