87 300D Lacks High Performance
 

I like my new used 87 300D.(220K) I finished rebuilding the Front End and replacing those problematic control arm rear bushings.
My only question is where is the Car's TOP END? Its fine off the line, but theres nothing above 70 mph with the Gas pedal all the way in. I can't feel any Turbo Kick.
Because its fine off the Line, I dont think its an injector issue.
I've heard that this car is supposed to hold a 100 easy. Obviously I got some work cut out for me.

Both filters are replaced
 

I am thinking in terms of the Turbocharger controls..I dont know if the W124 has the banjo fitting issue the W123 had, where the banjo at the intake rear gets clogged and makes the W123 anemic....

Poor performance...
 

You need to read the posts on the ALDA for the injection pump. If you do not feel a surge at around 23-2500 RPM, check the ALDA pressure line to see if it is either broken or stopped up. If it is OK,
then you need some help on the ALDA. Look down the posts until you find info on this problem, the solution is there.

gnashd--thanks--
 

Thanks, I just saw something on ALLDATA, under the Tech service Bulletins that said the same thing...

My 1987 300 TD has a non functional turbo because the waist gate is seized open!

Even so, I can still achieve 110 mph, easy. without any problem.

I get 31.5 mpg.

While I'm aware that I coluld generate more HP, my 603, has enough, more than enough power to drive daily in any situation!

One of these day's, I'll fix the turbo!


You have a fault within your fuel system!

If, when the accelerator pedal is fully depressed, the lever on the injection pump goes to it's limit, then the problem isn't the linkage, but is almost surely that there is not boost pressure from the intake manifold reaching the fuel enrichment device (ALDA) located on top of the injection pump. This is USUALLY a simple fix. Simply clean out the line from the ALDA thru the switchover valve (be sure the vlave isn't plugged) to the intake manifold and the manifold fitting.

0-62 mph acceleratio time should be about 11 sec. If it more like 15+ seconds, then it's likely there is NO fuel enrichment as that cuts available power back from 148 to about 109 hp.

Marshall

Thanks!!
 

thanks Mr Booth, that was a very helpful answer....

Yes - please post your 0-60 time on a flat road (stopwatch works great), and also if possible test the boost pressure (while driving!) with a "T" fitting at the ALDA.

A properly tuned turbo will never "kick in", there will be strong power off idle, smoothly building to the redline. A "kick" means a lack of off-idle power, what you're feeling is the fuel enrichment when the turbo spools and ALDA adds fuel. That means things need adjustment...!

:)

I found a possible solution to the problem tonight
 

One of the rubber fittings on a white plastic Line coming from the ALDA to a component ( a black vacuum switch with 2 vacuum ports) on the driver side inside fender was ripped right in two and the white plastic line was off and sitting there dangling. The second line is intact.
I wont know until tomorrow when I fix and test it.

THANKS everybody!!!!!

Yup - that sounds like the pressure line from the intake to the ALDA. If that line is ruptured, you're never getting fuel enrichment. However the car should be pretty snappy with that line broken, unless the ALDA needs tweaking... please test 0-60 times anyway if possible! I think you might need a little adjustment even after the plumbing fix.

:)

I will test it this Afternoon after work!
 

Whew, in the beginning the W124 87 300D was a little intimidating!
I mean the vacuum door lock system works by an electric signal from the master door switch increasing vacuum--compared to that the W123 is like a VW Bug. The AC sytem has a control interaction with the serpentine belt....
The service CD looks a lot more involved than the W123. For a while I almost regretted buying the car~~~ I sure am glad there are people out there who know this Car

The car is snappier...
 

The car is snappier...but I also found at least 4 vacuum leaks / dangling lines, one was at the Transmission amplifier, and another was a Thick Black Line running to a Filter like element right behind the driver headlight.
I have a feeling the Transmission Modulator at the transmission also has a Leak but I couldnt go under the car, I got home Late.
I didn't want to take it to max capacity on the Highway until tommorow. I still suspect its under performing..but because the Car is very Badly aligned after a complete Front End rebuild and pulls to the Right.
I'm taking it into get it aligned tomorrow at 8 am. I will do some highway testing after that.

The more you work on the car, the less intimidating it will become - trust me. It's not really more difficult than a W123, there are just more items on the car. I used to be a little intimidated myself but I'm not anymore, at least for most things (don't think I'm ready to rebuild the transmission myself, for example!)

You definitely don't want any leaks in the tubes for the transmission circuit, ditto for the "blue flying saucer" (actually a vacuum modulator for the tranny). These lines can have either vaccum OR boost pressure, and leaks in any of them can make things not work properly. I replaced ALL my tubes and rubber fittings, they were all brittle and in bad shape after 15+ years. The parts are cheap but it takes a few hours. ;)

The "thick black line" is a vacuum vent, it won't make anything not work if it's not connected. I removed all the junk behind the passenger headlight, it just controls the EGR and ARV, both of which I'd recommend to disable (see photos below).

I removed all this junk:
http://www.meimann.com/images/merced..._solenoids.jpg


I initially capped off the source lines like this:
http://www.meimann.com/images/merced...es_plugged.jpg

I later made it neater by removing the thick black line entirely, and capping it next to the brake booster, and replacing the 4-way fitting with this 2-way:
http://www.meimann.com/images/merced...ac_fitting.jpg


The less junk you have under the hood, the easier it is to work on, IMO...!


:cool:

Thanks GXSR
 

Thanks for your Help, I saved those pictures.
I was worried there was only a W123 community and not any W124 300D devotees on Mercedes Shop. After all, I think they only have this configuration 300D for 3 years, 87-89
Its kind of funny , I didnt even know this car ( A 6 Cyl Turbodieselexisted until very recently. I 've heard that it can do a 100 steady with no strain. The few times I've driven it, I've noticed its a different car than the W123, even in its unmaintained form. (Before I rebuilt the Front End, it would "shudder" under certain Road Conditions because of the old style Front Control Arm Rear Bushings.)

Unfortunately, the more I appreciate it, the more I put the Carpool miles on my 85 W123 and the more I try to "save" my W124 for better trips .I never imagined I would own a 43000 Benz( albeit I paid 2000 for it)

Don't worry, there are a number of us W124 nuts out here. ;) The W123 devotees are more numerous but that doesn't bother us, we know the 124 is better! (j/k, all you 123 folks...!) And the 6-cyl turbo was only imported to the USA for one year - 1987 only. There were about 2500 sedans and 1500 wagons, I think? Or something like that - very low numbers. It will cruise all day long at 100mph (that's 4000rpm) and still get 28-30mpg, believe it or not. Can't do that with a (stock) 123! The 124 feels totally stable at high speeds, which is really nice. If you paid $2k for a fairly clean one, you got a great deal.

:)