I have a substantial diesel leak. Left a foot diameter puddle on the driveway. Seems to leak most just when the car is started from cold (its 30F here), and interestingly, it continued to leak for a time after I turned the car off. When I turned the car back on to test, it doesn't seem to leak (once warm). I have not been able to "catch it" (i.e. be under the car and watch where it is coming from)

Its hard to see, but the best guess I have is that it is coming from the yellow plastic piece where diesel enters the pump. The other candidates are the two hoses exiting the top of the pump. I have replaced the rubber on the line from the inline fuel filter to the pump.

Is that yellow piece supposed to be able to rotate? (it does on mine).

Anyone have other suggestions?

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1989 190D 146,000km

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W201 1989 190D

That's the fuel thermostat. MB sells an o-ring for between that yellow plastic thing and the case of the thermostat. I think there's a rebuikd kit with more bits and seals including the plastic yellow thing. You can probably bypass the thermostat until you get parts. Some folks bypass it permanently. Fuel is heated by engine coolant so it does nothing until the engine is warm.

Sixto
83 300SD
98 E320 wagon

Thanks Sixto! Showing my ignorance. Have found a good post on bypassing it.

One the fuel lines are removed from the fuel thermostat, I presume it is held to the block with a couple of bolts? (i.e. no oil lines to it).

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W201 1989 190D

The fuel thermostat is held to the block with 2 screws. Once you delete it, you can remove any excess hoses as well. I deleted my fuel thermostat for similar reasons. I did try to repair it, but it stuck in heat mode. It never gets very cold in my climate, so bye-bye it went.

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Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

If anyone has any addition questions or is looking for a DIY on leaking injectors/fuel pump; check out the tech article link below.

Mercedes-Benz 190E Fuel Pump Replacement | W201 1987-1993 | Pelican Parts DIY Maintenance Article


-Dmitry