headgasket gone??

took the R for a play today, brang it on boost untill about 7k, come off boost and cruised for about half a mile,all was fine, pulled into my road and noticed a sudden puff of white smoke, car started sounding abit rough, pulled into my garage and head tank was overflowing, straight away done a comp test and 1 and 2 are 5 1/2 bar and 3 and 4 are 11, im pretty sure ive spat abit of headgasket out, it hasnt been off in a while. bores are wet too.. not oil

main question is can i get the head off with engine in car, i know its mainly inlet thats problem. what headgasket shall i go for? i think im gona stick to standard nissan unless i get a different answer. gona rebuild head while it out. let me know what you think

cheers
 
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pulsarboby

Guest
try compression testing it with no 2 plug left in head and with it removed, and fitting comp tester to no 1 cylinder.

if compression raises with 2 plug fitted but drops with 2 plug removed then you 100% know that it has blown between the pots on those 2 cylinders, as pressure cant escape from no 2 plug hole with plug fitted!
 
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pulsarboby

Guest
i find it quicker to drop the lump tbh, but then again i got big mitts and find it difficult to get my hands in those awquard places, without ripping lumps of flesh off lol.
if you can get your hands under the manifold and the Y bracket is removed then it will be quicker to just remove the head with engine in situ.
 
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pulsarboby

Guest
yes that is technically true karl but due to the fact that no 2 is last in the firing order the pressure on no1 cylinder will already have built up in the comp gauge and you obviously wont lose that pressure once its in there if you know what i mean!

ie 1342 firing order, when 2 is on compression this will feed pressure back to no 1 cylinder which will happen a few times if you did a 10 second crank to gain compression.
but if the plug is completely removed then the pressure will immediately escape from no 2 cylinder whilst you are comp testing no 1, which is how you can tell if its blowing between the pots or to a waterway!
 
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