I am going to be changing my valve stem seals on my 1981 300SD. I looked through the forum and found the procedure listed below. I have a question on step 1, didn't get to far did I..?? Do I have to remove my cam shaft to do this job?? At the bottom of step 1 it states "Loosen stuck camshaft bearings by means of light blows with a plastic hammer " but it doesn't say anything about removing the cam. It does state to remove the rockers by groups cylinders 1,2 in one group and cylinders 3,4,5 in the other group. I would think you need to relieve the pressure between the valve and the cam shaft before you can get the rockers out...??? I don't think you can set the cam so all the rockers are free in the group.

Any Ideas????????

Phil Corby


Procedure:

valve stem seal replacement for 617.95
This is regarding older diesel engines.


1. remove rocker arms with rocker arm brackets.

*Always install rocker arm at the same spot from where it has been removed.

REMOVAL
*Set camshaft in such a manner that the rocker arm is free of load. That is, the cam tips should point away from rocker arms.
*Screw out fastening screws of rocker arm bearing brackets.
*Completely remove rocker arm group in upward direction.
*Loosen stuck camshaft bearings by means of light blows with a plastic hammer.


2.Remove valve springs. .

REMOVAL
*Set piston of respective cylinder to ignition TDC.
*place holding wrench on valve spring retainer.
*unscrew cap nut
*unscrew counternut
*remove valve spring retainer and valve spring. Keep the parts organized. Do one cylinder at a time.

3.Force off valve stem seals with a screwdriver or pull of with pliers. Do not damage valve stem or valve guide.

4.lubricate new valve stem seals and mount by means of assembly mandrel. (I used two blunt tools to push them on). The mandrel is part no. 617 589 00 43 00 I don't think it is needed.

5. Install valve springs.

INSTALLATION
*Insert valve spring with narrow coils toward cylinder head (color dots at top)
*the rest is just the reversal of removal.

Repeat the above directions for each cylinder until all the seals are changed. I made sure the springs and retainers went back on the same valve. I don't know if it matters.


6. Install rocker arms with rocker arm bearing brackets.

INSTALLATION
*Set complete rocker arm group and screw down(38 Nm)
*(the rocker arm bearing brackets are located by means of fitted sleeves.)

7. Adjust valve clearance

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1981 300SD 164K Miles