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Discussion Starter #1
1976 Spider 2000. It has been running great but last week i noticed a little hesitation so i decided to check the timing. My mechanic friend had the timing light on her and I gradually climbed the rpms up to 5000. As the rpms climbed from 3500 to 4000 they suddenly dropped as i was putting down the accelerator. the engine then made a loud clunk and siezed at 2000rpms. We pulled the cam shaft cover, the chain was not broke. Plenty of oil in the engine and the wells under the cams, the cams are clean. Cannot rotate the engine even to TDC. Dropped the lower oil pan and the front of the engine looks fine. My brother, the original owner, suggested she may have dropped a valve. Should i cut the chain and pull the head? remember i cannot rotate the engine. or should i drop the upper oil pan, i read the threads and it sounds like a royal PITA...

Thank god she was sitting at home!

Please offer your advice.

David
 

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If you can't see anything obvious with the lower half of the oil sump removed I doubt removing the upper half will reveal anything.

Even with the spark plugs removed it won't turn - forwards or backwards?

If you remove the cam shaft upper bearings you can then remove the cam shafts without cutting the timing chain. See if any valves appear bent or guides broken.

Post some photos.
 

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Discussion Starter #3
Eric:

Correct the engine will not turn either forwards or backwards with the plugs removed.
 

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I will remove the cam shaft bearings and shafts. I was unaware i could remove them in this manner with the chain still attached. I will de-tension the chain first and wire it up so it wont fall into the engine. then remove the head.
 

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I would just pull the plugs for a look. If you don't see a loose valve...then just pull the entire motor. Were there any shavings in the lower pan? Tensioner for the upper chain still in place and locked into position? Lower chain intact? Just guessing, but it sounds terminal to me. No rotation forward or back is not a good sign.

Best Regards,
John M
 

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Discussion Starter #7
UPDATE! I just pulled the camshafts. The #2 bearing on the exhaust cam shaft froze and seized. I was able to remove the shaft the surface is heavily scored and the exhaust valve on the #2 piston is siezed. I plan on pulling the head tomorrow. Looks like it will need the head line bored and new camshafts and a valve....
 

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You may find it easier and more cost efective to just get another head.
 

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UPDATE! I just pulled the camshafts. The #2 bearing on the exhaust cam shaft froze and seized. I was able to remove the shaft the surface is heavily scored and the exhaust valve on the #2 piston is siezed.
A bad cam bearing wouldn't cause the engine to sieze at 2000 rpm. Even if the cam bearing locked up solid, the chain would break before it could transmit enough energy to abruptly halt the momentum of an engine spinning at 2000 rpm.

A stuck valve would certainly impact the piston, and explain that noise you heard as the engine shut down. Usually, the valve just gets mashed and/or prevents the piston from coming all the way to TDC. The crank will still turn back and forth, just not all the way around. I.e., the crank usually doesn't sieze after a piston-valve collision. However, sometimes a piece of broken valve gets wedged between the piston and liner, siezing things up. If so, the #2 rod could be damaged.

Now that you have the cams out and the chain disconnected, does the crank turn at all? Disassembling the engine is definitely in your future, but it's nice to diagnose things beforehand.
 

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71 Berlina 74 GTV 17 Giulia Q4
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It is possible that when the cam seized the bottom end kept going and sheared the small bolt that sets the cam timing. That will shear off long before the chain breaks. When that happend the pistons kept moving, came up and bent the valves. Check that bolt. Now the sixty four thousand dollar question is why did that journal stop bringing oil to the camshaft?
 

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71 Berlina 74 GTV 17 Giulia Q4
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yeah, something like that:)
depending on how badly the journal is scored you could take your dremmel with a flapper disc and polish the journal then apply some machinist dye and rotate the cam, find the high spots and take them down then when the cam rotates use some plastic guage and check the clearance and if it's in spec you can reuse the head or at the very least have a spare. one thing is for sure, you don't have anything to lose by trying it.
 

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Discussion Starter #14
UPDATE!

Just left the local Porsche mechanic. He indicated the head lost lubrication to the exhaust cam bearing causing it to seize and snap the small bolt on the camshaft cog causing it to lose time and bend the #2 exhaust valve. The scoring is minimal and they can polish out the head, bearing and cam shaft as well as replace the valve. He said i was lucky i was idling in my garage or i would have really torn it up....

Thanks you guys.

David
 

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Quick...
buy a lottery ticket !!
Very lucky guy. Can you tell why the cam lost oil pressure ?
 

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71 Berlina 74 GTV 17 Giulia Q4
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your'e welcome:) but you do need to fix the root cause.
 

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Discussion Starter #17
Do not know why it lost pressure at this time. He told me to clean out all the oil passages or it could happen again. I need to buy a good shop manual. vick auto has one for $29.95 has anyone bought this one? IAP has one but it is a CD and i prefer a book.

On my way to by that lottery ticket...
 

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71 Berlina 74 GTV 17 Giulia Q4
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Well since the head has to come off check the O rings as shown in the photo on the first page. If the 0 rings look ok and since you can't clean all the oil galleries unless you pull the crank for peace of mind you could take the upper chain out and with the liners held down crank the motor and see how much oil comes out of the gallery supplying the problem cam journal, if they all appear the same you'll know it's getting up there. Messy but worth it:) My money is on a deformed O ring. We're also in the perfect spot for the "while I'm in there itus" diease. Before you put the cams back on put the plugs in flip the head upside down then fill each combustion chamber with gas or mineral spirits and blow compressed air up each intake and exhaust port and check for bubbles. That is assuming of course you don't break it completly down and lap the valves. Good luck!
 

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David,

A friend in Louisville had a camshaft lock up, but at something over idle speed. The last time we talked, he had not disassembled the engine, but I will contact him to see if anything has been done recently

Are you an AROC member?. You can buy a copy of the full, loose leaf, factory shop manual from the library.

Do not know why it lost pressure at this time....I need to buy a good shop manual. vick auto has one for $29.95 has anyone bought this one? IAP has one but it is a CD and i prefer a book...
 

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Discussion Starter #20
I checked and there is a missing o-ring, so that may be the culprit. Thanks for the manual advice, sounds worth joining AROC just to get the manual...
 
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