Rack Damper Bolt ID (Pic) - PeachParts Mercedes-Benz Forum

TomJ · #1 10-15-2003, 10:15 PM

Anyone have a pic of the "new" damper bolt (Governor Idle Adjustment Pin)?

Here's a pic of the one removed from my 300D. Not sure if it's the "new" style or the "old" style.

Spring feels firm, but the plunger is square (not convex as others have suggested the new style is.)

You make the call, old style or new:

lrg · #2 10-15-2003, 10:44 PM

That's an old one. The new pins are bright cad plated.

TomJ · #3 10-15-2003, 10:46 PM

Quote:

Originally posted by lrg
That's an old one. The new pins are bright cad plated.

OK, I suspected that. But then again, this "might" have been bright cadmium plated at one time too. Would be nice if there was another way to ID by part feature?

Diesel911 · #4 06-14-2010, 08:59 PM

Quote:

Originally Posted by TomJ

OK, I suspected that. But then again, this "might" have been bright cadmium plated at one time too. Would be nice if there was another way to ID by part feature?

While it is possible for the Gold Colored plating to come of the Bolt exposed to the Exterior of the Fuel Injection Pump/Governor the plating should be visable on the parts of the Bolt that is screwed into the back of the Governor.
Unless some one used a Wire Wheel and buffed off all the plating.

engatwork · #5 10-16-2003, 07:10 AM

Not sure if it is old/wore out or the old style but the "tip" at the left end of the photo is supposed to be kinda rounded.

TomJ · #6 10-16-2003, 01:55 PM

Well, NO ONE at ANY web-based parts house had one of these in stock, so I ended up at our local dealer and bought one of the two they have on the shelf.

Cost me $30. They see me a lot, so they give me a deal on parts.

Here's the two sie by side for future ref/comparision for others, new on top, old on bottom:

Here's a closeup of the tips. The tip on the new one is not a perfect radius, more of a bevel with a flat .015 tip (as opposed to the perfectly flat tip of the old one) - new on right, old on left:

The new one does have a stronger spring, but marginally so. We'll see what difference it makes.

Dcraig · #7 10-16-2003, 08:52 PM

Tell us how that new pin works for you. I bought one for my old CD and I didn't think it made my idle any better. I was just thinking about buying one for my 'new' CD.

Craig

TomJ · #8 10-17-2003, 12:33 AM

Quote:

Originally posted by Dcraig
Tell us how that new pin works for you. I bought one for my old CD and I didn't think it made my idle any better. I was just thinking about buying one for my 'new' CD.

Craig

Not one bit of diff. But...., not that I could tell. As soon as I started it up (after much electrical work, tranny swap to a 4-spd from auto, various engine mods, etc.) there was a STRONG nailing sound coming from the front of the engine.

Turns out, it was a sensor that was getting chewed up by the balancer. Looks like the tach sensor. Would make sense since I now don't have a working tach. Wonder what that cable/sensor will cost.

Dcraig · #9 10-17-2003, 01:01 AM

Awwww bummer.

Beagle · #10 10-17-2003, 01:22 AM

Tom

There is no such thing as a "rack damper bolt".

That pin, as you quite correctly call it, is the "Governor Idle Adjustment Pin" and that is exactly what it does - adjusts idle RPM - Period! It acts as a stop against the throttle linkage bellcrank arm inside the governor housing. The ONLY time the spring-loaded plunger comes into play is when you stop the engine via the manual stop lever on the linkage, allowing the rack to move past the idle setting to zero delivery. It has no function whatever in smoothing out a rough idle.

The pin was modified many years ago as it had a habit of jamming in the brass bush and the square tip burring the lever arm making proper idle adjustment impossible. The fix was to bevel the tip and fit a stronger spring.

On later MW pumps that pin was deleted from the Governor back plate and the spring plunger incorporated in the idle adjust screw mounted vertically on the Gov. housing behind the pump.

ROLLGUY · #11 06-14-2010, 06:51 PM

Quote:

Originally Posted by Beagle

Tom

There is no such thing as a "rack damper bolt".

That pin, as you quite correctly call it, is the "Governor Idle Adjustment Pin" and that is exactly what it does - adjusts idle RPM - Period! It acts as a stop against the throttle linkage bellcrank arm inside the governor housing. The ONLY time the spring-loaded plunger comes into play is when you stop the engine via the manual stop lever on the linkage, allowing the rack to move past the idle setting to zero delivery. It has no function whatever in smoothing out a rough idle.

The pin was modified many years ago as it had a habit of jamming in the brass bush and the square tip burring the lever arm making proper idle adjustment impossible. The fix was to bevel the tip and fit a stronger spring.

On later MW pumps that pin was deleted from the Governor back plate and the spring plunger incorporated in the idle adjust screw mounted vertically on the Gov. housing behind the pump.

I know this is an old thread, but it helped me find the part I was looking for. I too have only heard it called a "Rack damper Bolt" (Diesel Giant calls it this as well). I tried to find it by that name and nobody at any parts house knew what I was talking about. When I searched "Rack damper Bolt" on this site, I found this thread. After calling my local Import parts store with the description "Governor Idle Adjustment Pin", no problem. They were available (a little pricey at $68.00), but available the next day. Yes it is very important to use the name that the manufacturer calls it, otherwise you will not get the part you think you need because of an improper name.

Dcraig · #12 06-14-2010, 08:27 PM

My parts shop online calls it a "injection pump idle adjuster screw"

jkubica · #13 06-15-2010, 11:57 AM

Quote:

Originally Posted by Dcraig

My parts shop online calls it a "injection pump idle adjuster screw"

Hi
FWIW - ******** AZ calls it "adjustment bolt at rear of injector pump"
Joseph

TomJ · #14 10-17-2003, 10:54 AM

Quote:

Originally posted by Beagle
Tom

There is no such thing as a "rack damper bolt".

That pin, as you quite correctly call it, is the "Governor Idle Adjustment Pin" and that is exactly what it does - adjusts idle RPM - Period! It acts as a stop against the throttle linkage bellcrank arm inside the governor housing. The ONLY time the spring-loaded plunger comes into play is when you stop the engine via the manual stop lever on the linkage, allowing the rack to move past the idle setting to zero delivery. It has no function whatever in smoothing out a rough idle.

The pin was modified many years ago as it had a habit of jamming in the brass bush and the square tip burring the lever arm making proper idle adjustment impossible. The fix was to bevel the tip and fit a stronger spring.

On later MW pumps that pin was deleted from the Governor back plate and the spring plunger incorporated in the idle adjust screw mounted vertically on the Gov. housing behind the pump.

Well..., really sorry, but when something is COMMONLY called a "rack damper bolt" because it..., let's see, by your own definition DAMPENS THE RACK!! Then I'll continue to call it a rack damper, even if it's German designation (we all know how accurate their parts designations are!) is a Governor Idle Adjust Pin.

Furthermore, by your own def, it does NOTHING to effect idle so again, we see how accurate THEIR naming is ("Idle Adjust Pin").

Also, since it does absolutely nothing for idle (as you claim), I will run right out this very day and get my ears checked as every time I turned it in I notice (imagined of course) that the idle get's rougher and it lopes, smooths out when it's out far enough that it just touches the rack (sorry, there's that abominable word again).

So, it's just my imagination that it smooths the idle and that it dampens the rack (hence "rack damper"). Thanks for clarifying.

Diesel911 · #15 06-14-2010, 09:09 PM

Quote:

Originally Posted by TomJ

Well..., really sorry, but when something is COMMONLY called a "rack damper bolt" because it..., let's see, by your own definition DAMPENS THE RACK!! Then I'll continue to call it a rack damper, even if it's German designation (we all know how accurate their parts designations are!) is a Governor Idle Adjust Pin.

Furthermore, by your own def, it does NOTHING to effect idle so again, we see how accurate THEIR naming is ("Idle Adjust Pin").

Also, since it does absolutely nothing for idle (as you claim), I will run right out this very day and get my ears checked as every time I turned it in I notice (imagined of course) that the idle get's rougher and it lopes, smooths out when it's out far enough that it just touches the rack (sorry, there's that abominable word again).

So, it's just my imagination that it smooths the idle and that it dampens the rack (hence "rack damper"). Thanks for clarifying.

Yes that bolt has at least 2 different names on internet part places and on the Fourms the name gets bent a little.
I dislike the term "Hard Lines" that is used on this Forum to indicate the Steel Fuel Injection Tubing but that is what you guys use and so that is what I use.

I also agree that the Idle Adjustment Screw is on the Throttle Lever side of the Governor and that the Bolt/Pin is a different part.