300D fuel economy questions

#1

I just purchased an 80 300D and it purrs but my mileage is worse than I was
getting on my 300SD.

There is no particular smoking problem, it starts easily but I am only
getting 22MPG on the highway while holding steady at 65.

I was expecting closer to 30 MPG.

Any suggestions?
--

Roger Shoaf

About the time I had mastered getting the toothpaste back in the tube, then
they come up with this striped stuff.

#2

Roger Shoaf wrote:

Quote:

I just purchased an 80 300D and it purrs but my mileage is worse than I was
getting on my 300SD.

There is no particular smoking problem, it starts easily but I am only
getting 22MPG on the highway while holding steady at 65.

I was expecting closer to 30 MPG.

Any suggestions?

I feel your pain. I was expecting ~31mpg on my '92
300D but I average 26. If I don't use a cetane
booster it gets worse, as low as 23. I run 17"
wheels with 225/45 tires which probably have
higher rolling resistance than the stock 15" but I
keep the tire prx a skosh high.

#3

Roger Shoaf schrieb:

Quote:

I just purchased an 80 300D and it purrs but my mileage is worse than I was
getting on my 300SD.

There is no particular smoking problem, it starts easily but I am only
getting 22MPG on the highway while holding steady at 65.

I was expecting closer to 30 MPG.

The mileage for the 300D is given 8-12 l/100km or inverse 8-12 km/l.
This makes 18-26 mpg.

MB mileage for all older types decreases sharply at speeds exceeding
90km/h or 56 miles/h thanks to the cubic increase of wind resistance
with speed.

You really see the difference at the pump, if you try maximum speed with
a medium strong wind from front or back.

Another important topic is the light gas foot. You can improve mileage
by 10% if you accelerate really slowly in the highest possible gear.
After reaching travelling speed reduce the gas to find the point where
deaccelerating starts.

--

Roland Franzius

#4

On Nov 7, 12:54*pm, "Roger Shoaf" <sh... (AT) nospamsyix (DOT) com> wrote:

Quote:

I just purchased an 80 300D and it purrs but my mileage is worse than I was
getting on my 300SD.

There is no particular smoking problem, it starts easily but I am only
getting 22MPG on the highway while holding steady at 65.

I was expecting closer to 30 MPG.

Any suggestions?
--

Roger Shoaf

About the time I had mastered getting the toothpaste back in the tube, then
they come up with this striped stuff.

My 300SD will get 27mpg at 65 IF i drive it easily. It drops like a
stone to 24-25 when I kick it over 70. Ever notice when you put on the
CC the accelerator seems to come up--almost like you are using too
much foot to go the same speed? This may seem a little odd, but one of
the things I run up against is my car is so quiet, I'm up to 80 mph
before I know it. One of the regulars here gives the good advice to ck
that the banjo fitting at the back of the valve cover isn't clogged.
Ck that. Notice if you are going faster than you think since it's easy
in these cars (My car's spedo says exactly what my GPS reads for
speed. How is yours?). The ups and downs in speed kills mileage fast.
It's worth getting CC fixed (if broken) for the gas savings you get
with fewer radical changes in speed (on a flat road with light traffic
at a reasonable speed). I know this sounds sophomoric, but ck the air
filter, tire pressure, and for fuel leaks (the banjo bolt on top of
the fuel filter housing is a bitch. DO NOT over tighten it). Let us
know if you find anything that helps.

#5

I think something is wrong with your car. You should check your
injection pump, and the chassis alignment. The engine compression
should be good also. The car should give 32 mpg as the catalog says.

Good luck.

On Nov 7, 6:21*pm, JD wrote:

Quote:

Roger Shoaf wrote:
I just purchased an 80 300D and it purrs but my mileage is worse than Iwas
getting on my 300SD.

There is no particular smoking problem, it starts easily but I am only
getting 22MPG on the highway while holding steady at 65.

I was expecting closer to 30 MPG.

Any suggestions?

I feel your pain. I was expecting ~31mpg on my '92
300D but I average 26. If I don't use a cetane
booster it gets worse, as low as 23. I run 17"
wheels with 225/45 tires which probably have
higher rolling resistance than the stock 15" but I
keep the tire prx a skosh high.

#6

On Nov 8, 1:04*pm, My Oregon Shop <35mmproject... (AT) gmail (DOT) com> wrote:

Quote:

On Nov 7, 12:54*pm, "Roger Shoaf" <sh... (AT) nospamsyix (DOT) com> wrote:

I just purchased an 80 300D and it purrs but my mileage is worse than Iwas
getting on my 300SD.

There is no particular smoking problem, it starts easily but I am only
getting 22MPG on the highway while holding steady at 65.

I was expecting closer to 30 MPG.

Any suggestions?
--

Roger Shoaf

About the time I had mastered getting the toothpaste back in the tube, then
they come up with this striped stuff.

My 300SD will get 27mpg at 65 IF i drive it easily. It drops like a
stone to 24-25 when I kick it over 70. Ever notice when you put on the
CC the accelerator seems to come up--almost like you are using too
much foot to go the same speed? This may seem a little odd, but one of
the things I run up against is my car is so quiet, I'm up to 80 mph
before I know it. One of the regulars here gives the good advice to ck
that the banjo fitting at the back of the valve cover isn't clogged.
Ck that. Notice if you are going faster than you think since it's easy
in these cars (My car's spedo says exactly what my GPS reads for
speed. How is yours?). The ups and downs in speed kills mileage fast.
It's worth getting CC fixed (if broken) for the gas savings you get
with fewer radical changes in speed (on a flat road with light traffic
at a reasonable speed). I know this sounds sophomoric, but ck the air
filter, tire pressure, and for fuel leaks (the banjo bolt on top of
the fuel filter housing is a bitch. DO NOT over tighten it). Let us
know if you find anything that helps.

How many miles on the injectors? If it's 125K or more the nozzles
are due for replaement and that could be a factor.

#7

Banjo bolt is the first thing I would check. Fuel filter needs to be
changed... Compression checked if possible.

#8

"Tiger" <tiger0002 (AT) hotmail (DOT) com> wrote

Quote:

Banjo bolt is the first thing I would check. Fuel filter needs to be
changed... Compression checked if possible.

Isn't the banjo bolt only on the turbo models?

--

Roger Shoaf

About the time I had mastered getting the toothpaste back in the tube, then
they come up with this striped stuff.

#9

"Tiger" <tiger0002 (AT) hotmail (DOT) com> wrote

Quote:

Yours is not a turbo?

No turbo, hence my disappointment with 22MPG. I figured I would be getting
something for having a lot less HP.

The car starts and drives nice, no smoke and hums along just fine once you
are up to cruising speed.

--

Roger Shoaf

About the time I had mastered getting the toothpaste back in the tube, then
they come up with this striped stuff.

#10

If the engine runs good then I would do a couple of test... simple stuff...

If you put diesel fuel injector cleaner through the tank, does the fuel
mileage increase? It should...

Tire pressure?

Check your brake to make sure it is not binding...

Check wheel bearing in front and make sure it is not hard to spin wheel.

Trans fluid level? I always suspect the high mileage tranny has some slips
that affect the fuel mileage on diesel.

Air filter... is it new?