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.
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.
On Nov 7, 6:21 pm, JD wrote:
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.
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.
About the time I had mastered getting the toothpaste back in the tube, then
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...
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?
My 87, though a different engine, recently got 34mpg from Columbus to
D.C., and it has > 222K on it.
Since arriving in DC I have given it a purge, though not by my intent.
(I stupidly put gas in the tank and had to siphon it out, refill and
run the gas out of the system.)
Since then it sounds much better and has a great deal more power.
I might suggest on an older engine that you give it a good cleaning
out, though by the recommended means.
Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here.
All logos and trade names are the property of their respective owners.