I just bought a Mercedes 300D - It's beautiful, an '80 with only 134k, and I love it, but it is EXTREMELY slow going up even the slightest grade. I expected it to be slow off the line, and merging, and for it to be slower on hills, but this is ridiculous! I didn't hit any big hills on the test drive - didn't even think to, and on the way home was struggling to barely go 15 or 20 up a larger hill and seriously thought I might not make it. Even on a slight grade it seems to lose a ton of power immediately - I've cruised on flat highway at 75 easily, but at times (was there a slight grade?) I had it floored and it wouldn't go over 60. Are these cars just totally gutless in general, or are there some adjustments/things to look for that might help? I'm wondering if I should get a turbo diesel instead. I really don't need a super zippy car - I mostly just drive my kids around town, but for the occasional hill, I'e truly never seen anything like it (even when I used to drive an old VW bus!)...The slowest of slow trucks were passing me and I think I singlehandedly caused a traffic jam...
I'm hoping to keep this car, can anyone HELP?
Thanks,
honeytiff

Welcome to the forum

1) Pull on the knob just above your left knee. With the E-brake off it goes faster.

__________________
'87 924S
'81 280SEL

Sold ->

81 300SD -
93 300E w/ 3.2
85 300D-
79 300SD
82 300CD
83 300CD - CA
87 190E 5 spd
87 Porsche 924S

"..I'll take a simple "C" to "G" and feel brand new about it..."

Are you serious? I'm not driving around with the emergency brake on!!!!
I'm actually looking for some helpful advice - would that it were so simple....

I am having the same problem with my 1980 300D.
In my case I am very carefully following all the archive advice
regarding throttle linkage settings and vacuum issues.

You are probably doing the same. But I know what you are talking about.

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80 300D 340K Owned 30 yrs
83 300SD 440K Owned 9 yrs - Daily Driver 150mi/day
02 Z71 Suburban 117,000
15 Toyota Prius 2600 miles
00 Harley Sportster 24k
09 Yamaha R6
03 Ninja 250

i bet your fuel filter is clogged. i had the same issue while driving to california. i was doing fine on the highway, then after some time i noticed how it would slow down on hills. then later it got so bad, that cruise control could not even keep it above 45 mph. i got off the next exit, and almost kicked mylself for not thinking of it earlier. i replaced the fuel filter (took me less than 10 mins) and was driving 85mph after that.

go and replace that filter...

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Grey '91 350SDL 214k Dad's car
Beige '81 240D 4 Speed 254k SOLD
Blue '82 300D 225k SOLD
White '95 E300D 46k SOLD
Blue '87 190D 2.5 Turbo 315k SOLD
Brown '80 240D 4 Speed 716k SOLD
Beige '80 300D N/A 119k SOLD
Blue '85 300D Model 186k T-Boned

I am new to mercedes and am not familiar with throttle linkage or vacuum system specifics. I know that the AC doesn't work and that it may have to do with the vacuum system - could this be effecting acceleration? Someone suggested fuel filters...?
Thanks

Thanks for the fuel filter advice! I'll definitely try it!

I had the same problem with my 300SD when I got it. There is a little unit
on the driver side of the firewall. It has two lines coming from it. One goes to
injection pump on the side of the engine, and the other goes to your intake
manifold. It also has a two wire going to it. Mine had one of the lines cracked.
I fixed the line, and works perfect now. My friend drove his 300CD for 4 years
without this unit working. It was slow as my ass...So I took mine off and put
it on his. He was shocked at how much faster it was. He was pissed that
he drove it for so long like that. You should feel the turbo kick in at 2200-
2500 RPM. Also you should check the kick down cable. The adjuster is on top
of the valve cover. I set mine this way. I move the linkage to full throttle,
then move the exposed cable left and right. There should be about half an
inch play from side to side. This worked good for me but you might need it
a little looser. If it will not shift, it is too tight. If it does not kick down when
you floor it, it is too loose. Hope this helps.

i agree, its probably a fuel filter and its one of the easiest things to check/replace. if you just bought the car and dont know when the last time it was changed i would recommend a diesel purge (to clean out the injectors) then changing out the 2 fuel filters afterwards. you might also want to check out your air filter they get clogged w oil blow by. if youre not familiar w doing a purge theres plenty of information on this board. Diesel Giant has a great step by step pictorial on his website. good luck!

Here are the steps that I followed. It only got peppy when I finished the list.

Replace all filters, including the one in the fuel tank.
Replaced injectors
Set injection pump timing
Ensure valves are adjusted properly

It's not a rocket, but going up a long steep grade, it will maintain 55 mph or so. On the flat, top speed used to be 70 or so. Now I can do 85 with out the pedal to the metal.

One more thing,,, get a good running start and as one smart guy once said,,, drive it like you stole it.

JCD

I was kidding. It was late and I knew that there would be all the correct advice coming to you soon. Let us know how it turns out after the filters and get good ones not the orange kind, Hengst or Mann; Wixx if you have to. Shop at Fastlane on this site. It supports the forum site. Phil is sort of helpful. And post some pics once you clean it up.

btw You may have to clean out your fuel tank screen. Pretty easy fun thing to do. And when you buy fuel filters get back ups since you should ALWAYS have a spare set and tools in your trunk.
aa

(-:

__________________
'87 924S
'81 280SEL

Sold ->

81 300SD -
93 300E w/ 3.2
85 300D-
79 300SD
82 300CD
83 300CD - CA
87 190E 5 spd
87 Porsche 924S

"..I'll take a simple "C" to "G" and feel brand new about it..."

I would suggest you get the clear plastic prefilter. Especially since you want to run biodiesel. Having a clear one lets you see whats in the filter and when it needs to be replaced. Good luck and enjoy your new adventure.
Try looking at the online shop manuals too. skinnerbox
What are you going to do with the TDI?

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go up a few hills starting from a standstill with shift lever in low. Get a feel for how the engine sounds at a given speed. Sometimes, slowness is a result of the transmission being in a higher gear and this is not always readily apparent.

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'82 300SD - 361K mi - "Blue"

"Good judgement comes from experience. Experience comes from bad judgement."

listen, look, .........and duck.

is always the fuel filter. this is most likely your problem. remember there are two to change. after changing them you will need to use the prime pump to get the air out. if that fails you can remove the air cleaner and spray wd40 right into the intake. the car will run on the spray til the fuel line is purged of air.

if you find a lot of black dots in the small fuel filter you have fungus in the tank. this will require a few doses of fungicide for diesel fuel buyable at truck tractor and marine suppliers.

good luck

benz diesels are the best!

tom w

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.