1979 SC Chewed a Valve - Total Rebuild

[OsoMoore]

My SC chewed up one of its valves and jammed a cam. I was roaring out of a light (as I usually do) and heard a bang bang as I neared redline in first. The noise quickly stopped and it was time for a tow-truck. Car history at the end of this post.

Now it is all out and apart, and ready to teardown in earnest. I'll post here as I make progress. The two goals are:

1) Determine why it broke.
2) Prepare it for many years of excitement.

Current state is down to the long block and cam covers off. I've fished a good number of metal bits out, and more fall out each time I rotate the engine. I'm working on acquiring the Stomski tool to remove the cam shafts, so in the meantime I'll probably clean up removed parts.

Any ideas on what to watch for, measure, and photograph along the way are appreciated. I'm bagging and labeling each thing as it comes out, and have 6 bins labeled for each cylinder's parts.

There was a lot of oil in the heat exchanger for bank 4-6. Also some oil flooding when looking down those valves.

Photos of current state:




Videos from yesterday (before cam covers came off)
Video from the top. Three is the boomed cylinder.



Video from the bottom.



History!
This car has 280K miles on it. Originally a California car, its first owner was a female doctor who put 200K on it in 20 years, and then sold it to an Air Force mechanic, this forum's very own Leland Pate (https://forums.pelicanparts.com/members/1761.html). He is a big SC fan and founder of the 911 SC World Domination Plot and Dr. Pate's 101 Tips.
He rebuilt the engine and made performance improvements (head studs, larger bore, higher compression, etc). You can see his many rebuild posts on this forum, as well as his eventual sale post. Third owner was an occasional Pelican, and also sold it via this forum to me.
I'm the 4th owner, and it became mine in 2012. Since then I have made lots of small and moderate fixes, including transmission rebuild, CIS rebuild, fuse box, and fuel lines. But this is the first time in the block.

All things considered, it should have lasted a good many more miles before a rebuild. I hadn't adjusted valves in a few years, I'm not sure if that could have been a factor.

I feel fortunate to have 25 years of posts (the forums records don't go past the year 2000), and hope to make many more years of posts.

[OsoMoore]

Any recommendations on what to use or not use to clean nasty parts? I have some Simple Green, but I'm concerned about de-oiling things that should stay oily, and possibly opening things to rust.

[Flat6pac]

I soak in safety Kleen, scrub brush.
Dry parts, spray with Sam’s club degreaser, undiluted.
Power wash, respray the tough corners
Bruce

[stownsen914]

Ugh sorry to hear. The intake valve guide boss and the rocker are broken, and the retainer is missing. Hard to tell which happened first, but the dropped valve hitting the piston will make some noise for sure. Let's see what the piston looks like. Hopefully the rod and crank will just need to be checked.

[stownsen914]

As for preserving steel/ferrous parts after cleaning, spray with some WD40, or better yet dunk in a 50/50 solution oil and mineral spirits. Oil works too of course, just a little messier.

[OsoMoore]

Originally Posted by Flat6pac

I soak in safety Kleen, scrub brush.
Dry parts, spray with Sam’s club degreaser, undiluted.
Power wash, respray the tough corners
Bruce

Originally Posted by stownsen914

As for preserving steel/ferrous parts after cleaning, spray with some WD40, or better yet dunk in a 50/50 solution oil and mineral spirits. Oil works too of course, just a little messier.

Sounds good, I'll make sure to finish them off with some oil.

[john walker's workshop]

Probably had a tensioner failure. The cams are in different positions.

[OsoMoore]

Originally Posted by john walker's workshop

Probably had a tensioner failure. The cams are in different positions.

Interesting, I didn't think of comparing cam positions across the two banks. Is it indicated by orientation of one of the nuts at the end of the cam? Or based on the valve positions in the video?

There is a bolt (I think from the valve adjustment) jammed in the 1-3 cam by where it came off at cylinder 3. Could it catching there slammed it out of synch?

If there's anything I can look for now or during teardown to get more info, I'm eager to learn more.

[OsoMoore]

The failure happened while I was accelerating out of a light, and it banged for a few seconds before going silent. It sounded a bit like something had gotten loose on the exhaust, and I was in a tunnel with construction and no place to pull over, so I had been hoping to keep it limping until I was clear.

If a chain jump was the first failure, would it make the banging/rattling noise for a few seconds until something else went wrong?
Or could the chain jump be the second failure, caused maybe by the broken bolt jamming the camshaft?

[OsoMoore]

Took of the sump plate and took a few more pictures of the boshed valve. I think I can't do much more teardown until the Stomski tool arrives later this week. Is there something else I could do that I haven't thought of?

So probably the next few mornings are cleaning already removed parts? I guess I'll get a pair of buckets going and dig out my giant yellow gloves. Should I expect to be reusing hardware? Or just assume I'm going to replace all the bolts and washers?

Also, this funky yellowish thing came out during one of the turns I rotated the engine on the stand. It seems almost like ceramic.


More pics of the bombed cylinder valve/cam. Note the little nut jammed in there under the cam.



Nothing unusual to my untrained eye under the sump plate.


Best pic so far of the inside destruction.

[OsoMoore]

Watched another video. Maybe I can remove the tensioners now before cam tool arrives? Don't want to lose track of some evidence such as John Walker's note about cam misalignment.



EDIT:
This guy removes the valves before taking off the cam nuts. Maybe I can do that next and learn something.

[draw]

Wow, looks like a grenade went off in there! Bummer!

I think I see a swivel foot, piston ring pieces, and a piston circlip came out the bottom?

Good luck!

[Henry Schmidt]

I would guess (with data and pictures supplied) that the last builder used the intake valves beyond their service life. Even with hard impact, you generally don't see the valve head separate with a clean break.

[dannobee]

They also had that "bad batch" of valve springs where the outer spring would break. I'm rebuilding a 78 right now that had 3 broken outers. If they were original and never replaced, those little ticking time bombs are still in there.

Especially since he was near "redline in first."

[OsoMoore]

Lots more to learn inside, I'm sure. I am thinking about taking another set of good photographs, then working on removing tensioners and such while waiting for the tools.

I also need to peruse Wayne's book to identify what other tools I should track down.

[john walker's workshop]

An impact wrench and 46mm socket gets the cam nuts off. Don't need the Stomski tool for that.

[OsoMoore]

Originally Posted by john walker's workshop

An impact wrench and 46mm socket gets the cam nuts off. Don't need the Stomski tool for that.

Thanks John, I picked up the socket cheap, should be here tomorrow. I'll have the Stomski for reassembly.

[OsoMoore]

I went ahead and removed the rockers while waiting for the tools to handle the cam shafts themselves. I was especially interested in cylinder 3's intake valve, as that is the one that blew up.

I did note some minor wear on a few other rocker feet, specifically 4 and 6. I'm not sure if that is relevant and merits posting the photos.
This post I'm going to focus on the damage around cylinder 3.

First two photos, you can see the broken rocker arm and the jammed adjustment bolt stuck in the housing between #3 intake and exhaust. Not sure if that constitutes destructive damage to the housing. There's the bolt that jammed, and it has bent the oil supply line (or whatever that is).


Down here you can see rod that the rocker rides on had actually worked itself a good bit out of center. Maybe that was part of the issue? Or maybe it was an effect after the collision occurred? The shock was strong enough to flatten the head of number 3 spark plug and knock the wire off its connector to 3 as well.


Here you can see the removed parts of the rocker and the valve. The head itself is somewhere deeper inside. note the wear on the base of the valve stem, and some damage on that ring's edge as well.



Finally, here is the destruction inside at the base itself. I presume that damage is on the cylinder, and not on the cam header assembly? I fear a lot of damage has been done.

[OsoMoore]

And here's the walk-around video for this side.

[pmax]

Originally Posted by OsoMoore

Also, this funky yellowish thing came out during one of the turns I rotated the engine on the stand. It seems almost like ceramic.

What's the deal with the texture on the yellow thing ?