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'96 sl500, 87 300td
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134 Posts
Discussion Starter #1
I have just run the second full tank of fuel thru my newly aquired 87 300td turbo. Very disappointed in by mileage. First tank averaged 24.1, second tank averaged 22.5. I was expecting something around 28 to 30.

Afdter I purchased the car I sent it to the shop for a full service. Changed the Air Cleaner, Fuel Filters, Transmission filter and fluid, Rear End oil, Power Steering & Rear Suspension fluid, Engine Coolant, Brake fluid, front rotors (Drilled & Slotted), ceramic pads and 7 by 15 8 hole replicia wheels (have had wheels for 10 + years now on their 3rd car) with 215 60 15 tires (Recommended by Tire Rack).

This is my 5th MB Diesel, I have had a 69 220d, a 79 240d, a 84 190d 2.2 and a 87 190d 2.5 turbo. I averaged 29 to 32 miles per gallon with all these cars. What's wrong.

Any one have any suggestions?
 

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2001 CLK430
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107 Posts
You didn't mention any injector service. I'd suggest running some concentrated Lubro-Moly through the fuel system to try purging the injectors. Add some to the tank as well, then give the car a good italian tune-up to blow all the crap out.

Some people have reported power and economy gains by plugging the vacuum lines that go to the passenger side of the car. This bypasses the EGR and some other emissions, so it is an "off-road only" fix [}:)].
 

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'96 sl500, 87 300td
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134 Posts
Discussion Starter #3
Sorry for the delay in getting back, vacation with no laptop. He did check the injection pump, replaced the return hoses and 2 glow plugs. I have taken your advice and put in a can of injector cleaner. Sat at the airport for a week and hopefully I will see a differance in a few tank fulls as I will continue to add injector cleaner at every fuill up.

On my previous diesels I frequently added 3 to 4 ounces of Marvel Mistery Oil and found that the engine and injection pump ran quiter. Any one else out there use it?
 
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