Rubber components in early 6.5 fuel systems?

[KingNuzz]

Want to keep an eye on and upgrade any "rubber" components that could be degraded by biodiesel use. My question to those of you with experience, is what parts to watch for. Anything else or different from what's listed below?

- Flexible fuel lines from area of firewall to engine
- Return lines at injectors
- DB2 Injection pump seals or ?
- Other?

Does anyone know what materials these different parts are made of? Viton does best with biodiesel, natural rubber doesnt't.

[More Power]

Most internal fuel injection pump seals and o-rings have been manufactured using Viton since 1993, occurring sometime after the introduction of low sulfur diesel fuel in California.

You could test the remaining external flexible fuel tubing used on the 6.5 by placing a sample in a sealed container with the bio-fuel. Look for swelling/softening or hardening.

MP

[tom.mcinerney]

On my '95 all the OEM fuel lines were fluoroelastomer-lined(like viton, or viton; replacement SAE J30 R9). Except for the injector return lines- no idea what they were. Suggest upgrade the large oring on the fuel conditioner/heater , don't know its composition.

[cruzer]

What are you all using for replacement fuel line?
Regular fuel line for gas or what?

[tom.mcinerney]

I used regular(SAE 30R7) for most, because it's cheap. But I used SAE30R9 (Hi Press Fluoroelastomer-lined) for new lines over block area, where I'd have to dig/dismantle to attend a leak.
The Helm manual says to use the expensive stuff. I could only think two reasons why, since it's designed for heat/pressure-resistance, nonexistent in our case:
1.) In case vehicle ever used for something else[like gasoline].
2.) To provide resistance to fuel ADDITIVES. Alcohol is used in some. While it's easy to find 'rubber' [elastomers] that resists gas/diesel/lubes, and easy to find rubber that resists alcohol, specifing an elastomer that resists both classes of solvents is EXTREMELY demanding {at least according to a number of charts i looked at). My guess is that the 'biocides', and possibly some of the bacteria byproducts, may also pose a problem [only a guess].