Removing M42 head - problems?

[JR ///M5]

These are torque to yield bolts and are not to be re-used under any circumstances. When you are torquing them back, upon reassembly, you're gonna think those suckers are going to snap.

 I believe there was a recall on the head bolts on the early M42 engine. If they were hex head, then it missed the recall. The replacements are Torx.

JR

[kmack]

Well, I got the head off.  Only broke two bolts.  Both are sticking up out of the block so there is meat to grab onto.  Problem is, they are stuck good.  Someone had this motor apart once before and put what looks like Loctite on the threads of the head bolts (slightly redish, powdery substance caked on the threads).  I was told you are only supposed to lightly oil the threads.

Anyway, I'll be soaking them good for the next few days and then trying to wrench them out.

Also, my head had 3 cracks in it.  Time to start the hunt for another one.

[2002maniac]

Someone had this motor apart once before and put what looks like Loctite on the threads of the head bolts (slightly redish, powdery substance caked on the threads).

Doh!

Good luck getting those out. Red loctite is supposed to be semi-permanent.  Heat can loosen it.

[kowalski]

yeah, break out the ol' torch.

[kmack]

Well, the torch didn't work, neither did new vise-grips, and neither did the stud puller set that I bought.  The only thing the stud puller did was to continually break the bolts off about 3/8" at a time.  (These were a type of collar that is hammered onto the stud/bolt and the teeth inside the collar grab the bolt.)  They eventually broke just below the surface of the block.

So....I'm currently drilling them out.  Slow and painful process, but it has to be done right.  I have thread inserts I can use if I need to.  I'm hoping to not need them, but they are there as a last resort.  Had to stop in mid-process last night because of rain.

So much fun I can hardly stand it....

[RED IS 91]

That sounds painful
good luck with that .
I don't believe you told us why your pulling the head???
gasket??
Is the motor in the car ?? That sucks if it is ,being leaned over the fender gets tiresome.

[kmack]

I don't believe you told us why your pulling the head???
gasket??
Is the motor in the car ??

Well, it started as a cooling issue.  The car kept overheating.  At first I didn't  notice any significant coolant loss.  But later on, I did.  Then I found coolant in two cylinders.  That is what necessitated pulling the head off.  And, of course, I found 3 cracks.

Yes the motor is in the car.  At first I considered the idea of starting this procedure inside my garage, but that would have meant I had to park my 240Z out in the driveway.  And with the weather we've been having, I'm glad I didn't do that.  Unfortunately, it means I have to perform surgery outside.  Oh well...

Anybody have a M12 x 1.5 thread tap I could borrow in case I need to put thread inserts in?

[nickmpower]

you should have got 2 nuts and put them on the studs

[kowalski]

should have got a hotter torch.

[kmack]

I'm not sure a hotter torch would have worked.  There are very obvious signs of red Loctite on the threads and in the bottom of the holes that I'm currently drilling out.

And the two nut trick wouldn't have worked any better than the stud pullers that I used.  The stud pullers are basically a hex nut that is hammered onto the stud and grips it very tightly.  It twisted the studs off.

No worries.  I'm almost done drilling (will try to finish up tonight).  Once the threads are all clean and I get my "new" head, then I'll be back in business.

Curses to the idiot before me (PO) that gave me all these problems...

[2002maniac]

Should have hunted down the asshat that put loctite on your headbolts.

[kmack]

FINALLY!!!!
Well, I got my "new" head (new to me) this past Saturday.  Bert's Motorworks did a great job getting a used head rebuilt for me and at a great price.  Thanks Bert.  Saturday afternoon saw me trying to remember exactly how all this crap went back together.  (It's only been sitting apart for like 4 weeks!)  Finally got it all put back together on Sunday afternoon.  She started right up and is purring quietly.  Had a bit of condensation smoke out of the exhaust at first, but it went away and has not been back since.

I have not run it past 3500 rpm's yet.  Kind of a little gun-shy at the moment.  Has a lot to do with that stretching feeling from the head bolts.  I've stretched and broken enough bolts over the years to know exactly how that last moment before the break feels.  Felt just like that on the last 90* turn on the head bolts.    

And the realization that the exhaust manifold should have been put into the engine bay (or mounted on the head) before the head was bolted to the block.  What a fun chore that was....    But at least the car is running again.  

Thanks to all for all the help in this endeavor.