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  #1  
Old 07-19-2007, 05:29 PM
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mpg on a 1984 300DT

I only get about 24 mpg in my 84 300DT, i alredy changed both fuel filters airfilter, fuel lines, banjo bolt, valves adjusted, oil changed (rotella). I usually cruise at 65 mph and its 90% HWY. What could be wrong??


Thank you

BTW: what is the parts number for the alda banjo bolt??


Last edited by 94mgm; 07-19-2007 at 05:47 PM.
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  #2  
Old 07-19-2007, 05:34 PM
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valve adjustment
camshaft timing
valve timing

The best you will likely get from that vehicle is 27-28 mpg under the conditions described.
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  #3  
Old 07-19-2007, 05:43 PM
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i did adjust the valves, but how do i check the latter two??
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Old 07-19-2007, 06:02 PM
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mmmmmm Diesel...
 
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Do you use your A/C? I get better mileage in cooler weather when the A/C is not used.
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  #5  
Old 07-19-2007, 09:56 PM
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24mpg is normal, especially if you use your A/C.
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  #6  
Old 07-19-2007, 10:14 PM
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I second that 24 is normal. I have 3..
78 300 D na 23-25mpg
85 300 D 22-26mpg
79 300SD 18-23 mpg

All are ranges hand calculated over the last year. Lower mpg when cold out, higher mpg when hot out.
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  #7  
Old 07-20-2007, 07:23 AM
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hmmm... My 2.3 ton 5.7 liter cadillac with 260hp got better mileage @80 MPH. I thought these cars did better...

Thanks though
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  #8  
Old 07-21-2007, 09:10 PM
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Quote:
Originally Posted by 94mgm View Post
I only get about 24 mpg in my 84 300DT, i alredy changed both fuel filters airfilter, fuel lines, banjo bolt, valves adjusted, oil changed (rotella). I usually cruise at 65 mph and its 90% HWY. What could be wrong??


Thank you

BTW: what is the parts number for the alda banjo bolt??
In addition to the above check: tire pressure (try 32 psi front/rear), condition of wheel bearings, brakes to see if dragging at all. If your front end alignment is out of whack, this could also reduce mileage

At 70mph driving pure hwy without the AC my 83' 300D will get 27mpg. A mixture of city and highway driving will reduce the mileage to around 25mpg. The mileage you describe sounds pretty normal.
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Old 07-22-2007, 02:37 AM
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That MPG sounds normal for my MBs too.
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1983 MB 300D - > 430,000 miles - Deep Blue - Bilstein Comforts - 0-60 in 24 seconds - 27MPG
1985 MB 300TD (wagon) - > 275,000 miles - Manila Beige - Thule rack - 0-60 in 18 seconds - 22 - 25MPG
Biodiesel, Mobil Delvac 1, and Viton fuel lines!
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  #10  
Old 07-22-2007, 04:42 AM
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Quote:
Originally Posted by 94mgm View Post
hmmm... My 2.3 ton 5.7 liter cadillac with 260hp got better mileage @80 MPH. I thought these cars did better...

Thanks though
The wonders of overdrive
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  #11  
Old 07-22-2007, 01:46 PM
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My 83 300TD got 30 @ 60 mph without air on.

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