check to make sure you still have the plug
in the last leak line.

Are you seeing any signs of leaking after it sits?

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81 Mercedes 300SD 289k.......SOLD
82 Mercedes 300CD 252k......slow ride

82 mercedes 300 SD...mi Unknown
83 Mercedes 300D ????ksniff..gone too
84 Mercedes 300D 148k........SOLD
85 Mercedes 300TD 386k and holding some one elses project

Plug is intact in return lines. Thanks all for helping me id my trunk badges. When I order parts, it says 300d t. And it differentiates my car from a non t. (what a waste of time)
I'll check the sender. Maybe the car has got a stuck sender, but my question was,
Would tired injectors be symptomatic of bad fuel economy? I'm guessing that it won't matter much what model I have. 300 or 240, suffice it to say the car is an 85, and I do have an 85 240 euro also.

The answer to your question is YES injectors can lead to poor fuel efficiency. There are a host of things that can lead to poor mileage though, each contributing a small amount.
Air filter, tires, alignment, valve lash, exhaust restrictions, ect... Without any indication of what the current mileage is, no one knows whether its good bad or otherwise.

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For Sale: 1982 MB 300TD
1995 Chevrolet Suburban 6.5TD

Sold: 1980 IH Scout Traveler- Nissan SD33T Diesel

How does it run? Loud? Smoke? How are the return lines? Any leaks? Smell diesel? Look under the trunk and check to make sure the tank fuel lines aren't seeping.

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http://superturbodiesel.com/images/sig.04.10.jpg
1995 E420 Schwarz
1995 E300 Weiss
#1987 300D Sturmmachine
#1991 300D Nearly Perfect
#1994 E320 Cabriolet
#1995 E320 Touring
#1985 300D Sedan
OBK #42

They'd certianly not help you get good milage, but they shoudln't cause you to burn that much extra fuel. Being able to see it drop means you're going through a lot of fuel in a short amount of time. If you're putting that much extra fuel through the cylinders, you'd probably be laying down a fog bank behind you. In other words, I think you would have noticed by now

Two other possibilities:

The fuel sender unit (or maybe gauge) is lying and not reporting the correct amount in the tank at certain points. Easily verifiable if you fill up when the gauge points at differrent places.

The tank has been collapsed and doesn't hold as much anymore. Easily verifable when you fill up when empty. Since you may not be able to trust the gauge and sender unit, you'd probably have to run it out of fuel before refilling to get an accurate read, a procedure which isn't exactly recommended.

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'83 300DTurbo http://badges.fuelly.com/images/smallsig-us/318559.png

Broadband: more lies faster.

I'm thinking that the tank holds about 16 us gallons. It may be that the fuel sender is hanging and doesn't drop for a while and then drops quickly but I still appear to get less than 20 mpg. No seeping on fuel lines anywhere. No fog of unburnt fuel from the tail pipe.
No horrible diesel smell anywhere. Engine is a diesel sounding, a bit louder than my 85 300 tdt, and about the same as the 240d. I guess I'll adj. the valves, and systematically go about the general tune up. Oil filter is newish. Maybe about 1,000 miles on the oil change.

If you could watch the gauge fall while driving then your range per tank would be like 25 miles.....so I am betting you have a leak or the sender isn't working right.


My dad said back in the day when he drove his dad's brand new 280se that if you floored it on the autobahn you REALLY COULD see the gauge moving. We're talking 6-7mpg at those speeds! It was FAST though. 135mph+ fast....with the fuel moving at a similar rate.

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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)

Humour me, your car has some potential in my opinion. Read Cervans recent post mislabelled rack damper pin. Remove the spring from the injection pump relief valve. Illustrations on how that relief valve is assembled are on that thread.

Pretty simple. Measure the length. If shorter than 26 mm stretch it to that length carefullly. Install it and and post. Cheapest place I can think of to start with some potential. Maybe it's ok maybe not. I cannot give odds yet. Not enough information known.

All of a sudden it may be the best thing to check before going on to more expensive things when fuel milage is substandard and no leaks are evident. Some 123 cars really never improved their fuel milage to normal with a lot of money spent trying. I do not think any member including myself was aware of the importance of that relief valves pressure opening point. Again very easy fix if bad.

In your case consider it a new maintenance item. Should be checked anyways to make sure it is not substandard. It is a spring that has been under constant load since the car was made twenty=thirty years ago. It is very reasonable for some of them to have sagged over the years. Best of all the check is quick, easy and cheap.

Your milage is so poor that even if the spring needs calibration and makes a signifigant improvement. There may be other issues. As of today though not to check this before moving on is not smart when milage is low ... I expect a lot of those springs will be inspected by individuals soon. If they have compressed with age there are several symptoms possible.

In a complex way they retard the running timing of the injection pump and produce other suspected effects depending on how much they have settled. Read his post and give it some thought this approach and paying attention to it. Pretty well brand new.

You could say tests to get a baseline of how large a percentage have the issue with this problem are required. What harm is done? All you are doing if required is restoring the spring to meredes recommended length. Restoring the correct opening range for the injection pump return valve. Not rocket science at all.