Call: 888-333-4642  

Valve Stem Seal Replacement

on the 1992 300E

M103 Engine / W124 Chassis

by Ron in SC


Valve Stem Seal Replacement M103 engine

General Information
Get the stem seal kit, new valve cover gasket, the two breather hoses that go from the valve cover to air cleaner housing and intake manifold (if you have never changed them they will be very brittle and probably break), two cans of brake cleaner to clean inside of valve cover and the oil pipe that sprays oil on the camshaft. Also get a meter of that clear plastic vacuum hose, you'll most likely see some under the air
cleaner housing that you'll want to replace.


I offer no opinion relative to the difficulty of this job. That will depend on experience. Some may think it's easy while others may think it's difficult.

The procedure I've outlined is what worked for me. Standard safety procedures and precautions, including the use of safety goggles and proper tools and equipment, should be followed at all times to eliminate the possibility of personal injury or improper service which could damage your car or compromise its safety.

Should you find an error in these instructions please let me know so I can correct it.

Tools are available for Rental Here. all these tools are made in the USA

Tools you will need: (based on how I did the job)
Parts you need:
Remove Air Cleaner
detach breather hose from top valve cover to intake manifold and detach the breather hose from the top of the valve cover to the air filter housing
remove three 10mm hex head screws that hold filter housing and disconnect electrical connector on intake and lift entire housing off with hose connected to the air filter housing

Fan Shroud
remove fan shroud, the part that you turn and pull out

Remove lower engine cover

Remove Valve Cover
remove valve and cover plate inside of valve cover that is held in place by phillips head screws and clean out with brake cleaner
remove bolt that holds transmission filler tube to head and push to side a little
plug six oil drain holes in head with plugs, stick each down hole about 2"
remove oil pipe and spray out with brake cleaner
pressure wash valve cover to blast off as much peeling paint as possible. I got most all of it off. Obviously this step is not necessary.

Changing Seals
I did one cylinder at a time as follows:
1-remove spark plug, however, prior to removal you may want to use compressed air to blow clean the area where the spark plug is fitted to remove any grit that might fall into the cylinder when you remove the plug
2-screw in pipe with whistle on the end
3-turn crankshaft clockwise very slowly by means of the ratchet and 27mm socket, keep turning until whistle starts to blow
4-keep turning slowly, the whistle will blow a few more times depending on how much you turn the crankshaft, when the whistle stops you are at TDC, to be positive you can remove the tool with the whistle on it and insert a tiny streamlight or similar LED flashlight into spark plug hole and you will see the top of the piston
5-make sure the socket is on the crankshaft bolt and that the handle of the ratchet rests against the A/C compressor that way the engine can not turn when you supply air
6-if you removed the tool with the whistle on it you need to reinstall that tool in the spark plug hole. Then remove the whistle from the top of the tool and attach air supply and pressurize cylinder to 75 psi, which is about 5 bar which is pressure specified in the Service Manual for Engine 103
7-unbolt rocker arm
8-as you lift off rocker arm use pencil magnet to remove ball socket on each side, note orientation of ball socket for proper reinstall later
9-compress spring and remove valve collet halves with pencil magnet
10-remove valve spring
11-remove old seal with pliers
12-install new seal, use the correct one for intake or exhaust and use the assembly sleeve for installing the intake seals only, you place it over the valve stem, put a little oil on it and slip the valve stem seal over the assembly sleeve and then press the seal in place with your fingers, then pull the assembly sleeve straight up to remove it, put oil on exhaust stem seals also to aid installation, the assembly sleeves are not used to install exhaust seals
13-reinstall spring & collets
14-do same for other side Air pressure should not be removed until both the valve springs are reinstalled, i.e., the collet halves are properly installed.
15-reinstall ball sockets, & rocker.
16-Go through same process for the rest of the cylinders

When you have done all cylinders remove the drain plugs, reinstall oil pipe, bolt holding transmission filler pipe to head, fan shroud, valve cover, breather hoses, air filter housing, & electrical connector to intake hose

- Ron in SC

Valid XHTML :: Valid CSS: :: Powered by WikkaWiki

PeachParts, LLC all rights reserved 1999 -
PeachParts, LLC takes no responsibility whatsoever for any technical assistance offered by anyone. The Risk is 100% yours.