740 fuel line replacement - sizes, advice?
 

Hi all,

Bought a new brick to replace the old brick (740 wagon) as the new one has 170k less miles on it and is comparatively rust free.

Just noticed I have fuel leaking near the fuel filter, the lines are rusted.

Was thinking I could replace the steel lines with high-pressure braided hose.

Any advice on size, pressure rating, installation etc?

Thanks!

Dave

I have only had 240s and never a 740 or 940. The 240s always had plastic gas lines and I suspected the 740s did as well. When I had a leak near the fuel filter on my 240, it was due to a rusted banjo bolt. Someone sells replacement banjo bolts on ebay if that is your problem.

me, I'd use cuprnickel brake line to replace steel fuel lines. easy to bend, easy to make double-flares or whatever fittings, never rusts, will last forever.

Thanks Peirce, that's the first I've heard of that type of line.

volvo invented cuprnickel brake lines in the 70s because steel brakelines rusted in sweden. mercedes adopted them immediately too. the stuff is great for any sort of hydraulic application.

In looking into various fixes, I noted RockAuto has some really inexpensive fuel filters supposedly for my 740, but they have non-threaded nipple-type ends. If I can use them I'm going to buy four to replace both on my two bricks and have two for the next time I need them (I like to replace them every five or six years).

Any reason I shouldn't use flexible high-pressure fuel line (Advance Auto said they have it)?

I see the value in cuprnickel for brake lines as they have to hold very high pressure and not expand (not to mention the anti-corrosion quality), but for fuel (even on fuel injection) it seems a flexible line should work fine and not rust.

Thoughts?

I found this amazing website called Google!

It let me find out that the hose at Advance is SAE 30R9 rated, which has a working pressure of 180 PSI, and that the brick's pump puts out 80, so it should work.

Any thoughts or considerations are still appreciated.

rubber hoses do tend to rot out with age, if the factory used a hard line, I'd probably replace it with another hard line, but if the factory used rubber, go for it. the fuel lines on my motorcycle are BMW EFI pressure hose.

Don't know what the Autozone flexible line was made of. I know that Oreilleys sells the plastic fuel injection line that is the same that came standard on the 240s. It is a hard plastic line - stiff but flexible. This line seems to hold up over time rather nicely as I installed a new banjo bolt on my '90 240 and I was able to cut it and splice in a new piece using boiling water to heat up the plastic to make it pliable for insertion of the splice fittings.