Source of Roto Caps 280SL

[Pawel66]

The roto caps seem not to be available at Mercedes (I see the red dot in the WebParts, waiting for dealer reply), neither SLS nor Niemoeller, which are my usual sources for parts.

Anybody has a source of them? This is A0000532135.

[cfm65@me.com]

Hi Pavel,
What is a roto cap?  Do you perhaps mean distributor cap? If so, it is probably best getting one from your local Mercedes agent or someone on this forum might be able to assist with a used cap.
Regards
Chris

[Pawel66]

Sorry, I was not precise, thank you for your attention.

Roto cap (valve rotator) is the bottom seat of the valve springs. It makes the valve rotate in its seat. Sometimes it gets stuck.

Other questions to the forum are:

1. Is it possible to make it unstuck? How?
2. Is it necessary to dismantle the valve assembly?
3. How to do it best without the head removal? I heard about compressed air or sticking some support through plug opening. My suspect valve is the exhoust valve, so simple support with the piston may not be enough...

[ja17]

There are vast quantities of good used ones around. They hardly ever go bad. Any Mercedes repair shop which works on these vintage engines should have lots.

[Pawel66]

Thank you Joe, sounds like a good tip!

Hope it applies here as well, we will look around.

[stickandrudderman]

A tip for removing valve springs without removing the head:
Position the piston about half way down it’s stroke (plug removed) and insert a very long length of string. Stuff it in as much as you can and then rotate the crank to bring the piston up and use the string to push the valves closed. You can then remove the springs without fear of the valves dropping into the cylinder. When you’re done simply pull the string out!

[Pawel66]

Thank you! Nice tip!

Good to leave one end of the string hanging out of the plug's hole probably? 

Sounds like this is the way to go.