I've had this problem of poor acceleration for some time but it seems to be getting worse. The car has 185,000 miles and is in otherwise very good condition. I've had the valves adjusted and the fuel pump adjusted. I have also replaced all the filters. Nothing has helped. My mechanic said he needs to check the compression. I've heard that sometimes the fuel pump goes on these cars. The car really can't get moving until the turbo kicks in in. It runs ok on the highway. I have been using Red Line Diesel Fuel Additive. Are there any things that I should be looking at?

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Ed
1985 300D w/ 196,000 miles

I would check the base setting of the anaroid valve and the turbo tube.

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Benzmac:
Donnie Drummonds
ASE CERTIFIED MASTER AUTO TECHNICIAN
MERCEDES SPECIALIST 11 YRS

Check all the boost control hoses -- they go from the intake manifold to the ALDA and to the transmission switchover valve and vacuum amplifier (and usually some other valves, too) and the boost controller on the turbo. All the rubber ends are probably shot, causing the turbo signal to be lost until the pressure really goes up. Causes the IP to inject fuel as it it were a naturally aspirated engine, then jumps it up about 2000 rpm suddenly.

My 87 is doing this rather badly -- I replaced all the vacuum side the other day, and it now shifts better, but still "lunges" after no throttle response unless I really get on it. I suspect all the hoses -- they have nice little clamps on them, so I've been waiting for some time to get to them.

You might also want to check the condition of the turbo itself, too -- take the intake hose off and see if the wheel turns smoothly and easily. If it is sticky or rough in rotation, you need new bearings. Bad turbo makes these things SLOW until the turbo pops on -- they don't inject as much fuel as the na engines without boost.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Ok Peter, I think I did everything you said.
1) Checked the boost control hoses coming form the intake manifold to the switch over valve and the from the switch over valve to the ALDA. They were ok. No cracks or breaks visible. The rubber connectors looked ok too.
2) I checked the hollow bolt at the back of the manifold. It was clean. I checked the hollow bolt at the ALDA. It was packed with grime. I cleaned that out.
3) I checked the turbo. The wheel turns smoothly and freely.
4) I road tested it. The car still accelerated poorly.
5) I by passed the switch over valve to see if that might be the problem. Still no improvement.

I thought I had my problem solved when I discovered the crud build up in the hollow screw at the ALDA. There certainly was nothing happening with that bolt clogged the way it was.

What do you suggest I look for now.
Thank you for the help!
Ed

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Ed
1985 300D w/ 196,000 miles

Do you make black smoke upon acceleration or not?

Lots of smoke = fuel not burning (low compression, bad injectors, etc)

No smoke or very little = no fuel delivery. Lots of causes, including a bad suction line from the tank allowing air into the fuel system.

your ALDA may also be full of crud, in whick case it will sticka and restrict fuel delivery until the boost is way up -- replacement is the cure.

Worst case is that the governor is shot, will require an IP rebuild.

Have the compression checked, that is MUCH cheaper than taking the IP off and getting it checked. I'd replace the ALDA on the assumption that if crud collected in the hollow bolt it collected on the diaphram, too, and has screwed it up. Also cheaper (and easiery) than checking the IP.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

drawde,
Welcome to the diesel club! They all take off SLOW.

TurboTurbine,

The Calif 84 300D/SD models take off SLOWER than other diesel models of the same size due to the turbo's recirculation valve which is controlled by a vacuum hose.

David

David, is there any way i can improve the accel of my car at least a little? what do you suggest?does the muffler play any part in the power of the car as mine is pretty well shot! i have yet to buy one and replace it but i want to get a little more knowledge first.
thanks
Karl

Peter-
I contacted the parts shop and spoke to Phil. He said that the ALDA can not be bought separately. That it is part of the injection pump. What say you?
Thanks
ed

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Ed
1985 300D w/ 196,000 miles

ON TOP OF THE ANEROID THERE IS A FACTORY SEALED ADJUSTMENT SCREW.
REMOVE THE PLASTIC/ALUMINUM SEAL AND LOOSEN THE 10MM NUT,TURN THE SCREW COUNTERCLOCKWISE OUT AT 1/4 TURN INCREMENTS AT A TIME (NOT TO EXCEED ONE FULL TURN) UNTIL POWER IS RESTORED.
THIS ALLOWS GREATER FUEL DELIVERY AT LOW R.P.M., BUT ALSO ALLOWS MORE SOOT OUT OF THE TAILPIPE.
SIMPLE ADJUSTMENT GREAT RESULTS!
MF