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1986 560SL 1986 420 SEL
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117 Posts
Discussion Starter #1
Hi everyone,

I was under my 560 sl today and I saw some fuel leaking from the fuel pump assembly. I checked every fitting by putting some dry clean paper towel around each one to identify which banjo fitting is leaking. All dry yet I still have fuel dripping from the forward pump.

As best I can tell the leak is in the pump itself. Right where the end cap is fixed to the body. Seems like an improbable place to develop a leak.

Has anyone seen this park leak before?
 

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R/C107 Moderator
1986 560SL: '84 500SL: '84 280SL 5 speed: other 107s
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32,162 Posts
Never seen it nor heard it reported. How is the rest of the system? Two things I can think of.
1. Manufacturing defect.
2. Blockage down stream causing too much pressure.
 

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Registered
1986 560SL 1986 420 SEL
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117 Posts
Discussion Starter #3
The pumps are original (88k. miles). I am preparing to do a fuel pressure check at the distributor. Might as well do a volume check too. That could tell me if the lines are blocked. Had the fuel tank out and it was remarkably clean so I think the lines are too. But could be blocked. I can't a dually see where the leak is coming from. Even removed the wheel to get a better look at the end of the pump. I'll have to look at it more today. Could leak way the end clip but seems unusual, that's why I ask if anyone else has seen this. I have owned this car for 18 years next month.
 

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1986 560SL 200,000 km
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62 Posts
One of my fuel pumps started leaking in a similar way when the seal between the top and the main body failed due to age 3 years ago. The way that gasoline often creeps from a leak makes it dificult to tell exactly where it is leaking from. Replacement of the pump is the solution. I chose to replace both pumps and most of the readily available components in that assembly since I didn't want to have to drain the fuel system a second or third time. I didn't replace the screen in the tank (which is recommended), instead, I inspected the tank, lines, fittings etc for signs of rust & debris. I was satisfied and chose to roll the dice regarding the tank screen. If that screen fails and the tank has rust & debris, the new pumps may be ruined.
 
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