Mercedes-Benz Forum banner

1 - 14 of 14 Posts

·
Registered
1981 300cd, 1981 300sd
Joined
·
53 Posts
Discussion Starter #1
Weird Problem. 82' 300d Turbo, Auto, 250k miles, SUPER slow on acceleration. I mean super slow. So slow, I can get out and run faster than it pulls out in drive. I takes forever to get the RPMS up but when I hear the turbo spool up, I feel it pulling and I can get to 60-90+mph no probs after that. But if I stop at a red light, or worse yet, a red light on a hill, I'm not going ANYWHERE. Seems like its starving for fuel, but if that was the case, I wouldn't be able to get to 90mph like I can. If I use 1st to start off, its a HAIR better, but still very slow to get to going. There's basically NO bottom end power at all. So what's the culprit? I was think a bad Vac Mod on the tranny so while it's in D, it skips 2nd and 3rd. adn just tried to drive in 4th all the time, thus the no accel and power. But manually shifting into Low doesn't help too much either. It shifts good, so I'm thinking the trans is good. Turbo works. I also thought about a clogged banjo bolf, but that was cleaned at the exhaust manifold. Maybe the ALDA was messed with and set wrong? Maybe the overboost not working??? Thanks in advance.
 

·
Registered
77 240d, 02 Ford F250 V10 (7mpg), 05 GMC Denali (The Baby Hauler), 2000 BMW 323CI (was my Bros car)
Joined
·
817 Posts
I would try cleaning the banjos that go to the alda and the back of the intake. Also, check your air cleaner. I would check those before you start messing with adjustments.
Jon
 

·
Registered
300SD
Joined
·
11,191 Posts
Also, adjust the transmission shift cable so that the engine will rev up to about 3500-4000 RPM before shifting from the 1st to 2nd and 2nd to 3rd upon hard acceleration.

You may have a bad overboost sensor sending the signal to the ALDA that the engine is being overboosted while it is not, thus severely limiting the fuel flow.
 

·
Registered
1982 300CD
Joined
·
5,140 Posts
A faulty overboost would vent the pressure line to the ALDA, and he would never feel the boost kick in. Added pressure without added fuel does no good.

Bowden cable might help, but it isn't the sourse of his problems.
EDIT: Oops, sorry. It's hard to decypher, I thought he was saying IF it skipped 2 & 3.

Hey I know, maybe your wheels are too small. ;)
 

·
Registered
Joined
·
17 Posts
it skips 2nd and 3rd. adn just tried to drive in 4th all the time, thus the no accel and power.
Have you checked that your bowden cable is attached and on the correct side of the throttle linkage? My car exhibited the same issues when I test drove it, noticed the bowden cable wasn't attached but used it to bargain the price down due to a "slipping transmission".
 

·
Registered
money pits of various forms
Joined
·
5,885 Posts
Start with your linkage, make sure its hitting the idle stop(move the linkage and look on the back of the IP next to the engine).
 

·
Registered
77 240d, 02 Ford F250 V10 (7mpg), 05 GMC Denali (The Baby Hauler), 2000 BMW 323CI (was my Bros car)
Joined
·
817 Posts
You also need to ask yourself, "when did this problem start to happen? Was anything messed with prior to the problem or did it just start happening?"
I have noticed on cars that have turbos that when the turbo isn't spooling the car is slower than a car of the same model with out a turbo. The dead turbo turns into a restriction.
I also agree with winmutt. Make sure your throttle linkage is getting its full range of movement.
 

·
Registered
1981 300cd, 1981 300sd
Joined
·
53 Posts
Discussion Starter #10
I've cleaned the Banjos myself. I just got the car from some so-called Veggie mechanic, but IMHO doesn't know w123's. The ALDA was messed with, that i know. The alda housing was stripped so the screw is hard to adjust. I DO feel pressure coming out of the screw hole when the screw is out so does this go back to the boost control? It felt a little better when I screwed the alda ccw, but is still way too slow off the line to drive safely, meaning- if i'm at a red light on a hill i won't go anywhere when it turns green. The PO said the tank screen was cleaned and filters were replaced, but who knows. I'd hate to go do all that for nothing. I was hoping it would be an easy fix.
 

·
Registered
77 240d, 02 Ford F250 V10 (7mpg), 05 GMC Denali (The Baby Hauler), 2000 BMW 323CI (was my Bros car)
Joined
·
817 Posts
Was veggie run through it? If the fuel system wasn't purged with diesel after runny veggie you might have some build up in there. You might want to try a can of diesel purge. Disconnect the fuel inlet line and the return line and run them directly into the diesel purge can. if there is anything in there it might help clean it out.
 

·
Registered
1982 300CD
Joined
·
5,140 Posts
Here's what I've gathered...

"82' 300d Turbo, 250k miles, SUPER slow on acceleration.
When I hear the turbo spool up, I feel it pulling and I can get to 60-90+mph no probs after that.
While it's in D, it skips 2nd and 3rd. and just tried to drive in 4th all the time
But manually shifting into Low doesn't help too much either.
The ALDA was messed with, that i know."

I know that if you screw the ALDA bolt in all the way, and screwed your bowden cable all the way in (I think in), you can achieve the symptoms you're describing.
My money is on a bad ALDA and bowden cable setting.

Hoping it isn't the IP. Did he mess with the internal settings of the IP, trying his hand at the Superdiesel mods?

Veggie oil can foul your injectors and clog your filters, but you wouldn't get a kick of power after the turbo kicked in.
 
1 - 14 of 14 Posts
Top