The vehicle is a Model W126, Engine 116.965, 420 SEL, 1986.

I'd like to know if it's normal to be able to rotate the distributor rotor by hand with the distributor mounted in the engine and bolted down.

I removed the distributor for changing the water pump and upon reinstallation I was startled to find that I could rotate the rotor by hand without manually rotating the engine. It made me wonder if I broke something.

Another question: The "Service manual CD" instructs that when the distributor is reinstalled it should be aligned as follows:

Position engine to ignition Top-Dead-Center (TDC). Insert and align distributor as follows: "fit on 90 degree angle to notch in the distributor housing edge. Align the markings on distributor rotor and distributor housing very exactly to each other."

I'm having trouble trying to figure out where this 90 degree angle with the notch is measured.

Thanks for any help

William, the distributor rotor should not turn by hand if unstalled correctly. I would not attempt to start the engine until you figure out what's wrong and correct it.

__________________
Fred Hoelzle

Thank you, Ferdman, for straightening me out. It's like a breath of fresh air when someone cares enough to respond.

With your response in hand, I went back and kept working with the distributor until I finally got it seated so that the rotor remained fixed. There is still some "play" in the rotor, meaning that I can move the rotor back and forth a little, but I'm assuming this is normal.

I think I've got the rotor positioned correctly but I'm still puzzled over how to check the 90 degree angle with the mark on the distributor rim that's mentioned in the "Mercedes Service CD".

Many thanks.

Use a socket and turn the engine via the harmonic balancer in the running direction; your distrib. should move. If ya don't have metric, I think that 1" socket fits good. When the mark is on "0", degrees from your pointer, the rotor should be pointing to the mark on the distributor. If it is 180 degreres off or backwards, pull the distributor up and rotate it 180. Once in, the copper piece of the rotor will be at, or v. close to this mark within the distributor housing. Also, this rotor position will be at the #1 position on the cap; which I think is marked. Hope this helps. les

Thank you Les.

What you had to say is very helpful and greatly appreciated. It's just what I needed to get the job finished.

William