Clutch adjustment needed?

[S11A]

I have a couple of odd things I am trying to troubleshoot which may be related and would appreciate any advice:

1. When I put on the parking brake at idle the revs drop. When I release it the revs pick back up. It is low enough that I set the hand throttle over a notch or two if it is going to idle for a bit.

2. When I back down the driveway (downhill) in reverse the revs drop and the engine almost dies with the clutch in.

3. I get a bit of a crunch from 2nd and I am fairly certain I am double (de)clutching properly.

It's a diesel if that matters.

Any suggestions would be appreciated.

[gwmaxhunter]

Hi. first i'd adjust the clutch to specs and then see what happens. not likely the flywheel would warp in this. pressure plate could. disk could warp or something could embed in the fiber, a chunk of fiber, metal, rock. any contaminant like that. the pilot bearing could gaull... that is pick up metal from one spot and put it in another....grease could be contaminated with dirt and age turn it to a hard tar like substance and give high resistance......also you could not be getting the full travel of your throw out bearing, bearing worn, linkage worn, master or slave restricted in motion, possible air in system....i should say master or slave not giving full motion...does pedal have full motion......if i have missed anything luk clutches should have a website with diagnostic problem solvers there.

[SafeAirOne]

Not so sure all those items are related.

Item #1: Believe it or not, the first thing that comes to mind when you talk about the idle changing with application of the hand brake is engine and transmission mounts. If yours are soft, the position of the powerpack can shift just enough to alter the distance between the carburetor and the bulkhead (to which the other end of the throttle connecting rod is firmly affixed).

The bulkhead and the throttle rod stay in the same place but the carb, attached to the shifting engine, moves in one direction or the other, actuating the throttle plate in the carb slightly, changing the engine RPM.

My 109 has the factory optional brace between the bellhousing and the transmission crossmember to keep the whole works from shifting around, but the rubber bushings are...um...deteriorated, let's say...and I can feel everything shift slightly when I apply the handbrake.

Just a WAG on my part, but I can't think of any other way that engine RPMs could change as you describe.

#2: Calibrate the float in your carb bowl. Again, just a WAG--I don't use a carburetor, but other than an empty fuel tank, I can't think of anything else that fits the symptoms. Oh, except that if you have a 109 Station wagon (rear fuel tank) and yoru electric boost pump doesn't work (the electric pump on 109 station wagon is there because the engine-driven mechanical pump can't draw enough head when the rear-mount tank is low (as when climbing or backing down a steep hill).

#3 Check to make sure your clutch master cylinder is getting enough throw. If it is, check to make sure your clutch slave is adjusted properly. If it is, check for worn bushings and parts in that God awful clutch release cross shaft mechanism contraption that you pre-SIII folks use to un-clutch. If that's all OK, add a little more length to the slave cylinder rod, but not so much that the clutch slips with the pedal all the way up.

[EDIT:] Just re-read your post. If it's only happening in 2nd, and not in first, AND you have a fully synchro-mesh transmission, you may have a synchro issue. Not sure if some of the late IIAs had a fully synchro transmission or not, but I figured I'd throw that out there just in case. [/EDIT]

Take all that for what it's worth, but that's the way I'd initially attack all that stuff.