What is an acceptable fuel millage rate. My 84 300D turbo gets about 22 mpg. Seems low to me for a 50/50 mix of highway and stop and go driving.

DieselNation

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82 240D - 257k
84 300d - 86k

DN,
I have the 1983 version of your car and I get about 24 MPG pretty consistently. I do about 65/35 city/highway driving and always use fuel additives. Either a full bottle of DFC or 85+, or a few ounces of Power Service stuff. I use Mobil diesel with a cetane rating of 40. I'm doing a valve adjustment which hasn't been done in over 40K miles and I'm hoping that'll increase the fuel efficiency a little bit. good luck

Alex

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1983 300D (parked for four years)
2012 VW Sportwagen TDI Manual
2001 Miata SE
1962 Chevrolet Corvair Rampside

I get 24.4 mpg with my 1980 300TD wagon, using just the walmart diesel and no additives.

I get about 2 and a half weeks to a tank (only 16 gallons since the second the little light comes on for hte first time I'm pulling into the local Diesel station)


I don't have a clue how far that is, but if the time interval changes by a lot then I know there's a problem.

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2005 Audi A4 1.8T CVT -Silver/Black "Siegfried"

1982 300D - Silver/Blue "Ralph" -For Sale:
http://www.peachparts.com/shopforum/mercedes-benz-cars-sale/119226-1982-300d-sale.html#post852260

1989 VW Diesel Jetta Blue/Blue "Bodo" RIP

I have a 1981 300td t wagon that got 27 mpg at 65 over a 200 mile stretch... I was very surprised and pleased... Greg ps. that was with 280,000 miles.....

dieselnation - does your 84 really only have 86k mi???
if so it's only broken in , barely, me thinks..

in my 84 300d t with 186k running straight citgo diesel
with no additives im getting abt 24-25 mpg with mixture in
town and highway driving. it seems to get better mileage
when the outside temps are above freezing.

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1984 300D Turbo - 231k....totalled 11/30/07 RIP

On a recent trip from Northern Cal to Los Angeles we were getting in the 29mpg range with the '84 300TD, 212K, no additives, averaging around 75mph on I5. Overall average for local driving is around 25mpg.

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D

My 2 300SDs always get 25MPG or more. They have the same engine as you do so you should get the same or better because the 300D is smaller and lighter.

Have you adjusted the valves or checked the timing lately? How about the air cleaner. The injectors could be taken to a Diesel injection shop to be tested for leakage and spray pattern and possibly new tips put in. I you have an EGR valve, you might consider fixing it.

These are the things that affect fuel mileage. Don't let anyone tell you to put in new fuel filters. That won't help. You are getting too much fuel into the engine, not too little.

P E H

Thanks for the response. I have just had the valves adjusted, new air cleaner, and had the EGR checked. I also cleaned out the overboost protection valve because it was completely clogged. The car runs MUCH MUCH better. I have not been through a tank of fuel since I did this work so I don't know how the above changes has improved the fuel milage. I have not checked the fuel timing because my mechanic said it is not necessary (24 years experience on Mercedes Diesels) based on the way it runs and starts in the morning. I am concerned with some of the noises it makes, a dull thudding from idle to 2000 rpm and some nailing. I was told by two different diesel mechanics, one Mercedes specialist, and one not, that the noise is probably from an injector that is not spraying properly, but not to worry about it. For now I will keep driving it and see what happens. After reading RunningTooHot's crackhead thread I am also concerned because my temperature runs between 90C and 100C consistently after I replaced the thermostat (tried two different ones and same thing). Could I have the same problem as RTH and could it be impacting my fuel milage along with the noises? I hope not!!?? The car only has 87,000miles.

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82 240D - 257k
84 300d - 86k

I have the same car and an 85-300TD.

The 84 DT gets around 26-27 and the TD gets less.....somewhere around 23-25

Don

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DAILY DRIVERS:
'84 300DT 298k (Aubrey's)
'99.5 Jetta TDI IV 251k (Julie's)
'97 Jetta TDI 127k (Amber's)
'97 Jetta TDI 186k (Matt's)
'96 Passat TDI 237k (Don's
'84 300D 211k Mint (Arne- Undergoing Greasecar Conversion)

SOLD:
'82 240D 229k (Matt's - Converted-300DT w/ 4 speed

Were they MB OEM thermostats?


Also flush out the system REALLY well. A 10% solution of that citric acid stuff does wonders.

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2005 Audi A4 1.8T CVT -Silver/Black "Siegfried"

1982 300D - Silver/Blue "Ralph" -For Sale:
http://www.peachparts.com/shopforum/showthread.php?p=852260

1989 VW Diesel Jetta Blue/Blue "Bodo" RIP

One was OEM, 2nd was autozone special, 3rd was a BEHR.

DN

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82 240D - 257k
84 300d - 86k

Overheating problem solved


here's the summary of my problems with overheating and how I solved them.

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2005 Audi A4 1.8T CVT -Silver/Black "Siegfried"

1982 300D - Silver/Blue "Ralph" -For Sale:
http://www.peachparts.com/shopforum/showthread.php?p=852260

1989 VW Diesel Jetta Blue/Blue "Bodo" RIP