PeachParts Mercedes-Benz Forum - View Single Post - Poor mileage on my 85 300D--replace Injectors or IP?

Apotheoun · #15 11-16-2006, 01:00 AM

Quote:

Originally Posted by Brian Carlton

Firstly, the winter fuel has definitely arrived and both the SD and SDL just got severely whacked on mileage. The SD has dropped into the 26's and, last night, I put 10 gallons in the SDL and it got 25.5. The guage was moving down so fast that I was dumbfounded.

So, nobody here in the NE is going to get anwhere near 30 until next spring.

With regard to the IP, I'd seriously doubt that that's your issue unless you've got a horrible idle and one plunger on the IP is non-functional.

Injectors can be a contributor, but, if one injector is not firing correctly, the fuel economy might drop 5% or so. It's not going to be the major source of the problem........if.........in fact it is a single problem.

I'd be more inclined to suspect IP timing. This procedure is fraught with risk in terms of getting it where it needs to be without error. The engine will idle perfectly smooth and will drive OK, but a little sluggish, but the fuel economy will be terrible.

What's it feel like below 2000 rpm? Perky.........or a bit doggy?

The SD picks itself up and goes.........I rarely need more than 2000 rpm.........except for the 3-4 shift when accelerating up to 55-65 mph.

This is such an interesting discussion I can relate to, concerning my newly acquired 300SDS. The economy seems really really bad, and has taken that winterdiesel plunge, and then some! By the odometer, I am getting 15.9 MPG in mixed driving. The best correction scenario might yield 18 MPG, by adjusting for odometer error! Bear in mind this is a stick-shift variant, which one would think should help the economy. The engine seems to run well but makes excessive black smoke; no car tailing me will dare to get close. The RPMs are unusable below 2000 RPM in any gear above first. Well, I can go a lttle below 2000 in second too.

So what engine ailments am I facing? Injectors? Injection timing? Valve timing? Timing chain stretch? Alda? (What is the Alda?) The five cylinder turbodiesel is all new to my experience. As a newby, any insights will be appreciated. Thanks in advance!

Garth