Bad MPG and slow shifts in 83 240D - PeachParts Mercedes-Benz Forum

Joel1972 · #1 05-19-2006, 06:36 PM

I just bought a 1983 MB 240D and I only got a best of 28 MPG on a road trip. I was driving pretty fast and pushing speeds up to 85 MPH, but it still seems like a bad MPG for a 240D. Does it have something to do with the idle speed control being too low or too high? The car sounds really loud at that speed (80-85 MPH) and feels like it needs a higher gear, is it just geared low?

Also, the car does not want to shift down without manually moving the gearshift from "D" to "S", or from "S" to "L" at really low speeds. From a standing start, it does not feel like it's getting full acceleration and engaging in first gear. It does not slip, but shifts harshly. The downshift button beneath the gas pedal when the pedal is floored does not trigger a downshift either. Any advice?

greasybenz · #2 05-19-2006, 09:46 PM

well it is a 240D. They are the slowest of the diesel bunch. So from what ive read it sounds pretty normal for a 240D automatic. They start off slow or like a old 83 year old man with bad health trying to sprint

as for mpg thats something you should expect driving at 85mph. Also that is pretty good considering the car weighs about 3,000lbs!!!

Car sounds A ok to me, if you wanted something quicker id suggest a 300D turbo.

iNeon · #3 05-19-2006, 10:19 PM

My 240 has never touched 28mpg in the 25k I've driven it. It gets 24mpg like clockwork at 65-70 and I have never questioned it-- It is a nearly full-size car with a weight over 3,300 pounds-- this mileage is fine by me.

Seems uncanny that running your car at its highest attainable speed, that you can beat my 50mph backroads lazy cruising mileage, but, at any rate-- good for your shlomo!

#4 05-19-2006, 10:34 PM

Don't expect 30 mpg at 80 mph, these cars can approach 30 mpg at lower speeds if they are well tuned. You will have to work pretty hard to exceed 30 mpg.

Skippy · #5 05-19-2006, 11:26 PM

Your 240D is getting 28 mpg, and you're complaining?

Mine gets about 24 in commuter use. I drive gently until it's warmed up, then mostly shift at the dots and cruise at "speed limit+5" (40-70) for the 20 mile paved part of my commute. Then it's 6 miles of dirt at 30-55.

Stevo · #6 05-20-2006, 12:37 PM

I agree, 28 MPG is'nt bad considering its an automatic at highway speeds....If I keep it under 60, my MPG is much improved. Congrats on your new ride

t walgamuth · #7 05-20-2006, 02:19 PM

actually if you are showing 28 mpg at eighty with an automatic, your odo is probably slipping!

tom w

iNeon · #8 05-20-2006, 04:05 PM

Quote:

Originally Posted by t walgamuth

actually if you are showing 28 mpg at eighty with an automatic, your odo is probably slipping!

tom w

Exactly. I did not wish to be a gloomy Gus or unkind by saying it, though!

It seems you may not be calculating the correct way?

Fill the tank all the way(which I can't do anymore-- durned 3 dollar fuel heh heh) Drive to your heart's content-- refill the tank *then* do the math. Don't try to do it on a single tank-- you need two full tanks of fuel to do it correctly.

Let us know if your number changes! I would be terribly interested in breaking the 30mpg barrier! I've got the tires overinflated a tiny bit, synthetic oil, new trans service, new filters all around-- and I am *still* at 24mpg. Now that I think about it-- that is sort of low, maybe I am more of this evironmental problem I keep hearing about than I thought!

It really is just a commuter car, maybe an old VW diesel should be tracked down at some point, a cabrio conversion. Who cares if its an ovary on wheels-- a diesel convertible!

#9 05-20-2006, 04:48 PM

Quote:

Originally Posted by iNeon

Let us know if your number changes! I would be terribly interested in breaking the 30mpg barrier! I've got the tires overinflated a tiny bit, synthetic oil, new trans service, new filters all around-- and I am *still* at 24mpg. Now that I think about it-- that is sort of low, maybe I am more of this evironmental problem I keep hearing about than I thought!

24 mpg is low for a 240D. How is you valve adjustment and IP timing?

t walgamuth · #10 05-20-2006, 05:03 PM

oh i dont know, not that bad for an automatic

it is an automatic, right?

tom w

iNeon · #11 05-20-2006, 05:06 PM

The valve adjustment was 2,000 miles ago. IP timing I have no idea, I can't pretend to be a proficient enough wrench to even attempt it-- Unless, of course, there is some sort of idiot proof way of doing it!

I am not at a place where I can afford a repair bill-- so I will have to try and do it with my Fathers help--he runs a crane, I am sure its a diesel-- he does exactly what fred flintstone does, without the brontosaurus!

It has always scared me to futz with the big things, the valve adjustment wasn't terrible, though... but I guess what I am saying is that I'm afraid of making it worse, worse in this case can be read as it being more expensive to run, until eventually, having it repaired by someone qualified.

It has made more sense, to me, to just live with somewhat low economy numbers instead of trying to fix something that isn't all the way broken?

I know I'll face the wrath of all of you more ballsy, "throw money at the car because you want it perfect" über mechanics-- but I don't have money for a full tank at current-- let alone specialized bosch-certified technician type repairs!

I digress-- I'll do a search

**edit**

Yes, it is automatic. Most driving is mixed, a/c on sometimes. I never thought it was bad.. I mean-- the car is 30 years old, rear-drive and kinda heavy. The neon only gets 6-7mpg more and its featherlight fwd 5 speed.

#12 05-20-2006, 05:50 PM

Quote:

Originally Posted by t walgamuth

oh i dont know, not that bad for an automatic

it is an automatic, right?

tom w

I don't think it's terrible, depending how he drives. My 240D auto does a little better (high 20s). I just suspect he could do better if he got everything dialed in perfectly. It's just one of those "pay me know - pay me later" things. It's good that the valves are adjusted, if the IP timing is off a little it shouldn't do any damage. I wouldn't lose any sleep over the difference between 24 and 28 mpg.

t walgamuth · #13 05-21-2006, 08:47 AM

you getting 28 with an automatic?

tom w

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