'83 MBZ 300cd

Hello, I bought an old MBZ 1983 300cd that had been in an accident. The front-end needed to be replaced. I changed out the grill, radiator, fan, belts, water pump and housing, thermostat and housing, changed the
fuel filter. I've added oil, and will change that this weekend as well as the transmission filter, gasket and fluid. The car was running Biodiesel at the time of the crash and from what I know of the car it has a rebuilt engine in it that was rebuilt 20k miles ago. The previous owners sold it to me for $500. Once I finished the repairs, I fond that the car ran well, but it is very sluggish starting from a stop. In the beginning, The car was slow all the time from a stop and on hills. I changed the fuel filter and that improved the speed. But it is still slow. I switched from Biodiesel to regular diesel thinking that the Biod was having an effect. The car did speed up a little, but still is slow.
So I am at this point where I'm not sure if I want to proceed with it. I am $1300 in to it and I'm not sure if I am coming up on a money pit or not. I have a friend who is helping me with the car (He is a 20 year owner of 300cd and does all his own work - he owns 3 300cd and 4 other Mercedes models). I went over the transmission with him and we determine that it is shifting smoothly. There is a the first shift is noticeable, but I've been told that it is normal. The car runs well when very warmed up. and has sufficient power after driving for 15 minutes or so on freeways. In the city is a different story. If I am driving surface streets the car never really gains it's power until I get to the freeway (which is a the end of my commute)
I'm stumped at this point. It seems like it is not getting enough fuel as my foot is always on the floor. Any Ideas?
Thanks
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It sounds like if the tranny shifted too early so the powerband was never realized...I believe this tranny is supposed to start of 2nd gear and then onto third and fourth.
I need to ask you... does the tranny stay in third gear long enough or does it kinda shift immediately to last gear? If it does stay in third long enough to a certain RPM like about 2500RPM, then tranny is fine... you just need to adjust the throttle position cable (for the tranny) so that the tranny thinks it is at higher RPM and thus shift later... rather than early.
If the tranny shift immediately into last gear, then you got a tranny problem. It is usually the problem of the valve body... or it can be the servo... but it is a gamble that you might as well swap it out for a rebuilt one... like $1200... I don't think you have this in mind but heck... it would last forever.
You also have friend's car to compare it to... please drive his car to see if it is same as yours...
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I did. His cars (both 300cd currently on the road) are quicker from the start. and have power. granted, I had an acura integra, so I am still used to the car jumping off the line. The car shifts normal. it goes for a while and then shifts. I can't give RPM as the guage is not working. I haven't even thought about that yet. I occasionally will start from S and even L as the lower gears give a little more power earlier. Campared to my friends cars, they both shift at the same time and feel about the same. there is a noticible shift, but nothing alarming. I've had my friend drive it and he feels the same way, shifts at the right places, but is sluggish from the start. Once on the freeway, it goes like a bat out of hell. I feels like I just am not getting fuel in.
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That's a mouthful!
The basic complaint is poor power (and therefore acceleration), particularly when the motor is cold.
Some thoughts and questions (in order of effort and $):
Does the transmission start off in 1st gear? (As the car accelerates can you count 1st, 2nd, 3rd & 4th as it shifts?)
Have you checked that the banjo fitting and its hollow bolt are relatively clean? (Both are located at the very aft end of the engine's intake manifold.)
When you check these, follow that plastic tube to the switchover valve and on to the injection pump (IP), be sure all connections are tight. The point of its termination (on the IP) is the aneroid compensator (ALDA). If you have a 0 - 15 psi pressure gauge you can check this system. AT 4,000 rpm under load (driving) the gauge should indicate about 10 - 12 psi of turbo boost. Without such boost the engine will be flat.
Throttle linkage. Use a flashlight to check whether the IP is getting the full input of the accelerator pedal; by (with engine OFF) flooring the accelerator and holding it while you look BETWEEN the IP and the block to see if the lever attached to the IP is against its full throttle stop. OK if it is, linkage adjustment needed if not.
When were the engine's valves last adjusted? If unknown adjust them; poor compression makes starting hard and cuts acceleration.
Finally, a compression check after the valves are known to be adjusted will indicate the engine's compression. Since diesels are compression engines their compression is key to their performance. This engine's compression will indicate the veracity of the claim that it was rebuilt 20K miles ago, or not. If none of the earlier suggestions cure the problem a compression test will determine if this car is viable (and something else is wrong) or that its motor needs an overhaul.
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snipped-for-privacy@gmail.com wrote:

Did you change both fuel filters (main and prefilter)? Biodiesel has a tendency to "clean" your fuel tank, clogging up the filters.
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