PeachParts Mercedes-Benz Forum - 83 300sd really slow/no power

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83 300sd really slow/no power

Hi, I checked old posts but I can't find anything about my problem.

My 300sd has become a real dog lately. When I take off the engine seems to stay at 2k rpm untill about 30mph. then the rpms start to increase. then it begin to accelerate pretty good. I noticed that I have to down shift to 3rd to even go slighty uphill and even then I only go 45mph. the rpms only go upto 3k. and to go above 50mph I have to have the pedal completely on the floor. I unhooked the kickdown switch because the car would surge and lose speed when it downshifted. It almost feels like somthing is holding the engine back.

Things I already did was change the filters(fuel/tranny/air), did a valve adjustment, checked boost(11psi), removed the alda, adjusted throttle linkage, cleaned fuel tank/screen, put in lower milage injectors that sprayed and popped right.

Did you do a compression check and/or see if the oil cap dances? That is probably where i would start.

I'd check the lift pump output and fuel pressure.

I did the oil cap test and it dances a little bit but not alot. I haven't done a compression test on the engine yet. does anybody have a article on how to check the fuel pressure and liftpump output? I have both the chilton and haynes books. and they don't have anything on fuelpressure and output

This sounds more like a boost issue. Where did you check the pressure?

I checked the boost on the port on the back intake manifold.

Quote:

Originally Posted by SD Blue (Post 2391758)

This sounds more like a boost issue. Where did you check the pressure?

Advance the set screw 3/4 turn, and it'll run like a different car. That's all mine needed to run like a champ.

Quote:

Originally Posted by MattW (Post 2391774)

I checked the boost on the port on the back intake manifold.

Try at the alda because when I had problems with this it was a combination of cracked flex fittings on the bottom of the boost overpressure valve (on the firewall) and cracked pressure lines.

Not to sound rude but how would I check the boost at the alda if its not on the injection pump anymore?

Quote:

Originally Posted by Skid Row Joe (Post 2391776)

That's all mine needed to run like a champ.

Thats because all you did was hide the cause.

Skid Row Joe,
I see you too have received a spray of venom from the site Idiot. I think we need an ignore function on here.
I have always found your input to be useful and helpful, please ignore the Idiot.

INAPPROPRIATE
B.C.

Quote:

Originally Posted by layback40 (Post 2391933)

please ignore the Idiot.

I sure will, you've been added to my list.

Do you get a lot of black smoke when you floor it from a stop? If not you might have fuel delivery issues. Nobody kinked the fuel injector hard lines, right?

I removed my ALDA and increased boost to 13psi on my 300SD and it was a different car. Since you have already removed the ALDA you should be able to generate smoke at will :)

I would remove the air cleaner and the U pipe and check the turbo for tightness when you spin it by hand. It should move freely.

How is the exhaust system? Make sure you do not have any obstructions.

I smacked my center muffler with a hammer and the amount of carbon it blew out was amazing!

Also look up adjusting the Bowden cable. I set mine to shift at 3500RPM on the SD

Quote:

Originally Posted by MattW (Post 2391634)

Hi, I checked old posts but I can't find anything about my problem.

My 300SD has become a real dog lately.
When I take off the engine seems to stay at 2k rpm until about 30mph. then the RPM's start to increase, then it begin to accelerate pretty good.
I noticed that I have to down shift to 3rd to even go slightly uphill and even then I only go 45mph, the RPM's only go up to 3k.
To go above 50mph I have to have the pedal completely on the floor.
I unhooked the kick-down switch because the car would surge and lose speed when it downshifted.
It almost feels like something is holding the engine back.

Things I already did was change the filters(fuel/tranny/air), did a valve adjustment, checked boost(11psi), removed the ALDA, adjusted throttle linkage, cleaned fuel tank/screen, put in lower mileage injectors that sprayed and popped right.

* Re-install the ALDA.
* Check and adjust the injection pump linkage to the full throw stop, with a helper holding the pedal on the floor.
* Re-check the valve adjustment.
* Rebuild the lift pump.
* Install the new style primer pump.
* Replace the O-rings on the fuel filter bolt.
* Stretch the injection bypass valve spring to a rest length of 27 MM.
* Jack the car up, and check for dragging brake calipers.

Post a video of the engine (hood open); idle, quick hard acceleration, steady 2000 RPM.

you checked the tranny oil level yet?