New Diesel Owner need help, please.

Hello,

I am the very proud owner of an 85 300D-T with 183K. I drove it home from Jacksonville, FL to Fort Walton Beach, FL and it ran very good and strong ( I was running 70-85).

It was blowing the gas monger away on the road and even got a couple of smiles from the big riggers. I am just sold on these cars and their durability and dependability.

I became very discouraged when I check the mileage. I did this twice with fillups and my mileage is only 20 MPG.

What I do know as a rookie is that it idles good (love that diesel purr), starts like a champ (hot or cold), no smoking at idle or highway speeds, and runs about a 90C consistantly. It does seem to shift rather hard and did puff smoke one time when I was following the wife (I suspect she let off throtle and it was wastegate).

The car has had very good maintenance history so I am kinda shocked.

I haven't done anything yet until I get a manual and here from the experts in this group.

I have done some detailed reading and found it could be a bad hand pump (notice diesel come out of it when unscrewed and pumped), maybe need a valve adjustment?, don't suspect IP given the no smoke problem. Suspect injectors maybe?

I need some advice.

I appreciate your help,

Morph (David)

[mreid]

Hand pump will not cause poor milelage unless it has a bad leak. Check valve clearance. If you really were driving at 80mph then 20mpg is not that bad. Drop your speed to 60 and your mileage will go to 30. Not sure what your dif. ratio is but maybe your revs are higher than most. Mileage can be affected by many many variables

Interesting note about hand pump. I had read earlier by Pattsy that a leaking hand pump was droping her MPG to 19.

Yes, I was running that fast and hard back to FWB. Mostly 80-85 with RPM in the 3300 range. This has been explained to be no problem if properly maintained.

Hwy driving is 70min for me else you get blow off the road. I will be doing alot of I-10, I-55 driving to Memphis, TN. I hear that SD owner get 28 doing 75+.

Thanks for the input,

David

I drive my 83 300D between (gasp) 80 and 90 MPH, and then some city driving and still return 21-23MPG.

John

A 123 turbodiesel in good shape will run 90MPH as long as it has fuel, the driver doesn't need a restroom and the cops don't catch you.

In the early nineties I drove my family from Texas to Wisconsin on vacation in my wife's '83 300TD. That thing cruised that long trip as well as ANY car could be expected to do. It saw 90 alot.

Have a great day,

[Ken300D]

If you want to replace your fuel hand pump, I noticed one on EBay this morning:

http://cgi.ebay.com/ebaymotors/aw-cgi/eBayISAPI.dll?ViewItem&item=594774031

This link may not post right, the item number is 594774031.

I am not the seller, know nothing about these, and have no interest in the sale. Just happened to see it and you did mention a possible leaking pump.

That said, it is likely that your fuel mileage would be better at a slower speed like 70mpg. It takes a few more horsepower to push that car through the wind at 85+, and also at those speeds the turbo kicks in pretty well and this results in less mpg.

With the smaller 123 body 300D, I usually get 28 or 29 mpg in combined city/highway driving on my commute.

What I don't have is much in the way of smoke. I've heard people say that their car produces a cloud of black smoke when the turbo kicks in. To me that sounds it would be a problem somewhere - fortunately I have none of that. I wouldn't worry about a puff here and there during driving or even startup. But there shouldn't be a "cloud" following you.....

Do you have a strong smell of diesel fuel under the hood?

Ken

[jcyuhn]

The big mileage problem with the 123 is its aerodynamics. I read its drag coefficient is .42. That's a terrible number - about the same as a pickup truck. As a result, fuel mileage falls off tremendously as speed increases.

The 126 chassis SD actually gets better fuel mileage at highway speeds because it is much more aerodynamic.

That said, 20MPG sounds a bit low. I'd expect a figure in the range 22-23MPG. Check the usual things - valves, cam timing, injection timing, injector pattern, etc.

A good W123 Turbo in top tune will see 100 mph. It can do a little more, but its a GREAT 80 mph car. In fact, I think that's when the car comes into its own, 80-90 mph. Really, its a fast cruiser. Very few cars can keep with a Turbo's stamina and satisfaction at speed.

Don't flame me..



she still had more..

WOW! You are the man... Taking a picture at those speeds! Oh, I believe the car could do more. To be honest, the fastest I've ever gone (noted) was 102 mph... But there was this one time my father, who also had an 85 300 about 10 years ago, he swore he hit 110 in his. I may have gone faster than 105, racing a Jetta VR6. Needless to say, that was the last time he EVER bothered me again on the highway. BTW, what year is your car???

Yep, its my car, she had 199K then, 210K now. She's a 1983 300D aranthrecite grey/palimino.

I took this pic on I-80 between exit 30 and 42 somewhere..

Here's another one to chew on, 87 300SDL 232K then, 243K now. suprizingly the 300SDL just a little more power left that speed than the 300D.



I know i'm crazy..

We have lots in common, mine is also Anthricite over Palomino! I also live near I80, maybe we should meet and elude the cops as to which is which. Or we could pull a "Fast and Furious" (You had to see the movie.)

[Jim Anderson]

I wanna see the tach!

what, you don't belive me?