I have exactly the same experiece. I'm going to take care of the dragging brake problem (I hope) this weekend and see if that helps. Otherwise, I get 20 mpg consistently. My dad always got about 24. My motor has about 250K on it, it starts right up, hardly smokes at all, it just doesn't get good mileage.

Frank.

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'82 300SD

I get about 40 mpg on the highway ay 60 mph. I just do the regular maintenance and use diesel purge and redline 85+.

My dad used to have a 93 300D 2.5 Turbo and he got mid- to upper-30's on the freeway. He drove it from like 60,000 miles to about 115,000 miles. He always used Rotella T and swore the car was smoother as a result.

I had a 1980 300D non-turbo and always got 24mpg. Never a mpg more or less. I'd end up filling up at about 500 miles per tank, but went all the way to 550 miles per tank--was pretty scared. I adjusted valves, ran Sea Foam in the fuel, ran the STP (I think it's STP) diesel injector cleaner (light blue bottle?) and changed oil frequently with Valvoline All Fleet Plus. Still, 24 mpg. City, highway, mixed, 24mpg. I had flaring tranny and progressively worse and worse acceleration. Combined with the rust problem, I donated it to a local automotive school. Bought it with about 116,000 miles and donated it with about 140,000.

I also later had a 1987 300 SDL. That car with the EGR host plugged just rocks. Always high 20's mixed, excellent acceleration. Had about 180,000 when I got it and about 210,000 when I sold it. Had incredibly stiff steering (Didn't want to change steering box) so I sold it to go back to a Town Car. I'm a computer professional and have problems with my wrists and arms--driving that car for a couple hours per day wasn't helping. I loved it though, it really was fast.

I also had a 1987 560 SEL. Solid 13mpg. No more no less. Probably too much flooring it to get any more then 13. Couldn't resist in that car.

My 96 Town Car with 4.6L V8 on regular unleaded gas gets about 18 mixed. Freeware should get 22-24, city or lots of fast driving about 15-17. I have fantasy's of dropping in the Ford V8 turbodiesel from a F250 into a Town Car.....


What's a typical early 80's 240D with manual transmission get for milage? Upper 20's city, mid 30's highway??? Driven nicely, of course. Would a K&N or a air intake modification to more of a ram air setup help? Or larger exhaust pipe diameter, less restrictive muffler (and lose the center muffler) ? I saw a cheap one for sale and thought it could be a nice project.

Anyway, keep changing that oil.....

-m

PS: Wife's Alfa get's about 23mpg with the standard medium-agressive wife style driving...

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Now:
2018 Tesla Model X
1999 S500 Grand Edition 164k
1992 300D 2.5 Turbo 287k
2005 E320 4MATIC wagon
1991 Alfa Romeo 164L 99k (sleeping for a while)

Then: 96 Lincoln TC, 93 Lincoln TC, 87 560 SEL, 87 300 SDL, 80 300D, 89 560 SEC

Hi,

Just finish major service on my 85 300D. I was getting a consistant 20 MPG no matter how I drove the car.

POP checked the injectors.. were okay. Adjusted Valves.... they were tight.. and MOST importantly -- adjust the IP. I found it was off 6 degrees. I am now getting 25-28 city driving. I don't know about hwy yet but I am expecting 30+.

Search your record people... IP injection timing should be checked at least every 60K. Its just as critical as the value adjustments IMO.

Morph

Sorry, what's IP? And how do you check it?

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Now:
2018 Tesla Model X
1999 S500 Grand Edition 164k
1992 300D 2.5 Turbo 287k
2005 E320 4MATIC wagon
1991 Alfa Romeo 164L 99k (sleeping for a while)

Then: 96 Lincoln TC, 93 Lincoln TC, 87 560 SEL, 87 300 SDL, 80 300D, 89 560 SEC

The IP is the injector pump. It attached to the side of your engine and has the metal fuel lines running out from it to your injectors.

Adjusting it is a tricky thing. My indy adjusted mine for me since I didn't have the proper tools. I watch him adjust it which took a total of 2.6 hours but I couldn't repeat all the step he did in proper order. My suggestion is to leave this to a MB pro. This didn't seem like a DIYer type job. Some other in forum may argue but its involved. My indy has been doing this for 26 years. He told me himself, he has learned many tricks over the years which are not in the manual.

Might get NCARTER or Larry to chim in and explain since they both are doing motor rebuilds.

Morph

Maybe I'm an idiot, but I thought that the valves on the 602 engine in the 90-93 300D did not need adjustment every 15k miles like the old 617 motors. I had the valves done on the old 300SD every 15k, but I haven't touched the valves on my 300D. Am I neglecting basic maintainance? And is that why I'm averaging 26 mpg in combined driving?

I have new fuel filters, a new air filter, I run Mobil 1 tri-synthetic 15-50, and I use 85+.

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Ben

The MBs:
1976 300D (W115) - 330K and still going (sort of)
1991 300D 2.5 Turbo - Sold at 221K
1983 280SEL - Sold at 206K
1981 300SD - Sold at 232K