Combustion Gases in Water Jacket

[busbeagle]

Gentlemen,
I have an interesting problem.  My brother bought a 318i with a bad motor (broken cam, longer story).  4th E30 M42 in family.  Proceeded to have a different head rebuilt but decided not to have pressure checked as it came off a known good engine.  Used new gaskets, bolts, etc, bolted it all together and had compression gases in cooling system.  Torn it back down and found what we thought was a spot of sealant from the profile gasket area on the cylinder head gasket that I must have transferred there when I handled the head gasket with gloves on.  The machine shop and I concluded that this was probably allowing combustion gases to pass by the gasket.  Just to make sure I had the head pressure checked and it passed.  Made sure I did not repeat the error, cleaned everything, bolted it back together a second time with the same results.  So now the guessing games begin (at least for me, unless one of you can shed more light on this).
Next steps:
Call machine shop (which has done other M42 heads for me) and ask what pressure they check the head at
Questions:
1.   Could there be an undetected high pressure only crack in the head and has anyone ever seen this on an M42 head?
2.   What is the probability that the issue is that the head gasket has just not seated and has anyone ever had this issue with an M42?
3.   As a test if #2 is probable (and since the head may have to come off again anyway) what is the advisability of taking a few extra degrees of rotation on the stretch head bolts to try to get the gasket to seat?  If a good idea, how much?

Thanks
David Beagle
Seattle

[Cobra Jet]

Before putting the rebuilt head back on the block - did you have the top deck of the block checked to verify that it was not warped (and did you do the same to the bottom of the head)?

If the block deck or the bottom of the head is ever so slightly warped, the head gasket will never seal properly and therefore you could experience a possible failure, even w/ new gaskets, new head bolts & proper torque specs.

[nomad]

Yeah, did you resurface the head face and really clean the block? No gouges in the block or head surface?

Headbolt holes totally clean so you are getting the best torque and proper depth? Used the right head bolt washers? Installed the headgasket in the right direction? Crack in the block?

Just thinking out loud.

[busbeagle]

Head was checked and was flat and a clean up pass done over it.  Block was checked cleaned and is in spotless condition.  The next step is to pressurize each cylinder with 125psi of air.  If that does not show which cylinder it is leaking we will warm the engine and run it on an alternating 3 cylinders until we find which one is pressurizing the water jacket.  That will narrow down the location to look for a hot or high pressure only crack in the head.

When I get back to this in a couple of weeks I will post the findings

Thanks