ok so i seem to be only getting 10miles to the gallon on my 300d
a full tank of gas usually is like 225 miles

things i have replaced

fuel filters
oil filters
new bosch glow plugs
new primer pump

i adjusted the ALDA 1.5 turns

other than that nothing

i have to do valve adjustments soon as weather permits
would this affect mileage that much?

Do you drive a relatively regular route routine or do your trips vary a great deal? I ask because apart from everything else, the odometers in these old cars are notoriously prone to failure, including not registering correctly. Some people who post issues like this find that this is the case... their mileage is fine, but the odometer readings they are using to calculate it are way off.

You cannot be burning that much fuel, even with valves out of adjustment. Sometimes the fuel lines under the car can develop a leak that only evidences itself when the system is working (may not drip when the car is stationary).

First get under the car and see if you can see any evidence of a leak.

If that doesn't work... if you have access to a compressor, run an air line into the filler neck then seal it off as best you can. Pressurizing the system that way should highlight the problem.

__________________


Mac
2002 e320 4matic estate│1985 300d│1980 300td
Previous: 1979 & 1982 & 1983 300sd │ 1982 240d

“Let's take a drive into the middle of nowhere with a packet of Marlboro lights and talk about our lives.” ― Joseph Heller, Catch-22

great idea zacharias.
i will do that..i have acess to alift..ill throw it up on there...
would a dirty gas tank filter do this..havent changed that yet either.

Tank filter has nothing to do with this. Oddly enough, when the fuel filters start to clog and restrict fuel flow, you may see an increase is mileage prior to the onset of running/missing/stalling problems.

In addition to the ideas already offered, look for brake(s) sticking on, bad thermostat not allowing the engine to reach full operating temperature, bad fuel injectors.

Also try switching to another source of diesel fuel.

__________________
Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC

I didn't see air filter mentioned.

Paul

__________________
84 500 SEL (307,xxx miles)

Have you cleaned out the alda line? Check this procedure:

Mercedes ALDA boost system service

The only time my mileage was this low, it was caused by a leaky fuel line. Eyeball the whole system, from tank to injectors.

new thermos stat
alda line cleaned
no air filter in at the moment

Have you checked to make sure that your fuel tank hasn't imploded from too much vacuum? Several people have had that happen before. If you remove the panel in the trunk you should be able to see if it has or not. Also do you ever hear a hissing sound when you remove the fuel cap?

__________________
http://myworld.ebay.com/blacklabelskates/

there is not any hissing..or implosion
good point tho

Well, how much does it take to fill up? Tank capacity is what, 21.5 gals? Surely you aren't running it dry every time. A W123 with worn out injectors and under-inflated tires is perfectly capable of delivering city mileage in the high teens.

__________________
'79 240D

If that much fuel is going through the engine, you will be able to notice a very pungent raw fuel smell in the exhaust. If you notice such a smell after a 10-15 mile drive with the car at idle, you should look into adjusting your timing as you will be too far retarded. Your filters, ALDA, etc should not have much affect at idle if you are still smelling rich exhaust. Your injectors would have to be over pop pressure or extremely worn to see numbers like 10MPG. The most likely cause of your MPG numbers is a fuel leak or invalid calculation. I am no stranger to nailing my 300SD to the floor for any occasion and I see a consistent mid 20's for MPG.

__________________
1991 F250 super-cab 7.3 IDI. (rebuilt by me) Banks Sidewinder turbo, hydroboost brakes, new IP and injectors.
2003 S430 - 107K
1983 300SD - Tanoshii - mostly restored ~400K+.
1983 300SD - Good interior. Engine finally tamed ~250K.
Monark Nozzle Install Video - http://tinyurl.com/ptd2tge

THIS! If you went by what the odometer did, my W114 got something on the order of 0.5 mpg. In actuality it got more like 15. Worst I've seen with a diesel W123 and a known good odometer was 17 one tank in my 240D. It was in the winter with all short trips around town, many cold starts, iffy loop glowplug system, and apparently worn out injectors.

__________________
Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 400,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 22,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.

Fix that. Now. Please. That is never acceptable, for any reason.

__________________


Mac
2002 e320 4matic estate│1985 300d│1980 300td
Previous: 1979 & 1982 & 1983 300sd │ 1982 240d

“Let's take a drive into the middle of nowhere with a packet of Marlboro lights and talk about our lives.” ― Joseph Heller, Catch-22

Absolutely. If you're really using that much fuel, you'll have a trail of black smoke, red hot brakes, or a trail of leaking fuel on the ground.

__________________
'83 300D, 126K miles.

I was getting low mileage and it was my rear brakes dragging.I felt my rim and it was hot.I had to replace calipers.

__________________
1999 w140, quit voting to old, and to old to fight, a god damned veteran