GuardsRedHammerhead

OK. So, I promise that I have read EVERY fuel line replacement document and thread on Rennlist, but still can't find my answer.

So, I am wanting to spend my afternoon replacing the injection Fuel Lines on my S4. I have been sitting on the fuel line replacement kit from Roger with the NEW style "U" shaped hose in the back of the engine. The instructions in that kit say to use NEver Seize on the threads of the fittings. I have mechanic buddies, who have never touched a 928 (or any other civilized car for that matter ) who are telling me to use Teflon tape on the fittings. OK, I don't think so.

What is the general concensus from the 928 experts on this forum. What prep materials do I need to knock this out this afternoon. Some threads indicate to use NOTHING to prep the threads and just screw them on. I want to make sure I have no leaks.

FUSE69

The cone at the end of the fitting is the sealing surface, so the threads serve no sealing function... DO NOT use teflon tape! These are not NPT fittings...

You could use nothing on the threads, but a bit of never seize won't hurt for any future disassembly.

SeanR

My opinion:

Do not ever, ever, ever, ever, ever, ever, use Teflon tape in a fuel fitting.

Clean the threads on all the connections, put back dry.

Shane

I sure wish someone had used never seize on all of mine, those damn fittings can be a bastard to break loose after 25 years of corrosion. I however did put a dab of it on the threads when I reinstalled new lines. to each his own, but teflon tape will end up clogging your injectors for sure.

Mrmerlin

put some never seize on the back sides of the cone ridges and the threads of the connections,
then when you have to remove the connections in 15 years they will come apart easily.
I use antiseieze on every fuel line install, as well as the threads on the oil cooler fittings.
If you have never had to destroy a fuel cooler from frozen collar nuts you wont understand why

ROG100

The instructions for the use of anti seize are written by Greg Brown - and if Greg says use anti seize that is good enough for me.
This is only on the new U hose.

linderpat

the reason you didn't find a definitive answer in your exhaustive thread search is because you never searched the scorched car threads
Never use teflon tape on fuel lines. Instead, do as MrMerlin says and use antisieze (a little dab) or put on dry like Sean says. Either is okay. Also do not over tighten, that could lead to leaks as well.

GuardsRedHammerhead

Thank you all for the input. Didn't get the fuel lines completely done, yesterday, but I did rebuild the tail\stop light harnesses using the NAPA "fix". Worked fantastic, and was damned inexpensive. It is nice to have nice, bright, tail and stop lamps that actually work and don't throw red error lights on the dash every time I touch the brake pedal.

MainePorsche

✓.

the flyin' scotsman

As well as the above advice NOT to use teflon tape and only reassemble dry/small amount of anti-seize you should aslo have a good set of flare wrenches of the right sizes.

These wrenches get fittings loose that have been together for a long long time.

When doing the rear U hose I find it easier to remove the regulator and rear fuel damper as an assemble then reuild on the bench.

After all is back together you can pressure test all the lines before starting the engine by jumpering the fuel pump relay.

Good luck.

GuardsRedHammerhead

Excellent advice and will build my jumper, today. Thank you.

GuardsRedHammerhead

Any of you guys ever do your fuel line job, but sit and stare at it for hours before starting it.

It is almost buttoned up, and I will "FIRE" it up tonight.

A bit nervous of my skills, when it comes to things that can burst into flames. I will try the fuel relay jumper pressurization test tonight.

Anyone have any advice or technique for doing it? Is there a maximum amount of time that the pump can run during the test?

the flyin' scotsman

Pull the pump relay and jumper per the WSM. The pressure will build very quickly and any leak will be very evident.

Leave the air filter assembly off and look down at the rear damper and regulator, all the connections, the fuel rails and the main fuel feed line.

I did go over my first project many times.........now its routine but still with great care.

GuardsRedHammerhead

My biggest concern was the fuel line from the cooler to the Regulator on the passenger side of the MAF. The line is steel, comes out of the engine side of the regulator and heads an inch towards the front of the car, makes a U-bend and heads under the regulator (has a 8mm bolt that holds it to the mounting bracket of the regulator and then heads toward the cooler, where it transitions to rubber. I cut all the metal skirts off with, ready for this, a Key cutter that you use to make car keys. They cut REAL quick. After putting it all back together with Roger's kit, I had a hard time getting the steel portion to bolt back up against the regulator bracket without forcing the fuel line to be offset in the regulator, a bit. I am hoping that the tightening of the nut going to the regulator straightened out the fuel line inside the regulator. I guess I will need to take pics to make this mean anything senseful.

Bill Ball

The metal lines can get bent easily so they may not line up. Also, the pressure regulator and dampers are rigidly mounted and taking them on and off can change the alignment. Their mount bolts are not very accessible, so there can be some trial and error there. They need to line up perfectly and the nuts should spin on pretty easily. In theory the ball and socket ends allow for some variance, but they really need to be right on. Once you think you are done, jump the fuel pump relay and look, smell and FEEL for leaks. I have had some instances where things looked OK, but when I ran my finger under each of the joints, it came back wet on one or two joints that seemed to have gone together just fine. In one instance with my car, I had to remove the rails and dampers and assemble it off the car to see that the alignment needed tweaking to get it to seal.