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  #1  
Old 10-01-2008, 10:08 AM
nickofoxford's Avatar
2 doors, 5 cylinders
 
Join Date: Jul 2008
Location: S.E. PA
Posts: 447
240D Mileage...

Hey everyone, what millage can I expect from my auto 1980 240D? I mean this sucker only gets 200-250 miles to a tank.

So a 17.2 gallon tank getting 242 miles equals 14.06xxxxx MPG. I've heard that 30 MPG isn't uncommon for a 240D to get, so whats going wrong here?

Some general background about my 17 year old driving habbits . The last tank I used to "analyze" my mileage was filled all the way to the neck, and ran until I hit reserve. So pretty close to 17 gallons, only 242 miles.. I didn't drive the car "balls to the wall" actually I really fought forcing a downshift but did right after I filled it up . Didn't go over 60 at all and don't drive highway but twice on that tank. Mostly back roads going 30-40 and not mashing the gas to get there.

It has a new air filter, transmission fluid checked and good, tire pressure is 40 all around (I know this is high), Oil is a tad low and very black, coolant system is ok. I can't think of much else to be relevant. Haven't touched the injectors or the IP, new glow plugs btw. A little puff of white smoke at high unloaded RPMS and sometimes at takeoff. Idle pings so Im thinking maybe injectors..

So if you actually read ALL of my blabbing, what do you think? I mean damn near everyhting on the car is original.. I have yet to do the valves or check the timing chain but something simple could be causeing this "poop" mileage. Thanks for reading guys,

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  #2  
Old 10-01-2008, 10:19 AM
zeke's Avatar
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Join Date: Sep 2007
Location: The Alamo City, TEXAS
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That is similar to what I am getting in my manual 240D
I have adjusted the valves - no help
This month I am going to check my timing chain stretch and IP timing.
If that all lines up, I will clean my injectors, and if that doesn't help, I will replace the nozzled then pop test and balance.

Hopefully that will reclaim my lost mpg.

The thing is, that the car is running really well. Minimal blowby, good power and speed, and no smoke except when I look behind me at night (through a car headlight).

I will be watching this thread for other thoughts/suggestions!
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Current Mercedes
1979 maple yellow 240D 4-speed


Gone and fondly remembered:
1980 orient red 240D 4-speed

Gone and NOT fondly remembered:
1982 Chna Blue 300TD

Other car in the stable:
2013 VW Jetta Sportwagen TDI / 6-speed MT
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  #3  
Old 10-01-2008, 10:51 AM
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Join Date: Oct 2004
Location: Northwest, Arkansas
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May seem obvious, but check your odometer. Could be sticking, slipping, or wrong based on tire size.

I fixed my ODO last year, so I can track MPG now. Almost all city driving, mostly below 40, pretty consistent between 23 and 26 MPG, at 5280 feet altitude. Auto trans.

Highway at 55 to 65, have gotten up to 28. Higher speeds start decreasing MPG. I have never been in the 30's, no matter what.

These cars were built when the national speed limit was 55, so that makes a difference as well. EPA MPG when new was something like 24 -33. I am sure the 33 was a manual trans, running right a 55, on a very flat track.......
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2002 E320 Sedan 93K Designo Mocha Black Metallic!
1995 E320 Wagon 205K Black Wagon
1982 240D 183K SloPoke

I believe each of these cars are the final production year for that model.
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  #4  
Old 10-01-2008, 12:01 PM
fruitcakesa's Avatar
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Location: Vermont
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dragging calipers?

If you still have the original rubber brake hoses could they cause the calipers to drag slightly?
They can degrade internally and swell to restrict fluid flow
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  #5  
Old 10-01-2008, 12:09 PM
pawoSD's Avatar
Dieselsüchtiger
 
Join Date: Oct 2004
Location: Grand Rapids, MI
Posts: 15,438
Yep, check:

-Odometer for accuracy
-Brakes
-Injectors
-Timing Chain Stretch
-Fuel return lines on the engine (the fabric wrapped ones between each injector and fuel filter holder)
-Rubber fuel hoses for leaks
-Fuel lines under the car and back at the tank for any leaks or wetness


If your exhaust is not constantly black/gray all the time then you can be assured its probably not injectors or timing chain stretch. Leaks can often go undetected aside from low mpgs....do a thorough check.
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-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)
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  #6  
Old 10-01-2008, 12:34 PM
zeke's Avatar
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Location: The Alamo City, TEXAS
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Quote:
Originally Posted by pawoSD View Post
If your exhaust is not constantly black/gray all the time then you can be assured its probably not injectors or timing chain stretch. Leaks can often go undetected aside from low mpgs....do a thorough check.
I have searched the forums and this is the best statement about how you know when to replace your nozzles or the impact of timing chain stretch I have seen.

What are the symptoms of overdue nozzles, timing chain stretch, and IP timing?

Unburnt fuel in each case?

In my case, I have checked the odo, and replaced all the fuel lines with the exception of the ones under the car (they are completely dry and had been replaced by the PO) and the fuel return lines. These don't look bad, but they are the old braided style, so they could be original. Still, they aren't spraying fuel at any rpm, so it is hard for me to believe that I could lose 8-9 mpg from these lines even in the event that they are weeping (though I don't see it).
__________________

Current Mercedes
1979 maple yellow 240D 4-speed


Gone and fondly remembered:
1980 orient red 240D 4-speed

Gone and NOT fondly remembered:
1982 Chna Blue 300TD

Other car in the stable:
2013 VW Jetta Sportwagen TDI / 6-speed MT
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  #7  
Old 10-01-2008, 01:18 PM
pawoSD's Avatar
Dieselsüchtiger
 
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Location: Grand Rapids, MI
Posts: 15,438
When did the engine last get a valve adjustment? Have the injectors ever been serviced or checked? How many miles on the motor?
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-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)
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  #8  
Old 10-01-2008, 01:48 PM
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Join Date: Oct 2001
Location: around Charlotte NC
Posts: 586
also driving habits

If you do many short trips your mileage will be lower. Diesels do better if warm and running longer distances at contstant speed. My old SDL would get 22 mpg in the summer, with short trips, and with the AC on. Longer trips and no ac would result in 28-30 mpg.
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  #9  
Old 10-01-2008, 01:51 PM
zeke's Avatar
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Location: The Alamo City, TEXAS
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Ok, I don't want to hijack this thread, so I posted my answers to pawoSD's ??s in my earlier thread:

http://www.peachparts.com/shopforum/showpost.php?p=1980711&postcount=19
__________________

Current Mercedes
1979 maple yellow 240D 4-speed


Gone and fondly remembered:
1980 orient red 240D 4-speed

Gone and NOT fondly remembered:
1982 Chna Blue 300TD

Other car in the stable:
2013 VW Jetta Sportwagen TDI / 6-speed MT
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  #10  
Old 10-01-2008, 02:22 PM
nickofoxford's Avatar
2 doors, 5 cylinders
 
Join Date: Jul 2008
Location: S.E. PA
Posts: 447
I will check my odometer today against mile markers on the highway, I guess that is the best way to do it??

The engine is origional, with 170,000 miles. She runs strong, minimal blowby.. so good performance bad mileage I don't get whats going on here .

I don't know if the valves have been done but I doubt the PO did them at all, will do this weekend.

I'll check the brakes I know the rotors are still a little rusty so it could cause a little drag.

Will report back later tonight thanks for all the input so far!
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  #11  
Old 10-01-2008, 02:51 PM
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Nobody regularly runs a 240D in the 30s unless they're selling a car on eBay.
Over 7,500 miles my '83 240D manual trans 4spd averaged 28mpg, one tank hit 32mpg but that was the highest I ever got in 30,000 miles.
Best mileage will be achieved by driving 60-65mph on the highway for hours at a time. Everytime you stop you're losing mileage...

Very common to have a thermostat that doesn't allow your car up to temp which will destroy mileage and carbon up the engine. Temp should be just over 80c indicated.
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  #12  
Old 10-01-2008, 03:02 PM
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Location: Walnut Creek, CA & 1,150 miles S of Key West
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Quote:
Originally Posted by nickofoxford View Post
I will check my odometer today against mile markers on the highway, I guess that is the best way to do it??
GPS, if you have one, would be more accurate.
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N. Calif. & Boca Chica, Panama

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09' Hyundai Santa Fe Diesel 48k (S.A.)
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  #13  
Old 10-01-2008, 03:25 PM
nickofoxford's Avatar
2 doors, 5 cylinders
 
Join Date: Jul 2008
Location: S.E. PA
Posts: 447
Curtludwig,
I don't think going 60 is going to help anything out, these cars have a narrow efficiency range, so 3000RPM @ 60MPH = bad mileage. Maybe on the manual though, I don't know. And I meant average speed, like min + max divided by two. You don't want to be doing 30 through the S turns around here. I do think the thermostat could be stuck open I'll check this later, it does warm up slowly.

TMAllison,
I like the GPS idea. Although, I don't have one . I was thinking about rigging up my bicycle odometer to one of the back tires, It's like the one in this link: http://www.uxcell.com/functions-bicycle-bike-lcd-led-meters-speedomter-odometer-p-4741.html I can calibrate it to the size of my tires and get very accurate data . Will post pictures for you.


I drive it every day to and from school, but it's only a 3 mile drive and it can't suck up that much gas being cold going to school, can it?
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  #14  
Old 10-01-2008, 03:39 PM
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Join Date: Feb 2006
Location: Vancouver, WA
Posts: 68
My manual 240D got about 16-18mpg when I first got her.
After much work for 3 years on my and my brother's part, it's now getting an average 25mpg.
And this is driving a very short trip to work, with longer trips throughout the day to various sites.
I've noticed several things that seem (to me) to make a difference, and I'm new to this really, so forgive any ignorance.
----valve adjustment- definitely brought up the mileage and she runs much better properly adjusted. There are lots of great posts on how to do this here, or you can pay a shop to do it.
----diesel #1=bad mileage. It may be great in the really really cold winter days, but diesel #2 seems to give me an increase average of 3mpg every time.
----driving. If I drive like a moron, I pay for it
----highway miles at 55-60mph on a flat run give me the best mileage
----as always, make sure all filters are clean, she gets proper maintenance and oil changes.
Good luck.
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1977 240D
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  #15  
Old 10-01-2008, 04:05 PM
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Nickofoxford 3000rpm = just over peak HP (which I think is something like 2650 but I forget) so better mileage. Faster than ~65mph and you'll be using so much extra power to overcome wind resistance you'll lose mileage.
Best mileage is definately on the highway, longer runs at 55-65mph. Don't just say I'm wrong do some tests and prove it. I drove a 240D on a 45 mile each way commute for 2 years, when I could managed to keep my speed to 65 on the highway or less my mileage was much better. I never did significant tests at 55mph to see if there was an improvement there, there might be but I couldn't stand it long enough to find out.
The trick to high mileage is to drive long trips, short runs are what bicycles are for

Nicolette is right, you will always lose a couple mpgs from winter fuel. I also found I lost a couple mpgs from snowtires. I see that on my 190D also, I change back to summer tires and mpg goes up immediately.

Its interesting that clogged fuel filters hurt mpg but its true, so does a clogged tank vent. Both of my cars have at some point had clogged tank vents. The 240D is pretty easy to clean, easier than the 190D anyway.

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