I've replaced this particular fuel line on my '82 300sd, and I suggest using only the proper replacement fuel line. It fits perfect and is worth the bit of extra money. If one hose crumbled then, most likely, all the other hoses are ready to spring a leak too, so you might as well replace all of them. It's better to do that then to regret it while you're on the highway.

I tried weed-eater line, and it didn't work for me either, but maybe you have different stuff.

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1982 Mercedes-Benz 300SD TurboDiesel - Silver
1985 Mercedes-Benz 500SEL - Maroon
1974 Mercedes-Benz 240D - 4 on the floor, My 1st Car!! - Pearl
1985 Nissan 300ZX Turbo - Auto to Manual Tranny conversion - Black
1991 Volvo 940GLE - My everyday driver - Pewter