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Broken Rocker or something worse?

See the pictures.

Do rockers actually fail like this or is it more likely that this is a symptom of something more - something I may have caused after doing intake system maintenance?

Background...
It happened right after reinstalling my entire CIS. I had it all off to replace the airbox, all the way down to the intake ports. The engine ran well for about 10 minutes as i was dialing in the mixture and setting the timing. Then the engine started making a loud clacking - I was pretty sure it was something major. Now I'm torturing myself thinking i may have allowed something foreign into an intake port.

It's a 78 911SC Euro-spec. I've owned the car for 30+ years. She has 350K miles and the last rebuild of the engine was around at around 185K. For the past few seasons I've noticed a clicking from around the #1 intake. I figured it was just a valve out of adjustment, but could this have been a weak point for some time?

Either way, i know i have to replace the rocker. I'd attempt that myself, but I'm worried there's junk in the cylinder. Any advice on how I could determine that? Other thoughts on what to do?

Ugh, I'm torturing myself thinking i may have allowed something foreign into an intake port. I had them all blocked off with wadded up paper towels and I'm pretty sure I visually inspected all of them before I started to reassemble, but I'm second-guessing myself. What should I do?


Old 05-06-2016, 05:57 PM
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Foreign material.......

Inspect the affected cylinder. I had a similar incident several months ago when I unknowingly dropped an intatke runner nut into the combustion chamber. Valves were bent. Had to remove the cylinder head and brought to the machine for new valves.

And to get the damaged cylinder head out, would mean more work. Almost half of the engine has to come apart and reset the cam timing and sprocket alignment. What a pain caused by a small foreign material. Btw, my broken intake rocker looks like yours.

Tony
Old 05-06-2016, 06:55 PM
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any way to inspect the cylinder without disassembling?
Old 05-06-2016, 07:16 PM
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pub911,
Buy a bore scope. These units are quite affordable now.
Old 05-06-2016, 07:34 PM
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^ Agreed on the bore scope. $36 for one that attaches to an iPhone. But I'm wondering if a steerable version might be a requirement. Makes no sense to get into the cylinder and have blind spots. Articulating scopes are much more of an investment.

Pub911... know the feeling---beating self up. Nothing to be gained from self torture! Let that sh** go and get on with repair. The positive side is you'll gain more knowledge from this. All said with respect for your situation.
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Old 05-07-2016, 06:04 AM
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Broken rocker arm is typically due to either metal fatigue or valve contact with something in the combustion chamber (i.e. piston>valve>rocker). Anecdotally, more of the latter.

Inspect the combustion chamber with a bore scope or equiv.;

Inspect other valve train parts carefully, including the cam chain, sprockets, valve springs and chain ramps, even cam timing.

If okay, rotate engine manually and feel/listen for abnormal feedback.

If confidence is strong, back off the rocker adjuster on the other valve and test cylinder compression, first by rotating manually, then with the starter.

If compression is consistent with other cylinders, I think you're good to go with replacing the broken rocker.

Sherwood
Old 05-07-2016, 09:03 AM
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That really looks like a foreign object in the cylinder kept the valve from opening, breaking the rocker. Sorry.
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Old 05-07-2016, 09:13 AM
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Scope due the mail today. Manual rotation by turning the fan pulley seems to bind at the Z1 mark, consistent with #1 rocker breaking, but it does turn thru the full 720 degrees. I notice a very very faint 'click' when it do so. Using the starter also seems to produce a slight click. I'm not going to push it any further until i get a scope down there.

A question about the rocker...the foot has play. When I pull the foot straight down in the opposite direction of the adjustment screw, there's a noticeable about of up-and-down play in the ball/socket. When the car was running for say, the last 50K miles, there has always been a tapping around #1 - the left bank, anyway. I had always attributed it to a bad valve adjustment and dismissed it since the car ran really well. Could this be related to my problem?

I know this question would be inconsequential if I find something in the bore, but as I stare out the window awaiting the scope, I can't help but hypothesize. Thanks for entertaining my thoughts and for the solid advice.
Old 05-08-2016, 06:42 AM
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Quote:
Originally Posted by pub911 View Post
Scope due the mail today. Manual rotation by turning the fan pulley seems to bind at the Z1 mark, consistent with #1 rocker breaking, but it does turn thru the full 720 degrees. I notice a very very faint 'click' when it do so. Using the starter also seems to produce a slight click. I'm not going to push it any further until i get a scope down there.
.......
DON'T USE THE STARTER!!!!

I'd do a leakdown, will reveal bent valve(s)
Old 05-08-2016, 06:58 AM
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DON'T USE THE STARTER!!!!

I'd do a leakdown, will reveal bent valve(s)
I must concur. Perform a leak down test before any active compression test.

Remove chain box cover(s) and valve covers and observe while manually rotating the crank.

Sherwood
Old 05-08-2016, 08:27 AM
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leakdown test tell's the story if valves are bent The way to go
Old 05-08-2016, 08:47 AM
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Inside #1 cylinder - two videos...
https://www.dropbox.com/s/6izcbd56h5r17r8/Record_01.avi?dl=0
https://www.dropbox.com/s/l7fz9nc3gov7y4l/Record_02.avi?dl=0

even if you don't have feedback on the condition, please confirm the links are working. Thank you.

Last edited by pub911; 05-08-2016 at 08:57 AM..
Old 05-08-2016, 08:52 AM
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Links work great. Hard to tell from the videos, though.
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Old 05-08-2016, 09:26 AM
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Check out the first video "Record_01.avi" at 0:40 thru 0:56. Is that a hex nut right about dead center of the piston crown?
Old 05-08-2016, 12:14 PM
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Quote:
Originally Posted by pub911 View Post
Check out the first video "Record_01.avi" at 0:40 thru 0:56. Is that a hex nut right about dead center of the piston crown?
No, it's not.
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Old 05-08-2016, 12:19 PM
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While i'm waiting to get my hands on a leak down tester, I continue to snoop around inside #1 with a borescope. Take a look at theses two new videos and help me answer a few questions:
What the heck is that "X" shaped image that looks like it may be bare wire?

And should the cylinder walls be coated in shiny black oil like what you see? FYI, holes 2-6 don't look that way....so what might cause it in #1? blown rings?

If not a foreign object, what else might cause oil blow-by and a broken rocker?

And i don't know about you guys, but i didn't see a valve mark on the piston crown....unless it's covered in oil, i see no sign of contact with a valve.

https://www.dropbox.com/s/yv3xoz9ne6nbtzy/Record_04.avi?dl=0
https://www.dropbox.com/s/qe7ysy648vt6nqt/Record_05.avi?dl=0

Thank you for your help.
Old 05-08-2016, 02:08 PM
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No, it's not.
Thanks, Pmax. Do you have a pic looking straight down?
Old 05-08-2016, 02:08 PM
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Videos aren't very revealing. How about comparing with another cylinder?
Old 05-08-2016, 02:33 PM
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That looks like the result of what ever is in there scratching up the cylinder walls.
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Old 05-08-2016, 02:36 PM
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Quote:
Originally Posted by pub911 View Post
Thanks, Pmax. Do you have a pic looking straight down?
No. I just got that pic off the web. The top of your cylinder would look like that with just some different contours of the head.

Your new video shows the X in cyl #1 which is clearly not normal !
That looks like a crack.
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Last edited by pmax; 05-08-2016 at 02:49 PM..
Old 05-08-2016, 02:37 PM
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