sure, a little sweating here and there is fine.

for me, the moment i smell something through the heaters, then it is time for action.

Congrats on fixing the leak.

A long time question I have is what causes the head bolts to loosen on the SC's and whether this is specific to post rebuild checks. Did the factory specify tightening head bolts as a regular maintenance item ? ... is another related question. Haven't gotten consistent answers from the experts here so far.

Are these regular steel bolts ? What was the tightening torque ?

pmax..911SC heads do not get loose by them self.Only if the mechanics who do the valve job or engine job..follow the procedure and re torque the heads after 1000 miles....
Then the heads will not go loose..

Ivan

OK, would the loosening mechanism be some sort of "lengthening" of the new bolts ? Otherwise, how would the post rebuild be different from regular usage ?

This is just pure speculation on my part so hold the arrows !

if you just do the valve job ,no reason to replace the case studs.. the correct procedure is ...one must retorque the heads in 1000 miles...no other way to it
i am not metallurgists but it has something to do with metal settling down....

...most of the oil leaks on 911 is due to the mechanics...911 do not leak oil ,in my book...that also takes the correct maintenance..


Ivan

That makes sense to me as well. Are some types more susceptible to loosening ?

i don't remember exactly but i think i went for the stock 'upgraded' studs. all steel i think.

Yeah, it's a bit weird, passengerside all loose, driverside all tight.

The rebuild (split case job) was done by a specialised company, quite expensive too. Not really Porsche speciality (even though of course they did aircooled lumps before me), but overall rebuilding of engines.

Judging by how detailed they did the outside without me asking for it (cleaned and painted the cooling metal plates, drilled and retapped all rusted holes, replaced exhaust studs, all holes nicely plugged with plastic plugs, etc) then i think they should have done a very good job on the inside as well.

Redid half of the valve job now, all clearances seemed to be in the ballpark...maybe piece of carbon on one valve screwed up my settings? Engine ran perfectly while warming up, and suddenly one (or 2) cylinders stopped firing. Tomorrow other half. we'll see.

Weird indeed, it seems to indicate some cause other than the metal "settling". I would expect both banks being affected similarly if that were the case.

Let's hope not, considering there aren't any head bolts there in the first place (studs and nuts, like you, pNutz!). Yer welcome!

Definitely not a stud and nut guy here ! Yes.

wreckah..by saying you are doing a valve job...you mean valve adjustment correct?
Why do you do one side at the time?Also make sure your valve adjustment is not tight that would answer your missing cylinder no 2.....

Ivan

hi Ivan,

i did half because it was 12 o clock at night, did the other half in the morning. Anyway, don't think it had anything to do with valve lash...

think i found the issue: distributor vacuum advance is stuck in the advance position i think, that would explain my shifted timing issues, and slight misfires and losing spark. time to break out the dizzy.

and i do half and half with the car tilted over one way or the other, so i don't lose 2 litres of oil each time i take off the bottom valve cover :)

got the distributor vacuum advance/retard ring loose, vacuum pod is loose, so should not affect anything anymore, checked timing, (5 BTDC idle, 30 BTDC at 6K) but still i'm losing cylinders 2 and 6 when the engine gets warm...hmmm stumped. maybe i damaged the spark plugs lead caps pushing them on and off the plugs?
gonna measure compression now.

compression 190 psi on all of them, so nothing wrong. Still keep losing cyls. 2 and 6 when warming up. gonna get new plugs tmrw, see if that does anything. All plug leads are 4K Ohm. They 'click' nicely on the plugs.

Fueling might also be off, becaue i have been road tuning the last couple of months with loose-headstud-less-compression, so might be filthy rich now.