I suspect I have a leak on the fuel line on my '72 250/8. I'm going to buy copper fuel lines and cut them to the right length myself. I've never done this before, so I have a few questions:

What tools do I need? Any special tools, that is.

Do I need to drain the fuel tank first? Seems like a good thing to do...

How do I remove the old lines? Cutting metal near fuel seems risky to do.

How are they attached? Just hose clamps or what?

As you can see, this stuff is new to me, but there's a first time for everything, right?

/Olof Winterfjord

let the tank get low, draining more than 2-3 gallons of gas is not fun!

ive done the copper tube thing before, you probably dont need a bender however it does take a little practice to bend it by hand (or knee!) and you cant get a really tight bend by hand

mike

The rubber clips that hold the fuel line to the underside of the body are still available for a few bucks each. The bending takes a bit of time and patience. The material should be cheap enough for you to have a few feet to practice on.

A hand held pipe bender is under 20$. Like all inexpensive tools, it simply amplifies your skills, for the better or worse. Practice helps a great deal.

-CTH

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OK, thanks for the tips. I just inspected the car and it's clearly leaking, perhaps from the return line as well. There's a wet spot just under the B-pillar.

What do you use to cut the pipes? I've seen these special tools with small wheels, is that the way to go? I'm thinking about temporarily replacing the "bad" parts with fuel hose, as I really don't have time to do it the proper way right now.

I wonder, will this help the engine run better in any way? Because as it is, it runs like A BIG CHUNK OF C***P! Won't run idle to safe its life, impossible to rev it up without pumping the accelerator furiously, and so on. Boy, wouldn't it be nice if this would help!

/Olof Winterfjord

I've used those to cut copper water line, gas line, fuel line, and refrigeration tubing with great success. Most of the rotary cutting tools will accomodate up to 1/2 inch copper line (or metric equivalent). There are typically two rollers and a single cutter wheel. Clamp the line with the tool and tighten up the cutter knob until it is snug. Then run the cutter around the circumference of the line and continue to tighten the cutter knob until you've cut through the tubing. I then suggest deburring the cut edge with a knife blade to get rid of the copper chaff. All you need to do then is let a little fuel run back through the line to make sure there are no copper pieces in the line. You may then use a flare tool to splice in a new piece of line.

I actually had to do this to my car once. The previous owner placed a jack on the main fuel line and pinched it off to the point where very little fuel flowed through. I cut off the pinch and flared both ends of the copper line. I then put in a flare union in place of the removed line and it fixed my problem. It fixed my problem and I only paid about $2 for the union and the nuts.

Olof, it's probably the rubber/fabric braided lines that are giving you trouble.

This happened to me on my 280SEL last Summer...... horrible fuel mileage made me think i was leaking fuel. Tossed the car on my mechanic's lift, but everything looked OK...... then I squeezed one fabric braided line underneath the car and it quickly got wet with fuel.

Hell yes, those 25 yr old rubber fuel lines can become porous and bleed fuel without obvious indication. Its an easy repair with about 4 meters of new rubber fuel line, cut and measured to fit with ring clamps.

So far I've drained the tank and removed the clips holding the fuel lines. There is not an obvious leak, but since part of the fuel line is always wet, I guess there has to be a reason. I'll replace this part with fuel hose to see if there is a difference.

Again, can a small fuel leak make the engine run really bad? Does the fuel pump suck air under high load? Curiosity...

/Olof Winterfjord