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Discussion Starter #1
I pulled the sparkplugs and valve cover. All valves open up and don't look unusual in any way. However, on exhaust stroke, I notice the intake valves were opened about 1/4 of the way, before the piston fully reached TDC. Is this normal?? Seems a bit excessive as far as valve overlap goes. Could it be my timing chain jumped a tooth? Momentum from the piston and rods and then added heat expansion could, might, hopefully have had a piston tapping a valve? I did also notice a spark plug that looked like it had been melting. I only use premium fuel and never heard any pinging or knocking (till now)...What does the Alfa experts think about this situation?
 

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All I can offer is a melting plug is a potentially bad sign in regard to some sort of air leak. (not false air, but intake gasket, plenum to manifold or the like. Anything post-throttle body)

If the plug looks like that, then regardless of whether it's actually blown, it'll likely need a teardown as chances are high there is simular damage to the piston or valve.

If you could lay hands on a scope it would let you look around more deeply for sure.

:2cents:

If a piston was hitting a valve, I'd question the rods and/or pistons anyway, even if they appeared completely intact and undamaged.


Granted, the above is likely nothing you wanted to hear nor consilitory in any fashion, but not holding back to give a false sense of security.
 

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It's easy enough to check the valve timing. Turn the motor to TDC and the cam timing marks should line up with the marks on the cam caps. If that is OK, check the valve clearances. That should reveal a damaged valve.
A compression test can also give you some good clues.

Ed Prytherch
 

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Discussion Starter #4
I'm going to check the timing marks on the cam tomorrow, to see if everything is where it needs to be. If it jumped, I'll put it back where it should be and then do a compression check to see if a valve is leaking (from possible fist fight with piston-that bully!). If it seems good, she's going back together for another check. The only possible leak I found is from the air/oil separator hose.
 

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Discussion Starter #5
It's easy enough to check the valve timing. Turn the motor to TDC and the cam timing marks should line up with the marks on the cam caps. If that is OK, check the valve clearances. That should reveal a damaged valve.
A compression test can also give you some good clues.

Ed Prytherch
We think alike, although, you typed it 5 seconds faster...
 

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Sorry abpout the bad luck...I too almost suffered the same fate from a **** heater hose clamp but got the ignition off pronto. Very good chance the valves floated and perhaps contacted a piston or two with resultant bent valves. Assuming so, I'd pull the cams--do the valves close? If not, pull the head, lock down the liners & inspect the pistons & liners throughout their travel. Sounds like new valves might be in order as is maybe a complete head job...
 

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Discussion Starter #7
Sorry abpout the bad luck...
Thank you very much. I'm hoping the valves aren't bent, as I've mentioned before, I'm beyond broke, I can not afford anything in this point in time, including losing my job. As always though, planning for the worst while hoping for the best.
 

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The Nord engine timing chain has way too many links in contact with the gear teeth to jump, unless you built an engine and completely left the tensioner out. Sorry, but I just don't think that's a real possibility. On a V6 timing belt, sure, but not with that chain . . .
 

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Discussion Starter #9
The Nord engine timing chain has way too many links in contact with the gear teeth to jump, unless you built an engine and completely left the tensioner out. Sorry, but I just don't think that's a real possibility. On a V6 timing belt, sure, but not with that chain . . .
So the intake valve should already be 1/4-1/3 open on the exhaust stroke BTDC?? That seems like a God awful lot of overlap to me, VVT, could that maybe cause a problem like this?
 

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Book sitting here says intake opens at 24 deg 44 min to 17 deg 44 min BTDC and closes at 94 deg 28 min to 101 deg 28 min ABDC for Motronic.

24 degrees crank rotation is better than 1/8th turn at the crank pulley, so TDC should show a fair amount of valve hanging open, yes :shrug:

Weren't you doing cam timing or the like recently?

Any reason to think mabe the lock nut on the exhaust cam slipped, (didja put the tab in there and make sure the lock bolt through the gear was snug?), or the intake got degreed a little off, or not quite seated in it's degree teeth?
 
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