Hi everyone,
I have posted to other threads about my poor mileage in my 4-speed 240D, but I wanted to make a fresh thread that details what I have done and then asks for suggestions on what to do next.

My mpg averages about 20.

So far:

I have adjusted my driving style so I shift well below the top end.

Replaced all filters, done diesel purge (snake oil) and have been running B100 pretty regularly for about 8 months.

I have fixed the odometer and I have timed it against highway mile markers and on trips along routes that I know the distance. ODO works just fine.

I have replaced all the fuel lines except for the 2 by the tank. These had been replace at some point by the PO. They show no signs of moisture at all.

I have also replaced the braided fuel return lines. I have not replaced the clear lines.

I have done a valve adjustment and checked it again recently.

I replaced all the soft brake lines and confirmed that the wheels spin freely (no brake binding)

I put a 5* offset key on the timing chain sprocket and adjusted the IP delivery. There is still some slack in the chain so it will need to be replaced

I have not adjusted the spring at the banjo bolt on the engine side of the IP.

I have not repaired some of the worn suspension parts (RH tie rod, LH wheel bearing - I think -, steering damper) that make various noises while I drive.

I have not sent my injectors to Sean to have them refurbed with Monarks.

Blow-by on this engine is really minimal. It never smokes at all. The only time I see anything is at night with a car behind me. Then I see smoke that is heaviest at higher RPMs in 2nd gear. High RPMS in anygear provide some smoke, but 2nd is the smokiest for some reason.

So, especially to those with wizard-like knowledge of diesel engines, what should my priority be?

I don't really want to sink the $1000+ into suspension, a new timing chain, and injectors if this won't solve my mileage problem. I have found myself looking at other Mercedes in the want ads lately, thinking about how nice an automatic 300D with turbo would feel on my commute. Feels a little like cheating

If I was to start making these repairs, which should I start with?

I plan to send the injectors out and have the chain done by an indy I think......
Suspension I will do myself....

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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

I vote for injectors. My mpg's went down over about 12k miles to 28ish and got back up to 34 with the install of new 261 nozzles from Sean. It sounds like your engine is in good shape, but what about your brakes. Do you have any binding? My 240D rolls so well, I have to have the brakes on at the stop light unless it is totally flat.

Also what about tires? Are they up to proper pressure?

Just trying to think of any place you might have excess drag. Its amazing how much it can effect the mpg's.

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1998 Mercedes E300TD

1983 Mercedes 240D Turbo, 131bar injectors, Cosworth intercooler and 63' Ford Falcon radiator, Ardic Parking heater, Headlight wipers, Best 38.6mpg.

1973 Saab 96 Rally Car, 1.8l V4 with all the race bits

Zeke, biodiesel has lower BTUs than D2 and may have something to do with the 20 mpg. What MPG are you getting with D2?

Graminal95, are you really getting 34 mpg? An increase of 7 mpg with new nozzles? If true, that's gonna be my next project!!!

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

How are your tires? Have you check their pressure lately? Probably have but just thought I would ask. Also how is the wear on the tires? You might have an alignment shop check out the alignment.

Also have you ruled out brakes dragging. You could have a caliper seized and a pad is dragging slightly. If your brake hoses are old then can cuase restriction in the system and not allow the pads to release off the rotors like they are supposed to. Brake hoses swell on the inside when they get old. Which allows you to appply the brakes but it doesn't allow the brake fluid to flow back as easily and can cause the pads to drag. You're parking brake could also be dragging. Try adjusting the parking brake off a little and see if that helps.

Biodiesel does have less BTU's but it should only drag down milage a few mpgs, not clear down to 20.

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I ran my 240D 4 speed manual on B99 and it got 33mpg on the freeway at 68mph for 350 mile stretches. I doubt the fuel is the problem.

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1974 240D 3.0L 4(M) - 250K -OM617.910 + 300D FW + Rajay turbo power!
1977 6.9 3(A) - 84k

I would second the injector nozzle's, of all the tweaks and upgrades this yielded the most improvement on MPG's. The roll test also is a great idea.

I do get less MPG's using straight biodiesel I like a 80/20 dino/bio mix.

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1979 Thistle Green 300D 272,xxx miles
1984 Orient Red 300 D 4 spd Euro Import - 189,xxx miles
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Lofat Productions
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Check to be sure your brakes are not dragging, I just found my front passenger brake is on my SD

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1979 240D- 316K miles - VGT Turbo, Intercooler, Stick Shift, Many Other Mods - Daily Driver

1982 300SD - 232K miles - Wife's Daily Driver

1986 560SL - Wife's red speed machine

man, you've been fighting this a long time. With all you've done and the millage still that bad, all I can think of is a fuel leak that only manifests itself while your driving
Did you try parking the car for a while at a fast idle and check underneath after a half hour.

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1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug

"Lifes too short to drive a boring car"

Tire pressure can make 1-2 mpg difference... no small deal.... so try the max pressure listed on the tire for one of your tests... I am sure you know that the pressure must be set when the tires are stone cold... just like the valves...
Have you pulled the precombustion chambers to see that those all important holes and pintle are in good shape ? No matter how perfect the injectors are ( and they should be checked also ) if the fuel is not dispersed properly you can not get good mileage.
Leaving the timing degrees off and then worrying about other stuff does not seem logical... timing of the valves to the crank...and the fuel to the pistons is all important.
I get 24 mpg running on three cylinders... ( 1980 240 manual shift )....

Quote:
"I have fixed the odometer and I have timed it against highway mile markers and on trips along routes that I know the distance. ODO works just fine."

Is it possible the odometer is intermittently slipping and not counting all distances traveled?

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

What size tires are you running?

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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.

Thanks everyone!!!

Shoot - I forgot to mention that I have replaced all the soft brake lines, and confirmed that the brakes are not binding. I edited the OP to reflect that. At one point on my commute, there is a spot with the slightest of grades where traffic backs up. I can creep forward at the speed of traffic by just letting off the brake, so my car seems to roll pretty well.

Re: tires....I am running on tires that are very close to factory spec. Can't remember the actual size now, but they are closer to factory spec than the tires on the 300TD, and it gets a solid 25-30 mpg. I run them at 28 up front and 32 in back. I do check them regularly.

leathermang, haven't checked all the holes (prechamber etc....), I guess that will be something to do while the injectors are out for refitting.

re: timing - I totally agree, but of course I can really only do one thing at a time. I guess if I were to do the timing chain, I could do that while the injectos are out, but frankly changing all the rails and guides has me a bit spooked. - It's not a job I will need to do more than twice (one for the 240 one for the 300TD), so I am thinking I should let experienced hands do it.

funola - I am like 95% sure the odo is working properly. In any case, I mostly just use the car for a 12 mile RT commute to work, so in 4 weeks I go about 240 miles, plus a few errands, which brings me to about 260 miles - at that point I have pretty much used the entire tank (12-14 gallons), so my mpg based on my known driving routes is the same as that calculated off the odo.

Stevo - good suggestion, I will try that tonight and see if I can see any drips anywhere.

mileage is not any different on D2 vs. B100. Maybe 1 mpg lower on B100.

Sounds like the consensus is to get the injectors done.

__________________

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

Thermostat? All my MBs have come to me with bad thermostats... Both of mine are inline for new ones when the weather warms up.
Cars that don't warm up all the way get worse mileage and smoke more.

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Sadly Benz-less

A 12 mile RT commute? That's not very far. I bet its not warming up all the way, so I second the thermostat, but do the injectors too. I just did a set on the 300, MPG's in the low 20's now, hopefully back in the high 20's soon.

My commute is 125 miles RT everyday soo, it has a good amount of time to warm up.

Hope you get you MPG trouble sorted.

__________________
1998 Mercedes E300TD

1983 Mercedes 240D Turbo, 131bar injectors, Cosworth intercooler and 63' Ford Falcon radiator, Ardic Parking heater, Headlight wipers, Best 38.6mpg.

1973 Saab 96 Rally Car, 1.8l V4 with all the race bits

Most days my temp gets to operational temp (just above 80) by the time I get out of my neighborhood (about 1 mile), sometimes it takes another mile or so, but it is definitely warm by the second half of each way, even on our most frigid winter days (30*F or so).

Thermostat is new last year and is MB OEM.

125 mile RT!!?!! I sure hope it's rural with no traffic - I could never do that kind of daily commute!

__________________

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