Cliff.....The large water jacket is a common problem area, but any of the smaller jackets can cause problems too

1 hour ago, Diseazd said:

Cliff.....The large water jacket is a common problem area, but any of the smaller jackets can cause problems too

I see something to read up on.  You're head bolt holes are threaded, mine aren't on that E31.  Is that something you did or do all P79s have that? Thanks!

Hi all. Thanks for your suggestions. Just got home from work.

I pulled the plugs and cranked the starter - sure enough, there is a whole lot of water in cylinder 6. So I guess it's the head gasket? If so, good news I suppose. Could be a lot worse!

I've always used quality coolant, but I've only had her for 5 out of her 35 years. The radiator was certainly full of plain old water when I took ownership. That said, the radiator was in fairly good condition and didn't run brown when I first drained it.

1982 280zx 2+2 non-turbo, auto in Melbourne, Australia

These engines are prone to detonation and detonation is a very powerful force in the combustion chamber that can cause damage.  When you advanced the timing you made detonation more likely.  Or, it's just got miles on it and it finally let go when you were hooning around enjoying the extra punch.  Pretty cool though, how these guys narrowed it down to the exact cylinder and details of what you would see, huh?  Wizards.

Now you can start a new thread soon, titled  "how do I remove this broken bolt/stud fragment from my head/block/whatever".  It will be fun.

10 hours ago, siteunseen said:

I see something to read up on.  You're head bolt holes are threaded, mine aren't on that E31.  Is that something you did or do all P79s have that? Thanks!

That's an F54 block not a P79 head   All blocks I've dealt with are threaded.....

59 minutes ago, Diseazd said:

That's an F54 block not a P79 head   All blocks I've dealt with are threaded.....

Egg on face.  Sorry

I looked at a head in my spare bedroom to see that water hole then looked at your picture.  Looking back those 6 cylinders are a dead give away. 

Still check the oil for milky condition.  You want that oil out of your motor ASAP if there is water in in.

I'll check tonight after work and if it's milky I'll drain it, thanks JSM. I'm waiting on a ballpark quote from a cylinder head specialist.

1982 280zx 2+2 non-turbo, auto in Melbourne, Australia