Some questions about my new SD - PeachParts Mercedes-Benz Forum

muleears · #1 10-22-2010, 11:26 AM

This is an '83 W126 with 152K. I have some concerns and some proposed repairs please tell me if there are more or if I am on the wrong track. Both fuel filters have just been changed.

1. Starts easily and idles smooth, but, has NO POWER when cold and improves somewhat when warmed up, but still way under normal power. I plan to a) adjust the valves, don't know when last done, b) clean banjo bolt and boost controller, c) adjust ALDA, d) clean injectors, e) check pump timing

2. Upshifts very quickly (could be related to #1 above) It's in 4th by 33 mph, regardless of pedal position, it shifts before much boost is evident. Shifts are of correct firmness. Doesn't downshift until almost stopped. It will shift normally if shifted manually. Will downshift when kickdown is depressed. Improves as it warms but still shifts much too early. Has a 1-2 flare when cold. I plan to a) fluid and filter, b) adjust bowden cable (have adjusted two turns (half turn at a time) with improvement). c) check vacuum controls of transmission (will need further help with this)

What am I missing or is this a good plan of attack?

Thanks for your help.

Aquaticedge · #2 10-22-2010, 11:30 AM

check your turbo for play etc. also check the boost fittings (if it has it) they tend to clog up with soot etc.

and your spot on with the transmission. make sure all the adjustments are perfect. Another thing to look at on the engine is the Valve clearance if they are out I understand they can cause all sorts of problems

TX76513 · #3 10-22-2010, 11:37 AM

Sounds like you have a good plan of attach. When looking at vacuum lines pay particular attention to elbows and connector T's that are made out of the softer rubber. Then tend to crack and close inspection is required. You may find that buying a couple yards of line and re-doing all the under hood vac's is a good (and easy) way to assure vacuum is running to spec. The transmission is very picky about vacuum.

Brian Carlton · #4 10-22-2010, 08:25 PM

Quote:

Originally Posted by muleears

This is an '83 W126 with 152K. I have some concerns and some proposed repairs please tell me if there are more or if I am on the wrong track. Both fuel filters have just been changed.

1. Starts easily and idles smooth, but, has NO POWER when cold and improves somewhat when warmed up, but still way under normal power. I plan to a) adjust the valves, don't know when last done, b) clean banjo bolt and boost controller, c) adjust ALDA, d) clean injectors, e) check pump timing

Agree with all of the above. Be aware that the ALDA may not provide the desired adjustment due to the inability to move the screw sufficiently (don't snap it). You could always remove the ALDA for testing purposes to see if the power returns. It's two wrenches and two minutes on the SD.

Quote:

Originally Posted by muleears

2. Upshifts very quickly (could be related to #1 above) It's in 4th by 33 mph, regardless of pedal position, it shifts before much boost is evident. Shifts are of correct firmness. Doesn't downshift until almost stopped. It will shift normally if shifted manually. Will downshift when kickdown is depressed. Improves as it warms but still shifts much too early. Has a 1-2 flare when cold. I plan to a) fluid and filter, b) adjust bowden cable (have adjusted two turns (half turn at a time) with improvement). c) check vacuum controls of transmission (will need further help with this)

This is most certainly a failure of the Bowden cable. Either it's wildly out of adjustment or simply disconnected under the hood. The cable must be properly attached to the throttle linkage and it must extend as the throttle linkage opens the rack.

If you properly make the adjustment to get the power back in the first paragraph, the problem of the 1-2 flare will disappear.

ImBroke · #5 10-22-2010, 08:36 PM

Cal, sounds like a good plan so far. I need to see this new beast.

bluebird · #6 10-22-2010, 08:50 PM

When I had throttle linkage problems, I went to a friend who was the original owner and mechanic on his own car parked next to his car and pulled each throttle linkage shaft off both cars and compared his length to my throttle shaft length and adjusted mine to match. Worked great, and while I was at it I lubed both his and mine with ATF.

muleears · #7 10-22-2010, 08:55 PM

So far I have cleaned the banjo bolt, turned the ALDA out one turn and backed out the bowden a total of 2 more turns (total of 4.5 from where it was when I got it). Now I have a little more power from a stop (ALDA) and it shifts at higher speeds, actually getting close to where it should. Still have an occasional 2-3 flare and 3-4 is a very soft, slow shift. It will downshift now from 4th to 3rd when slowed to about 18 mph. Still doesn't downshift with pedal pressure though. For example: when cruising at 35 mph in 4th, no amount of pedal pressure will prompt a downshift until the kickdown is engaged. I have not done the valves, I hope to Sunday morning but will be babysitting the grandkids. Two little helpers may make it too difficult! I have not checked pump timing, I may have to leave that to someone who knows how

.

Where should I go from here?

Tony: you have a PM

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