Author Topic: Valve rotators - what's inside and whether to replace?  (Read 456 times)

raueda1

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Valve rotators - what's inside and whether to replace?
« on: 21 October 2019, 10:26 AM »
In another thread I noted that the seat under the valve rotator was scored/grooved per the first pic.  The second pic shows the bottom of a rotator.  The little tangs fit into the notches on the head so the bottom can't spin.  It looks like, for whatever reason, a rotator seized and cut the groove.  But if the rotator seized then what;s making it all rotate to cut the groove?  I dunno, another MB mystery.

Anyway, that lead me wonder what's inside a rotator so I cut a couple open to find out.  See third pic.  Basically the bottom piece loosely seats against the head.  On top of the bearings is a grooved thrust washer, then another washer and finally the cap.  The springs rest on the cap.  Somehow this design rotates the valve. 

OK, very nice.  But doing this lead me to cut open 2 rotators.  The first one was a failed attempt, but I later noticed that it was very dirty inside, filled with junk.  However, it felt smooth when rotating by hand. I couldn't feel a difference between the 2 before cutting them open, so now I'm worried. 

When doing head work is it advisable to replace rotators?  Seems like we don't hear much about them and cleaning doesn't seem very feasable given their semi-sealed design .  The part # I found is 000 053 16 35 but I can't find it in the usual places.  In fact, I couldn't find any 70's era rotators at all (though I didn't kill myself looking quite yet).  Seems impossible, I must be doing something wrong.  As usual, comments and advice would be helpful and welcome.  Thanks,
-Dave
Now:  '76 6.9 Euro
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0

UTn_boy

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Re: Valve rotators - what's inside and whether to replace?
« Reply #1 on: 21 October 2019, 12:39 PM »
You likely won't find any of the rotators easily for a few reasons.  They rarely go bad/need replaced, and they haven't been available new in many years.  In my mere 25 years of working on these I've never seen one go bad, nor have I ever renewed any of these when rebuilding an engine.  They seem to take an inordinate amount of abuse and always seem to come out on top.  They're sole purpose in life is to turn the valve every time it opens and closes so the valve seat to valve face is uniform.  Though, note the springs and balls inside of the rotator.  These are to allow only one direction of rotation (when under spring tension).  They can be cleaned by soaking them in a solvent (acetone, methyl ethyl ketone, gasoline, etc) with the occasional agitation.  Use an air hose to blow out the solvent and debris. After cleaning, soak them in oil so they're lubricated. 

So, no.  It's not advisable to renew them since they rarely go bad, but mostly because you can't buy them new anymore.  But cleaning them is certainly a good idea. 
1966 250se coupe`, black/dark green leather
1970 600 midnight blue/parchment leather
1971 300sel 6.3, papyrus white/dark red leather
1973 300sel 4.5, silver blue metallic/blue leather
1976 280s astral silver/blue MB Tex
1978 450sel 6.9 Euro, Anthr/velour

raueda1

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Re: Valve rotators - what's inside and whether to replace?
« Reply #2 on: 21 October 2019, 01:42 PM »
You likely won't find any of the rotators easily for a few reasons.  They rarely go bad/need replaced, and they haven't been available new in many years.  In my mere 25 years of working on these I've never seen one go bad, nor have I ever renewed any of these when rebuilding an engine.  They seem to take an inordinate amount of abuse and always seem to come out on top.  They're sole purpose in life is to turn the valve every time it opens and closes so the valve seat to valve face is uniform.  Though, note the springs and balls inside of the rotator.  These are to allow only one direction of rotation (when under spring tension).  They can be cleaned by soaking them in a solvent (acetone, methyl ethyl ketone, gasoline, etc) with the occasional agitation.  Use an air hose to blow out the solvent and debris. After cleaning, soak them in oil so they're lubricated. 

So, no.  It's not advisable to renew them since they rarely go bad, but mostly because you can't buy them new anymore.  But cleaning them is certainly a good idea.
Thanks, that's great, super helpful.  I feel bad wrecking a couple of them.  But it makes me very happy to have a nice supply of spares.  I'll clean 'em, for sure. 

Any thoughts on how to deal with the groove on the head?  It's quite shallow.  I was thinking about taking a thin Alu washer and whacking the sacrificed rotator bottom on it to recreate the little ticks.  Then put it on the head and use a small punch to hammer a few dimples through the washer into the head to prevent it from rotating.  This would add a mm or so under the springs but my springs a very slightly compressed anyway.  I'm sure there are better ways . . . . .    ???  Cheers,
-Dave
Now:  '76 6.9 Euro
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0

TJ 450

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Re: Valve rotators - what's inside and whether to replace?
« Reply #3 on: 21 October 2019, 05:58 PM »
You could use an ultrasonic cleaner to clean the rotators. With the groove, I wouldn't worry about it, but what you could do is displace some material with a punch around the circumference in case you are concerned about the whole thing rotating.

Are there any signs of the valve guide moving at all?

Tim
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1969 300SEL 6.3 1394
2003 ML500

raueda1

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Re: Valve rotators - what's inside and whether to replace?
« Reply #4 on: 22 October 2019, 08:30 AM »
You could use an ultrasonic cleaner to clean the rotators. With the groove, I wouldn't worry about it, but what you could do is displace some material with a punch around the circumference in case you are concerned about the whole thing rotating.

Are there any signs of the valve guide moving at all?

Tim
Thanks for the comments.  No signs of valve guide movement and guides themselves seem OK.  The shop said that valve & valve seat faces were a little worn.  They propose the absolute minimal possible grind and leave guides alone.  I'll get an update ina day or 2 after more detailed examination.

I too was thinking about the ultrasonic cleaner and I've got a pretty big one with heat.  It's a miracle how clean stuff gets using one of those "citrus" grease removers at 50°C.  My procedure is ultrasonic dip till clean, then water rinse/flush followed by acetone (displace the water), followed by air blast, followed by brake cleaner (removal of any lingering organics and further drying), possibly followed by WD40 spray, Boeshield T-9 or motor oil depending on the part.  Cheers,
-Dave
Now:  '76 6.9 Euro
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0