Hello,
I was curious if the boost is adjustable on a 1987 300sdl. I have read many posts about adjusting the ALDA and then the boost on the earlier 5-cyl diesls with good results and wonder if the 6-cyl would respond similarly. I looked at the instructions for the 5-cyl adjustment and the 6-cyl is a bit different. For one there does not appear to be an adjustment screw for the wastegate under the spring, it appears to just have a spring(mine had a yellow strip on it, maybe there are differnt tensions for differnt pressures). Im assuming that the values stated for the 5-cyl regarding max spec boost(0.9-1 bar under full load at 4000rpm, with overboost curcuit kicking in at 1.1 bar) apply to the 6-cyl as well. Also I take it that the ALDA unit is adjustable like in the 5-cyl as well. I will test boost as soon as I get my hands on a gauge. The car isnt too fast on the highway, almost 240d accelaration with pedal floored, but around town its not too bad, seems to have good pull from ~2500 to ~3100 then not much power, and this only in the first 2 gears. Timing chain was changed 20k ago and pump timing was checked, and all filters and fluids were changed, with car having ~230k now. No smoke upon "flooring" leads me to believe the car is running a bit lean and/or turbo is going. Im assuming its the lean situation since the turbo spools up fine and pulls well for a little bit. The trap oxidizer was replaced with the straight pipe fix at ~150 along with the turbo. Any comments or suggestions are welcome.

I have my '87 300SDL (118,000 miles) in the shop and they are addressing a similiar performance problem. I don't have all the details but there is a vacuum that was clogged with oil causing sub-par acceleration highly noticable in the 40+ mph range. I am having this replaced and will report back with more specifics and feedback on improvements.

Boost on the '86-'87 300SDL is not adjustable. The amount of boost is determined via an engine load sensor which, when activated, decreases the amount of fuel delivered to the engine, thereby reducing power.

The boost will not increase the performance of this engine, all you have to do is turn a little more fuel to it by shimming the anaroid valve. If you have to ask how, you should take it to a tech that knows how. Oh yeah be sure that the anaroid valve is getting the boost from the turbo/intake.

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Benzmac:
1981 280GE SWB
1987 16V
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