I am wondering if there are supposed to be two different sizes of vacuum line around the engine, because there already is in my car. I never noticed until one broke, that it is much larger than many others around it. And I didn't think it odd until going to order more line of that size, when all there is on every MB parts site [I know of] are the small 4mm size lines. I've got tons of this small diameter line, is it okay to use anywhere firewall forward?

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1981 300SD, odometer stopped at 188,000

Yes, there seems to be skinny and thick types.

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1979 240D- 316K miles - VGT Turbo, Intercooler, Stick Shift, Many Other Mods - Daily Driver

1982 300SD - 232K miles - Wife's Daily Driver

1986 560SL - Wife's red speed machine

I have these rubber lines that are the same size as the larger ones, would it still function the same or does it HAVE to be the traditional hard plastic?

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1981 300SD, odometer stopped at 188,000

The rubber lines will work as long as they don't collapse. They will take up more room and probably won't last as long. If you've got a bunch of rubber hose sitting around, might as well use it.

Jeremy

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970