Steel Fuel Line(s) Leaking... - PeachParts Mercedes-Benz Forum

bjcsc · #1 01-02-2005, 09:13 PM

I am 99% sure that I have at least one steel fuel line leaking directly above the rear axle carrier. I only had time to briefly look at it today, and will look at it in more detail tomorrow. I could see the lines were corroded right at the point where they bend above the carrier (there is a rubber fitting, similar to a plug wire separator at the same point). I will add a pic in an edit tomorrow. So what is my best option?

Use rubber fuel line to replace the 4" or so of corroded line (as others I found searching did)
Replace all steel lines, ordered from ???
Buy a roll of ?mm line, steel?, aluminum? then bend it and replace fittings?

boneheaddoctor · #2 01-02-2005, 09:23 PM

Quote:

Originally Posted by bjcsc

I am 99% sure that I have at least one steel fuel line leaking directly above the rear axle carrier. I only had time to briefly look at it today, and will look at it in more detail tomorrow. I could see the lines were corroded right at the point where they bend above the carrier (there is a rubber fitting, similar to a plug wire separator at the same point). I will add a pic in an edit tomorrow. So what is my best option?

Use rubber fuel line to replace the 4" or so of corroded line (as others I found searching did)
Replace all steel lines, ordered from ???
Buy a roll of ?mm line, steel?, aluminum? then bend it and replace fittings?

do the rubber line repair thing till you source out the steel line to replace when weather is more friendly to outdoor work.

whunter · #3 01-02-2005, 09:49 PM

Any auto parts store should have 3/8 bulk steel tube.
A 22 foot roll should be under $20.00 USD.
Not a fun job.
Use 3/8 inside diameter hydraulic hose or flare fittings to join tubes.

bjcsc · #4 01-02-2005, 10:02 PM

Quote:

Originally Posted by boneheaddoctor

do the rubber line repair thing till you source out the steel line to replace when weather is more friendly to outdoor work.

Ha! Average high here over next 10 days is 72deg...

Quote:

Originally Posted by whunter

Use 3/8 inside diameter hydraulic hose or flare fittings to join tubes.

OK, so is 3/8" the right size? I was thinking 8mm or 5/16" based on what I read searching...Are you suggesting just replacing the damaged part? What about aluminum?

boneheaddoctor · #5 01-02-2005, 10:05 PM

Quote:

Originally Posted by bjcsc

Ha! Average high here over next 10 days is 72deg...

OK, so is 3/8" the right size? I was thinking 8mm or 5/16" based on what I read searching...Are you suggesting just replacing the damaged part? What about aluminum?

72 degrees.....you are one lucky stiff................it will be months before I see 72 degrees.

Follow Whunters advice......He knows his stuff.

bjcsc · #6 01-03-2005, 11:33 AM

I have confirmed that one is in fact leaking. Here's a pic of the point where the leak originates:

I guess I'm off for parts with the intention of splicing a section of new line in at the points seen below. Will post an update at the end of the day.

So unless there are any major objections/concerns in the next hour or so, that's my plan. Comments?

boneheaddoctor · #7 01-03-2005, 02:55 PM

Sounds good.......that will work.

Hatterasguy · #8 01-03-2005, 03:05 PM

I had to do this last spring, my fuel lines rotted threw above a rubber hose repair from the PO. I used 5/16 break line if I remember correctly, it was almost an exact match to the stuff MB used. The autoparts store even lent me the tools to bend and flar it, not to bad of a job. But check your brake lines!!! I started off with a fuel leak but found a few of my brake lines were almost rotted threw!

I'm glad I caught those!

leathermang · #9 01-03-2005, 03:10 PM

Splicing steel line is a real pain...
consider taking brass sheet stock and JBWelding it over the patch.. making as big a patch as you an fit into that area....
I have patched steel tractor fuel tanks this way which are still holding 20 years later....
Naturally Cleanliness is critical ... sand till bright... and wipe down with alcohol then mix JBWeld as per directions and apply fast.... and then some warmth... maybe a hairdryer two feet away... and don't touch the car until 24 hours later....

I don't know about steel fuel lines... but steel Brake lines REQUIRE A DOUBLE FLARE end....

rwthomas1 · #10 01-03-2005, 03:11 PM

I have never spliced metric tube to SAE before but if the diameters are close enough then the flaring tool should grab onto the metric stuff well enough to work. Loosen the retaining clamps along the underbody so you can pull the lines away without bending them too much. Worst case scenario is that you cannot get the flaring tools to work and you have to install rubber line untill you get the correct tools to do the job. Take your time and do it correctly the first time if possible. RT

bjcsc · #11 01-03-2005, 07:03 PM

Well, I'm into it pretty good right now. I did get some 5/16 steel line. It is very close to what is there, just a shade smaller ( by a shade I mean thousandths). I decided to go with compression fittings vs. flaring after trying to flare some first and discovering that the flaring tool I bought doesn't work so well on steel, at least not for a double flare which is what the fittings I bought required. So, currently one is completed. However, even after loosening everything to give me enough play to work with, the little manipulation I did do caused yet another leak up by the driver's front wheel, at another point where the lines are inside a rubber fitting. When it rains it pours. I would rather find it now than later I guess. I suppose it could be worse - I could have rust in other places and I don't. Well, I'm off for more fittings..

bjcsc · #12 01-04-2005, 09:04 AM

I finished last night around 10 or so and put a piece of cardboard under each fix. This morning there were no drips! Whunter should be considered for the understatement of the year award for stating "not a fun job"; Working around the rear axle carrier was like building a ship in a bottle. Thanks for everyone's advice.

Monomer · #13 09-01-2006, 10:24 PM

I'm going to bump this because it's what I've been struggling with for the past week.

It originally started out as a faulty brake line. Traced the line to right below the master cylinder. The Clamps were the problem. Moisture gets trapped in them and over the years it corrodes them.

I replaced (patched) 3 fuels lines and put in 2 new feet of brake line. This in on a w126 Gasser. I patched the supply line with some goodyear fuel injection rubber hose (rated above 90PSI) Supply lines were (the much cheaper) 50psi tubing. For the patches I used the tubing, cut to two inches longer than needed, the proper hose clamps, and a flaring tool (borrowed from work, this model sells for $250, and has a built in clutch; so you dont break the flare)

Procedure went as follows:
-Unplugged the battery (pump may stay on) and let sit overnight (let the pressure srop)
-Cut lines with pipe-cutter (be SURE to de-burr, or else you get a nasty flare)
-Flared lines
-Hung clamps on pipe (it's a pain to forget...)
-Twisted on the fuel tubing (tight fit, due to the flare) leaving 1Inch overhang on each side
-Tightned hoseclaps (clamp positined right after the flare, to give an airtight fit)

For the brake line:
-Took old line out
-Bought a pre-fab brake line (murrys) (metric/japan/import BUBLE FLARE fittines on both sides)
-Pre-bent the line to what the old one (roughly) looked like
-cut one side of the tubing off, replace MALE bubble flare fitting with Inverted flare type, Deburred and made an inverted flare
-Flared the car's brakeline (again DEBURR)
-Using a Import/Japanese (it's what the case said) Union, join the two flares
-Bleed (preferably power bleed)