Author Topic: Fuel Return Line in Tank in R107  (Read 981 times)

John Moore Sr

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Fuel Return Line in Tank in R107
« on: 24 September 2020, 07:33 AM »
I'm in process of reviving the 380SL from an extended sleep. I had to pull the tank to clean out some rust and Dino sludge.  The return line that winds it way to the bottom of the "swirl" chamber appears to be very restricted when compressed air is applied. I can hear a small flow of air exit the line. My questions are: does the return line have a intended restriction like a orifice or such to provide some sort of balance to the system? Should it flow freely?  Thanks in advance.  JMSr
1970 300SEL 3.5, 1972 350SLC Euro Parts car, 1974 350SL Euro 3.5 V8 4 speed, 1978 450SLC Euro. 1979 6.9 #4630 1979 6.9 #7003 Parts Car, 1980 450SLC Parts car, 1985 380SL...and once had 1975 6.9 #142 until JuNIOR commandeered it.

daantjie

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Re: Fuel Return Line in Tank in R107
« Reply #1 on: 24 September 2020, 10:24 AM »
Maybe post a pic if you can
Daniel
1977 450 SEL 6.9 - Astralsilber

rumb

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Re: Fuel Return Line in Tank in R107
« Reply #2 on: 24 September 2020, 11:29 AM »
I believe this should be free flowing. Shouldn't you be able to poke a wire in the tube to clean it?
'68 250S, '77 6.9 euro, '91 300SE, '98 SL500 '14 CLS550

John Moore Sr

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  • W116 and R/C107 Enthusiast
  • Location: Washington NC
Re: Fuel Return Line in Tank in R107
« Reply #3 on: 24 September 2020, 01:06 PM »
After some ponder and percolation, I decided to try rodding the line out. I used a speedometer cable with the end ground to a point. It made it through the 90 degree turn and stopped almost half way to the outlet.  Not where I had expected the blockage to be. No amount of twisting and pushing on cable would clear the obstruction. Behold, it seized and wouldn't come out. A great amount of reversed twisting of cable finally freed it.  I then decided to put compressed air on line again, and Presto !, I had cleared the blockage.  I then was able to get cable all the way to the junction at the Swirl bowl. I could see the cable by looking from top down through the sending unit opening.  I deem it to be a successful procedure.  We shall see.  JMSr
1970 300SEL 3.5, 1972 350SLC Euro Parts car, 1974 350SL Euro 3.5 V8 4 speed, 1978 450SLC Euro. 1979 6.9 #4630 1979 6.9 #7003 Parts Car, 1980 450SLC Parts car, 1985 380SL...and once had 1975 6.9 #142 until JuNIOR commandeered it.