I’ve received a couple of e-mail requests for additional detail, so here it is.

First, you’ll need a manual to get the proper torque specs for your engine. Mine is a 300E 2.6, and it takes 21 N-m for the rocker stand bolts and 8.5 N-m for the valve cover bolts. Those were the only specs I needed.

The only tool I was missing was a 27 mm socket for turning the engine over. I used a 1 1/16 inch socket that worked fine with all the spark plugs out, but didn’t fit perfectly.

First I yanked the valve cover and the plugs. I pulled the distributor cap off so I could keep the wires routed in the valve cover and remove the cover, wires and cap from the car as an assembly.

Then I brought the #1 cyl to TDC on the compression stroke. Just look in the plug hole and you can see the piston come to TDC. Then look at the rotor – if it’s at about the 10-11:00 position, you’re there.

Pull out the 3 small bolts and remove the oil piping from the top of the rocker stands.

Pull the 4 bolts (13mm socket) from the rocker stand for cyl # 1. Wiggle the stand a little and use a magnet to catch the ball cups from the top of the spring retainer. Set these out carefully so you can put everything back where it came from. I used a flat piece of cardboard on the air cleaner to keep things nearby.

Pressurize the cylinder – see my note above on going slightly past TDC and holding the engine in place with a breaker bar.

Compress the valve spring (intake or exhaust first, doesn’t matter), rap it lightly with a very small hammer to un-stick the retainer from the valve stem. Use your magnet to pull the keepers out and lift the spring off.

Take the old seal off with a screwdriver or your fingers if you can. Be careful not to slip and scratch the valve stem. Wipe the little bit of sludge off of the guide with a lint-free rag. Smear some fresh oil on there afterwards. Give the valve stem a wiggle – fairly snug? Good, the guides are in good shape.

Take the correct seal (Exhaust valves are larger in diameter than the intakes), smear some oil in it to lube it for assembly, put the little plastic tube over the valve stem and slide the seal in place until you feel it pop into position. Take some needlenose pliers and remove the tube. Note: these tubes come with the seal kit. You’ll know what they are when you see them.

Reinstall the spring and do the other valve. Then remove the air pressure.

Stick the ball cups on the valves and reinstall the rocker arm stands. I ran the bolts down diagonally going a little tighter each time and then did the final torque setting with the torque wrench.

Here’s a trick…
Look on your valve cover for the firing order. Do the cylinders in the order of the firing order. That way you always know which cylinder is coming up to firing position next.

Major warning! Don’t drop any small parts or you’re screwed. Use your magnet and take whatever steps are needed to keep those ball cups and retainer clips under control.

Be patient and don’t do the job when you have a time constraint. By about the 3rd cylinder things are more routine and you’re cruising right along.

I’m really glad I did it. Okay, now I have to find something new to worry about!

Here’s a picture that should help. I was always wondering what the heck it was going to look like in there. In the picture I have taken off the rocker stand for cyl # 1 and have the spring and seal off of the exhaust valve. If you want the .jpg file so you can zoom, shoot me an e-mail.

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D.H.

04 ML500
02 E430

Experience is something you don't get until just after you need it.