'83 300SD no power starting out - PeachParts Mercedes-Benz Forum

#1 12-05-2003, 10:17 AM

I have a 1983 SD with 197k miles on it. It starts fine, although the idle is somewhat rough, but has no power to drive off until it warms up & then I have to downshift to get the car up to speed.

Once I'm at a higher speed the vehicle seems to be ok - I can do
85 mph all day.......

MrCjames · #2 12-05-2003, 10:56 AM

There is a vacuum line from the intake manifold that attaches to one side of an electric valve. Follow the line to the electric valve and you will notice a second line on the valve which goes to the aneroid compensator on the injection pump. This valve will be located relatively close to the left front shock anchor attached to the insulated fire wall panel. Connect the two lines together to by-pass the valve then test drive the vehicle. If it has good, low end response then you need to replace the switch over-valve.

Keep us posted if you need more assistance.

Ken300D · #3 12-05-2003, 12:06 PM

I'm working on the same issue with my 1984 300SD. At least it seems to me to be low in take-off power compared to the 1982 300D with the same engine.

The thing about the lines that MrCjames mentioned is that I thought they had to do with turbo boost fuel enrichment. What I have seems to be a low power issue from idle up TO the turbo kicks in - then it goes.

So, I'm going to be checking the valve adjustment and timing chain stretch. Hopefully I can do that this weekend - the car is in storage away from my house.

Will let you know what I find out.

Ken300D

jerryyoung · #4 12-05-2003, 03:24 PM

Don't forget to check/clean the banjo fitting at the intake manifold as this feeds the line to the valve.
Jerry

86560SEL · #5 12-05-2003, 11:15 PM

The local 1984 300SD with 336K that I was considering was doing the exact same thing. Idle was rough at times and very slow to start out. Going back up the grade- I was going at a steady 5 mph for about 20 seconds, then it finally gained speed.
It also made the transmission have a harsh 1-2 and a quick 2-3 shift, so I passed on the car. It also had squeaky brakes and a rattling from the right rear. Probably was not a bad problem at all and was probably a great deal. Seller said he would sell for $2100, but I think I could have bought it for $1700. Car was white, with an excellent body and interior. Garage kept since new. I passed on it because of the engine and transmission behavior.

nhodges · #6 12-05-2003, 11:16 PM

You don't know low power until the banjo bolt and or the line to the switchover valve gets plugged with gunk.

#7 12-06-2003, 08:09 PM

I checked and the valve has been bypassed. I plugged the vacuum line to the EGR & then turned the ALDA screw CCW
1 turn (virgin screw).

I had no smoking at all on idle....drove off & the car actually went fast! Stopped at market & decided to then drive at highway speed. Car then started having problems with power at high end.

Came home....cleaned banjo bolt (which was loose), blew air through tube....

Now I'm back to where I started with no low end power.....haven't tried yet at highway speeds....

reddog · #8 12-06-2003, 09:33 PM

Turn the adjusting screw on the ALDA ccw all the way out, then turn back in one half to one turn. Go to Richard Easley and Stu Ritter's web site and learn how to adjust your turbo wastegate, then hold onto your hat when you road test

Ken300D · #9 12-15-2003, 10:38 AM

So far I have found that the timing chain does not have significant stretch.

The valves all appear to be way too tight except for one.

The banjo bolt at the rear of the intake manifold was loose and was also missing the little washers (copper I think) that help it seal. You could tell the banjo bolt was leaking too because the oil mist generally found in the intake had gotten out and collected some dirt and dust.

Have not put things back together yet to test drive. Will let you know of further developments.

Ken300D

#10 12-15-2003, 08:51 PM

I changed the inline fuel filter which looked like it had algae, then added a bottle of CRC Diesel fuel system treatment. Drove down the freeway & car started losing speed until it was a hazard to drive - couldn't go over 40....turned very sharply off road & ever since I made the sharp turn car has been running like new - total power & fast acceleration. Still have a rough idle.

I'm wondering if additive & sharp turn dislodged gunk from fuel tank strainer? I'm at a loss as to why the sudden fix?