Any severe damage from over adjusting rack dampener - PeachParts Mercedes-Benz Forum

retx · #1 03-03-2007, 04:10 PM

Almost every post about adjusting the rack bolt says to back it out until it idles rough/shakes, and then screw it in JUST until it stops. Today, while adjusting mine, I noticed that it would stop shaking but with further adjustment, the engine would continue to run smoother.
My questions would be, is there severe damage from "over adjusting", and could the continual smoothness mean that the rack dampener pin/spring is old and fatigued? Most posts say that it should take only a fraction of a turn. I would say mine became EXTREMELY smooth at just over a full turn.

240Joe · #2 03-03-2007, 04:12 PM

I do know that if you screw it in too much, the engine will die when cold. I screwed mine in until that became a problem, then backed it out until it stopped dying on me.

It seems pretty smooth at this point.

I assume you have the new rack damper.

240Joe

retx · #3 03-03-2007, 04:19 PM

i dont really know if it has been changed before. I cant assume i have the new one.
visually, can you tell?

240Joe · #4 03-03-2007, 04:24 PM

I think the new versus the old can be determined by the color of the pin. One is silver and the other gold, but I don't remember which.

Do a search on this board, and I'm sure you'll find out.

240Joe

retx · #5 03-03-2007, 06:17 PM

yeah, i have searched. i searched for nearly an hour. unless gold or silver has a dirty, old, used color even when cleaned...then i have no clue what color it is.

sailor15015 · #6 03-03-2007, 06:46 PM

Gold=updated. I think that you'll be fine as long as you don't grind down the head of the bolt to allow it to screw in farther. I remember one thread specifically where someone did this and it did indeed damage something internally in his ip and he had to get another from a junkyard. Don't modify the new bolt and you should be good to screw it all the way in. I had to screw the new pin all the way in on all three 617's but they ran good with it there, no rough cold starting.

retx · #7 03-03-2007, 07:01 PM

well im not sure which pin/bolt i have. its running smoothly right now. thanx sailor, for the info. thats kinda what i was wondering.

SlashJoe · #8 03-03-2007, 08:22 PM

Not trying to steel the thread, but is this the rack dampener bolt? Is this the old one? It looks old and I cleaned the big nut a little and it looks brass. And does it look like it’s screwed in all the way?

I have a cold start issue. When I start it, I have to hold the pedal in to have the RPM around 750. Otherwise it idles very rough at 500 and the air cleaner housing vibrates so much it hits the valve cover. The air cleaner bracket and rubber buffer mounts are good. When it warms up, it idles at about 550 and doesn’t vibrate that bad.

Should I back out the bolt a little, or do I need a new one?
Don’t want to sound stupid, but do I loosen the big nut first, then hold it and unscrew the bolt? Do I do this when the engine is cold or warm?
Thanks,
Joe…

biobenz617 · #9 03-03-2007, 08:54 PM

Thats the bolt. I think the large hex part is a lock nut and the smaller is actually the bolt, but it's been a while since I touched it.

Having the bolt in too far will make it so the idle governor can't move the rack, which means it can't get the pump up to normal idle. The bolt is actually applying pressure to a part inside the governor and this friction keeps the governor from erratically moving the rack back and forth when it gets to the idle "range". The more friction, the farther off it will be from the idle setpoint.

Strangely enough when i was adjusting mine, I removed it completely and decided to stop the engine for some reason using the lever. The governor almost completely compensated for my efforts, and the engine continued to put along probably around 500rpm.

toomany MBZ · #10 03-04-2007, 06:28 PM

When installing new bolt hand turn cw untill resistance. Be sure to save flat o ring, and use old lock nut too. Back out till smooth. Tighten lock nut. The large nut [14mm] is the lock, loosen, adjust small [12mm] bolt. Gear wrenches are wonderful. The one I replaced, looks more gold {brass?} than silver. Hope this helps.

SlashJoe · #11 03-04-2007, 06:36 PM

Cool, thanks. I'll try this with the old one first. Need to finish the axles first.

Do you adjust when cold or warmed up? And is the 750 the right RPM?

toomany MBZ · #12 03-04-2007, 06:57 PM

Quote:

Originally Posted by SlashJoe

Cool, thanks. I'll try this with the old one first. Need to finish the axles first.

Do you adjust when cold or warmed up? And is the 750 the right RPM?

I've heard, and used warm engine. Don't know if it matters. RPM good.

SlashJoe · #13 03-10-2007, 11:45 PM

Turning that bolt didn’t make any difference what so ever. I took the bolt out and it’s silver. The tip seems spring loaded. Anything I can do here, ther than getting a new one?
I might just need to adjust idle speed. I don’t have a deep socket to get to the lock nut on the idle speed screw.

MBeige · #14 03-11-2007, 12:43 AM

Quote:

Originally Posted by toomany MBZ

When installing new bolt hand turn cw untill resistance. Be sure to save flat o ring, and use old lock nut too. Back out till smooth. Tighten lock nut. The large nut [14mm] is the lock, loosen, adjust small [12mm] bolt. Gear wrenches are wonderful. The one I replaced, looks more gold {brass?} than silver. Hope this helps.

What flat O-ring?

I didn't see any on mine when I adjusted it and/or replaced with a new one!