I recently purchased a well maintained 1987 300D.
The car is lacking boost/acceleration when starting from a dead stop. Once I have reached 50-60 mph, it accelerates fine.
Any ideas?
It has been well maintained. I am somewhat discouraged.
I have owned several 123 bodystyle diesels, but I am a complete rookie with this vehicle.
Any help would be greatly appreciated!!!

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1985 Mercedes Benz 300TDT, 170,000 miles
1983 Mercedes 300SD, 200,000 miles (sold)
1988 Toyota 4x4 Xtra Cab
2003 Toyota Tacoma
2003 Toyota Landcruiser
1987 Mercedes 300D
1991 BMW 318is

there are a few things you can do, look in the wiki/tech archive. search alda adjustment, egr mod, and diesel purge, to name a few. read any one of these and you'll discover more.

You are not a rookie with diesels so I don't need to tell you that's part of their "charm".

My 1983 300D developed the same symptoms. I found I had worn out the accelerator linkage where it enters the engine compartment from the firewall. I wasn't fully engaging the injection pump. It's about a $50 part new. Fixed the problem. Mine came on gradually and I didn't realize how sluggish it was until I had trouble climbing a steep parking lot ramp from a stop. Replaced the part and it drives better than it has for years.

When I picked up my blue one in LA it had similar problems, and an uphill freeway entrance was a long climb to 60mph.

The Switchover Valve was clogged (search switchover valve) so boost enrichment was not available.

The ALDA was running lean, so even with the cleaned Switchover Valve it developed little off-the-line power and slow turbo spool-up (search ALDA).

The Bowden Cable (or kickdown cable) was adjusted long/loose so the transmission would upshift too early and not allow the engine to climb into the fat part of the power band (search Bowden Cable).

Great cars. Now the car will do 0-60 in around 9sec, and has broken 125mph on an open stretch, still climbing.

Also, don't neglect the fluids, these engines don't wear out, but can be killed. Last, clogged fuel and air filters will choke the engine and can also be part of your problem.

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Gone to the dark side

- Jeff

Baby Mog has pretty much nailed what to look at.

Mine was running 25 second 0-60s when I bought it. Filling the fuel filter with 1/2 can of SeaFoam injector cleaner and dumping the rest of the can into the tank was my first step. I ran it a few minutes like that and then gave it an Italian tune up. After 3-4 runs doing the 0-60 the car belched out a huge cloud of black smoke and really picked up. After a couple more runs I was down to 15 seconds or so.

Since then I have removed the ALDA and gained a few more seconds.

I bought the EGR kit, but have not installed it yet.

I need to pull the injectors, clean them, and have them serviced next.

The huge improvements came from using injector cleaning fluid and doing an Italian tune up. The ALDA removal helped with response from a dead stop also.

-Jim

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1995 S350D, Green with black leather interior.
Bought January 2008 w/ 233,xxx miles.
I did 22,000 miles during the first year of ownership.

Thanks to all of your responses. I am going to try a few things you have all mentioned. Thanks again!!!

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1985 Mercedes Benz 300TDT, 170,000 miles
1983 Mercedes 300SD, 200,000 miles (sold)
1988 Toyota 4x4 Xtra Cab
2003 Toyota Tacoma
2003 Toyota Landcruiser
1987 Mercedes 300D
1991 BMW 318is

I'm surprised noone has mentioned the Air Recirculation Valve (ARV). The ARV modulates turbo boost under the control of the engine ECU. The ARV is distinct from the wastegate, which is completely mechanical.

We don't fully understand how/why the ARV was used. It seems to have something to do with emissions control, in conjunction with the dreaded trap oxidiser. If the trapox has been replaced (it has, right?) the ARV is not necessary (foreign market cars without a trapox also did not have an ARV.)

The ARV can be disconnected. It is controlled via one of the two vacuum valves beneath the air cleaner. Simply disconnect and plug the vacuum line to the ARV. See if the car drives better.

On an '87 I used to own the ECU would more or less randomly command the ARV to dump all boost. Just cruising along the car would lose lots of power, requiring more thottle to maintain speed. Very annoying. Disconnecting the ARV eliminated the problem, and it ran like a scalded cat from then on.

- JimY