I just replaced the valve stem seals on the 90 300E. With 166K, it has been using about a quart of oil every 1,000 miles, which isn't too bad. I haven't done valve stem seals before, so I decided to go for it. The parts are dirt cheap and why burn extra oil?

It was pretty easy with some advice a while back from Donnie and numerous posts by Larry and others on the subject. Thanks guys! I did have to buy a few tools. It took me from 9:00 pm (after the kids went to bed) until 1:30 am when I took my test drive and declared the job complete. This included a new serpentine belt and belt tension damper (little shock), but I spent most of the time on the seals. There’s definitely a learning curve involved, but by the time you’re about ½ way done, things are moving along pretty smoothly.

I bought a Craftsman 3/8 drive, in-lb torque wrench. It goes up to 250 in-lb and is perfect for this job. I didn’t want to guess at the torque values since all the bolts go into aluminum threads. I also got an overhead valve spring compressor. It was a “Powerbuilt” brand from Kragen. It worked okay, but I wished I had bought a better one. The last thing I got was a telescoping magnet tool (Craftsman) which I used to catch the ball cups when removing the rocker stands and also to pull the keepers out of the spring retainers. I temporarily converted my compression tester into a tool for hooking up compressed air to the spark plug hole to hold the valves in place. It worked great. I bought the seals and a new valve cover gasket from Partshop for about $20 total.

I’ll find out over the next couple of months whether this will help reduce the oil consumption. The old seals weren’t cracked or hard, but I could see that the sealing lips on the ID were worn flat.

The job wasn’t too bad, but is a bit of a back-breaker since you’re hunched over the engine the whole time.

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D.H.

04 ML500
02 E430

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