what is a rotocap?
 

Just was wondering, what is the function of that bearing that sits underneath the valve springs, called a rotocap? What is the consequence if it seizes?

Thanks in advance for helping to educate me! :)

I think you're talking about the valve rotators. If so, the purpose is to turn the valve slightly, every time it opens & closes.
This results in a kind of " self-cleaning " action, lessening the chances of a minute piece of carbon holding a valve open.
If it didn't rotate anymore, you may never see a problem. ;)

Then again, the valves can wear out of round, giving you intermittant sealing and intermittant miss from no compression, backfires up the intake, etc.

Replace them if they are frozen, they are cheap.

Peter

Thanks for the info, guys!

Just wondering, is the rotocap standard design, or a Mercedes refinement?

Just about every engine has them except "standard" American automobile engines, for some reason.

Some American engines have a rocker arm design that is also supposed to rotate the valves for the same reason.

Peter

Besides cleaning, the rotocap keeps the entire diameter of the valve head a uniform temperature; thereby preventing warpage