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Dolfinz

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Ouch.  That might be the disaster you feared.  Even the valve seal came off.  Odds are high that the valve hit the top of the piston.  Hard to imagine a scenario where it didn't.

Pull that spark plug and see what you find.

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Be very careful messing with that. The valve lock is gone. So if you take the pressure off the stem, the valve's gonna drop into the motor. Would be interesting to put air to the cylinder to hold the valve up. If it stays up and holds air pretty good. i would reassemble it and run a compression test. These engines are very tough. My first concern would be a bent valve stem

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So,

the impression I get from Patcon is that there may be a way to reassemble this without pulling the head off.  I understand that the valve may be bent but it would seem to make sense to try it before going to the trouble of tearing the engine apart.  Any additional thoughts or suggestions?  I've never personally worked on the head so I have no clue if this is possible.

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2 hours ago, Dolfinz said:

the impression I get from Patcon is that there may be a way to reassemble this without pulling the head off. 

If you are super super lucky.  He's saying to find a way to hold the valve stem up so it doesn't drop in to the cylinder if the piston is down.  You could also rotate the engine to bring the picton up so that it will hold the valve up while you collect those parts that are scattered around.  Or you could remove the spark plug and fill the chamber with rope or tubing.  Many tricks.  Don't rotate the engine until you have a plan.

In the meantime - have you removed the spark plug yet?  If the electrodes are all smashed up that means there's been valve head damage and the head will have to come off.

You can also shine a light in to the hole to see if the piston is up.  You can learn a lot just by removing a spark plug.

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I did as you suggested.  I pulled the plug and the piston is up.  Not sure if it's all the way but I can see the piston head through the spark plug hole.  Also, there's no damage to the spark plug electrode.  Next steps?

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You're in a zone where you have to use some of your own gut feel.  If you have a piece of tube that will fit tightly over the tip of the valve you could slip that over the valve tip so that you can hang on to it.  Remove that rocker arm and see if you can rest the valve on the piston top without dropping it all the way in.  Pull the valve up and spin it to see if it's bent.  

Really though, you're just assessing damage at this point.  Even if you want to put it back together you'll need a valve spring compressor.  If you don't have plans to do the work yourself you might be best off to have a pro look at it and give you an assessment.  A pro with a bore scope could take a look and tell you there's piston damage, maybe cylinder head damage.  Today's borescopes are inexpensive and powerful.  You could learn a lot without taking it apart.

If the valve head had been destroyed and come apart I'd expect the sparkplug to have been damaged as the pieces bounced around.  It seems like maybe the valve took one hit, got bent, got stuck up in the guide, and the noise was the rocker rattling off of the cam lobe as the engine kept running.  You're most likely going to have to remove the head, it's just a matter of how much you want to do before making that decision.

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I was really trying to have to avoid it but considering this happened it's probably in my best interest to pull it and and have it inspected and repaired.  4 years ago it was a freshly rebuilt head I bought from Z Car Source here in Phoenix.  It sat in my garage for 3 years until I was finally able to start putting the engine back together about a year ago.  I had taken the lower end to a machine shop and had it rebuilt; since it was apart, shortly prior.  All I can figure is that all the time the head sat is why this happened.  I really can't see that it needs to be rebuilt again unless there was some type of damage to the head due to what's happened.  Question will be where to take it to ensure this doesn't happen again when I put it back together.  I'm open to suggestions on the best way to accomplish this.

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From the picture you posted, it looks like the valve is up.  Since they are loose, remove the springs and then see it you can grab the valve stem with your fingers and move it up and down as well as rotate it.  If you can get a good grip on it and can't move it, then you have a bent valve and piston damage at a minimum.  If you can freely move the valve up and down all the way and rotate it without the stem movingside to side, you might have gotten lucky.  Even if you did bend a valve, it's not always a total loss.  I've bent valves and simply polished the piston divots and replaced the valves.  If the head has gouges, it can be welded and reshaped.  It is also important to learn why the damage occured.  How much has the engine been run since it was rebuilt?  I know you said that you paid about $3k, but that doesn't mean the shop had any clue what they were doing.  I have built engines for half that and raced them.

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The engine doesn't have 2 miles on it.  I drove it about half a mile before it developed the starting/alternator issues.  Then I got it running and drove it 2 blocks and the rocker arm came off.  $1250 for the rebuilt head, $1500 to have the head and block put back together with timing chain and front end in place and a few hundred to a friends son who helped me put it the rest of the way back together.

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And the lubrication the machinest use isn't made to sit up. I think that's what happened to mine when I replied "sticky". I bought a head that was never picked up by the owner and although it was wrapped with poly and carboard on the valve end it was still tight or "sticky". I ran the oil pump with a drill on LOW speed and thought I had it worked out. Nope, lash pad came off on the first break-in drive.

There's no telling what caused that valve to stick but it did. I'll get in trouble for this but if the $100 headbolts just have one torque I'd reuse them.

You should find all the pieces if your gonna do it yourself. The valve keepers especially, there are small

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All kinds of possibilities:

The valve could have gotten sticky

The valve lock might not have been all the way in

Could have just been a fluke

I would have real hope if the spark plug wasn't trashed. The valve might be bent but shouldn't be cost prohibitive to get corrected

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45 minutes ago, siteunseen said:

A Harbor Freight boroscope thats images through your phone or "a real computer" like  @Zed Head capabilities of his you can stick it down the spark plug hole and give it a look. If that valve moves freely you may get lucky and not have separate the head?

Any Amazon wifi or bluetooth endoscope will work.  They are about $35 and most have a mirror attachment that allows you to see the top of the chamber.  I have the Depstech one and it works fine, though battery life on mine isn't great.  I just use an external battery so I don't have to worry if it's charged when I want to use it a few times per year.

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2 hours ago, Dolfinz said:

few hundred to a friends son who helped me put it the rest of the way back together.

Get this guy back on it.  He probably has the tools, maybe, or can help you figure things out.  

And, big picture, your grandson might get more out of completing your project than just driving it.  Who knows.

I see potential surface rust plus dry seals here...

3 hours ago, Dolfinz said:

4 years ago it was a freshly rebuilt head I bought from Z Car Source here in Phoenix.  It sat in my garage for 3 years

But don't see the need to pull the engine.

3 hours ago, Dolfinz said:

considering this happened it's probably in my best interest to pull it and and have it inspected and repaired. 

 

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First off, regarding my Grandson he's 8.  A little out of his attention span at this point.  As for what may have caused it I have an idea I'd like to throw out.  I don't remember the rockers being so noisy.  When it was running it almost sounded like a diesel.  Could it have been an oil pressure problem that made the rockers so noisy?  And caused it?  Without an oil pressure gauge I have no idea what the pressure was.  When putting the engine back together I replaced most everything including the oil pump.  Are the rockers noisier than I remember?  The engine isn't leaking any oil and the dip stick says full so I don't know why the oil pressure might be low.  Any ideas?

I think before I pull the head I'll get the scope and see what I can see first.  But then, depending on what I find I'm pulling the dash and getting the gauges working.  I'm certain for some reason none of them are getting their positive feed as my understanding from the wiring diagram is the sensors all route their connection from the gauge to ground.  They were all working prior to my rebuilding the motor.

Just to clarify, If I get the scope and see no damage odds are the valve is still bent right?  Wouldn't this still require pulling the head to repair?  However, if the valve doesn't appear to be bent or damaged then simply replacing the damaged components for this cylinder above the springs might result in the easiest solution?  I appreciate all the ideas and advice but trying to determine a course of action is difficult.  I really hate to dismantle the engine again.

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11 minutes ago, Dolfinz said:

If I get the scope and see no damage odds are the valve is still bent right?

Hard to say just from a visual. If the valve was really sticky I could see it being pushed up and sticking up without bending. You'll need to get a hold of the valve itself to see if it spins and travels freely or not.

11 minutes ago, Dolfinz said:

Wouldn't this still require pulling the head to repair? 

Yes

12 minutes ago, Dolfinz said:

However, if the valve doesn't appear to be bent or damaged then simply replacing the damaged components for this cylinder above the springs might result in the easiest solution? 

If the valve is not bent and the cylinder is okay then yea you could get away with new clips and retainer if they arent damaged. Although, I'm not sure how to go about replacing the stem seal. Someone with more knowledge can chime in if it is possible to do so with the valve installed.

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@Dolfinz, I have a boroscope, some extra unused valve stem seals that I'm hopefully never going to use, and the right size rope for filling the cylinder (if it comes to that). I'm in North Phoenix (~Tatum and Deer Valley), will PM you my phone number and we can talk. I'm about 10% as knowledgeable as the other guys who have been helping out, but I'm local and happy to help if I can. 

Word of warning: I'm not a Z whisperer, though maybe someday ...  Today, I did my first oil change on my own rebuilt L28, re-torqued the head bolts, and adjusted the valve lash. And now it idles and runs like crap. I'm hoping that I just don't yet have the "feel" for my feeler gauge and that I just got a couple of intake valves a little tight. The ups and downs of Z-itis. 

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I agree. You need to try to move the valve by hand, like Jeff and others recommended. If it moves freely I would reassemble it and run a compression test. If all the numbers look reasonable,  run it. After verifying oil flow and valve lash!

Pogden's help would probably be good.

Did you check valve lash before startup?

Did you verify oil flow at the rockers before startup?

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31 minutes ago, Dolfinz said:

I will try reaching out to Pogden but I have 2 questions.  How do you check valve lash and how do you verify oil flow at rockers before startup?

You check valve lash with a feeler gauge, but it requires you to turn the engine. I wouldn't worry about that until you address the issue with the valve that lost its keeper.

To verify oil flow, what I like to do is fill a oil can with 10w30 or your favorite flavor. Take the coil wire off the distributor. Hook up a remote to the starter. Make sure the car is out of gear. Take off the valve cover. Put a generous amount of oil on each cam lobe so there is some initial lubrication for each rocker. Trigger the remote starter and look for oil to come out of the spray bar.

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48 minutes ago, Dolfinz said:

What is a stem seal?

It is the orange rubber piece in your last photo. This goes at the base of your valve in the head to block oil from seeping into your combustion chamber. Example:
Valve Stem Seal Set OEM 240Z 260Z 280Z 280Zx | Z Car Depot Inc

 

This isnt a 280z exactly but it will give you the idea of the order of operations 🙂 :

stem.jpg

Edited by Barefootdan
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