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Tracing return line on 6.9 hydraulic tank

Started by Rolo, 06 September 2023, 08:09 PM


Hi everyone, I had to replace my high pressure pump a few years ago when the factory installed unit developed a hairline crack. I got a rebuilt pump from the guys in Germany that do a lot of old parts.  I reused all of the fittings and torqued to factory specs.  Now the return line fitting is seeping a lot of fluid so I got a replacement fitting thinking the existing might be slightly misshaped from disassembly and reassembly.  I bought a new fitting and a local shop sourced an oil-proof hose to fit.

I got the car up in the air and I trace the tank line, not to the spigot on the bottom of a tank, but to a metal tube that disappears parallel to the radiator.  What?  Where does that tube go?  FSM diagram shows return line going straight to the fluid tank.

Thanks for any insights on this mystery.


This is a cooling loop running under the radiator.  Good ol' German overengineering at its finest ;D
1977 450 SEL 6.9 - Astralsilber


Thanks and I take it you're not kidding.  A trombone line under the radiaot to cool?