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I love my W140!

As of lately the old gal has started to lose power over time. Today is worse than usual... push the pedal while cruising 60 MPH on the highway and it doesnt go any faster. She is in need of some attention. I am just curious where to start. I have had the car for 15k miles and done just oil changes.

She has 190k miles on the clock

any help would be greatly appreciated!


-Will
 

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1995 mercedes S420
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228 Posts
I love my W140!

As of lately the old gal has started to lose power over time. Today is worse than usual... push the pedal while cruising 60 MPH on the highway and it doesnt go any faster. She is in need of some attention. I am just curious where to start. I have had the car for 15k miles and done just oil changes.

She has 190k miles on the clock

any help would be greatly appreciated!


-Will
start with the spark plugs ,coils,and wires. and check the fuel filter and fuel pump . sometimes fuel pumps dont pust that much gas into the car. ur car got 2 fuel pumps
 

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94 s350, 93 dodge cummins 250
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95 Posts
always start with the fuel filters on a diesel.

it will cause power issues

vacuum issues will cause the turbo to not work so changing to a pressure wastegate will solve that forever. search for that on all mercedes diesel sites and you will get your answeres.

this site is mostly gas oriented as the 3.4 diesel isnt very popular

i love mine though

Steve
 

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1984 MERCEDES-BENZ 300 TURBO DIESEL, 1978 CHEVROLET K20 CUSTOM DELUXE
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365 Posts
Hello, I am stopping over from the w123 forum, One day i will own a w140. Anyway i have a 1984 300 turbo diesel. right now i am experiencing the same problem as you. Your top speed will start to get lower over time and you hit the accelerator and nothing happens. FUEL FILTER. Most likely your engine is starving for fuel and i would say you are over due for a fuel filter at 15000mi. Now my car has a inline pre filter and a screw on fuel filter. I am not sure how they set up the w140 diesels but you may also have more than one filter. Also if you did not know algae can grow in the fuel tank. What happens is if your car sits for a while and you don't have a full tank of diesel condensation will develop and algae will start to grow. It will eventually keep growing and travel throughout the fuel system. You can put a biocide or startron in the fuel tank to help clear it up IF you have algae. Sometimes clumps can break off and clog the fuel filter and you will get a loss of power. I am not in anyway saying you have algae in your fuel tank so don't worry. You should just have the fuel filters changed at a shop or do it yourself and you should be fine. Happy motoring.:D:D
 

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1988 190E, 1988 260E 5Speed, 1995 E300D, 2001 ML320, 1977 Mercedes 450Slc
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65 Posts
change fuel filter and, i would also run purge throug it because it cleans all fuel lines, injectors and pump, also check air filter

does it have any kind of smoke
 
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