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  #1  
Old 02-18-2008, 11:32 PM
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Location: st louis
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replacing leaky return fuel lines

the return fuel lines on the drivers side rear of my 85 300TD seep, and leak diesel fuel out of the drain under the spare tire.

before I attempt to cure my beloved wagon's incontenance, any helpful hints from you pros would be gratefully accepted.

specifically, where do these lines originate/lead to? procedurally, which end should I clamp down on first with the old vice grips in order to prevent air getting into the line?

i've read that it's critical not to allow air into the fuel line, otherwise you have to bleed the system. idiot-proof me here if possible. worst case scenario, how do you bleed the system? i know where the knob is for the pump, but do you turn the nut on top of the filter housing counter-clokwise a bit, and then pump, or is it vise-versa?

thanks...........

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Old 02-19-2008, 12:06 AM
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No worry about air getting into the lines. Wait until your tank is very low. Then remove the return line under the hood and install a length of fuel hose from the engine side into a fuel container. Drink a cup of coffee and idle the engine until it stalls and all the fuel is pumped out of your tank. Replace all the bad fuel lines, probably a good time to replace the rubber feed line out of the tank also. Pour fuel from container back into tank. Start it up.
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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13
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  #3  
Old 02-19-2008, 12:11 AM
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Can you see the leaky lines under the car? There are two steel fuel lines leading up to the engine, and where they connect to the tank, they are flexible. Are these the leaky lines? I ask because from where you're describing the leak location (from the spare tire) it sounds like the leak may be coming from the lines leading from the main tank to the expansion tank...it a small metal tank just forward of the spare tire...you can see it when you pull off the spare tire cover. On my car I don't think I can see these lines from underneath...I may be wrong though. But you would have to pull up your rear seat (3rd row seat) if you have one or just the rear floor liner, to get to one end of these lines...and the other end is at the expansion tank. On mine, they run between the top of the fuel tank and the bottom of the car floor, so they're probably hard to run. Just a guess, but it my require you lowering the tank a bit.

The good news is you don't have to worry about introducing air into the fuel system if its those hoses. If you don't disconnect the flexible lines that connect the tank to the steel lines, you'll be all right as far as air goes.
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Old 02-19-2008, 12:17 AM
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Quote:
Originally Posted by kerry View Post
No worry about air getting into the lines. Wait until your tank is very low. Then remove the return line under the hood and install a length of fuel hose from the engine side into a fuel container. Drink a cup of coffee and idle the engine until it stalls and all the fuel is pumped out of your tank. Replace all the bad fuel lines, probably a good time to replace the rubber feed line out of the tank also. Pour fuel from container back into tank. Start it up.
Holy primer pump Batman! Wouldn't this require a lot of priming once you filled the tank back up? Did I miss something?
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1985 300TD-euro 352,000 mi
1974 240D (1?)52,000 mi - has a new home now
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  #5  
Old 02-19-2008, 12:38 AM
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No priming at all when I did it. Fired right up. Ran at reduced rpm's for about 20 seconds then back to normal.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13
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