Author Topic: Valve rotator fail. What next?  (Read 202 times)

raueda1

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Valve rotator fail. What next?
« on: 02 October 2019, 07:47 PM »
Here's my latest discovery.  In taking apart the head for inspection etc I discovered the odd, circular scoring under a valve rotator.  See pic.  The rotator itself is undamaged and moves freely so obviously it's a replacement.  So what to do about the scoring?  Put it back together and ignore it?  Get it milled down a bit and put the rotator on a shim?  I've discussed it with Rumb who personally inspected it and he's stumped.  So am I.  speculations on the cause would be interesting but of greater importance is what, if anything, to do.  Thoughts welcome, as always. Cheers,
-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 rotator fail. What next?
« Reply #1 on: 02 October 2019, 09:46 PM »
This usually happens when the valve guide comes loose in the head.  I've seen it happen a handful of times on 4,6, and 8 cylinder engines.  Since the bottom of the rotator bites into the head and doesn't turn I'd just make sure the guide isn't loose in the head and put it all back together.  You mentioned that you thought the rotator had been replaced, even if it has make sure that the little knurles on the bottom of it aren't flattened or worn down.  They HAVE to bite into the head. (note the bite marks around the guide on the right side)  Otherwise this issue at hand will be present yet again. 
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Randys01

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Re: Valve rotator fail. What next?
« Reply #2 on: 04 October 2019, 02:15 AM »
....I'm guessing the heads have done a lot more work than the newer pistons.! ie the top wasn't overhauled when the bottom was.
Your rotator issue is tied in with your valve guides and possibly a few other suspects.
Time for professional opinion on the overall health of those heads..the guides..the valves themselves and springs ..the rockers..cam lobes.

raueda1

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Re: Valve rotator fail. What next?
« Reply #3 on: 05 October 2019, 10:20 AM »
....I'm guessing the heads have done a lot more work than the newer pistons.! ie the top wasn't overhauled when the bottom was.
Your rotator issue is tied in with your valve guides and possibly a few other suspects.
Time for professional opinion on the overall health of those heads..the guides..the valves themselves and springs ..the rockers..cam lobes.
I think you're exactly right. I may have an easier solution then rebuilding the head but it raises other issues.  Rather than getting on a tangent here I'll start a new thread. thanks and cheers,
-Dave
Now:  '76 6.9 Euro
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0