PeachParts Mercedes-Benz Forum - Why is my brother's '83 300d so slow?

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Why is my brother's '83 300d so slow?

Hi everyone,

Been a long time since I've posted anything. I drive an '85 300D. My brother liked mine so much that he decided to get one for himself. He bought an '83 300D. I was just able to see it and drive it for the first time today. When I got in to drive it, the first thing I noticed was that it is soooooooo slooooooooooow in the pickup compared to mine. Like a pretty good bit. I also noticed that his speedometer only goes up to 85 or 90 mph where mine goes up to 120 I think. I was under the impression that our cars would have had the exact same engine in them.... Is this not the case? If they are indeed the exact same engines, why would his be so freaking slow on take-off? Thanks!

There are many things that could cause slow acceleration. Take the banjo bolts off the intake manifold and top of the injection pump and clean them. Then get full of carbon and it kills the turbo boost. There could also be a dragging caliper or two, or the parking brake isn't releasing like it's supposed to. Or the linkages could be stiff and need lube, or they might be loosing so of the throw due to worn or broken pivot points. Look at each linkage and pivot and make sure you're not loosing any motion anywhere.

Quote:

Originally Posted by mbinnashville (Post 2529410)

AND YOUR BOOK REPORT IS DUE ON MONDAY....:eek:

Check out the rubber thingy on the firewall, never can remember it's name...

- Peter.

First thing to check when a diesel is not performing is filters. If any question about fuel quality or bacterial action use a biocide to clean out the tank.

On an 83 it is possible it could be taking off in second gear. If they do this it is excruciating.

Holy Cow Roy, talk about inundation!!!! Great stuff there.

I would start by checking the throttle linkage. Have someone sit in the car and push the accelerator pedal to the floor while you watch the linkage under the hood. Look at the linkage at the back of the injection pump and be sure the little arm on the back of the pump is hitting the stop bolt. If it is not hitting the bolt at WOT, you need to figure out why. It could be that the linkage is just worn an has never been adjusted or the throttle bushing/bellcrank on the firewall could be worn. The linkage could also be hooked up wrong if some shade tree mechanic has worked on the car recently.

After you have done this.... Then go on to inspecting the boost lines, cleaning banjo bolts, replacing filters, etc....

Quote:

Originally Posted by pj67coll (Post 2529616)

Check out the rubber thingy on the firewall, never can remember it's name...

- Peter.

It's called the throttle bushing. And it looks like this. Lots of time the rubber breaks and you loose most or all of the motion of the go pedal.

and even in perfect tune, your 85 is not the same as the 83. the 85 has more HP and a newer a/c system. also it has a taller gear ratio, so, you will be turning lower RPM's as he will at the same speed.