As the title say can you change a head gaskets with the engine still in the car i think iv ask on here befor but i anit been on for a long time and i cant find the thread so i ask again ??
when taking the timing chain & cam spockets apart, always make either a note/photograph and or mark the position of the upper timing chain relative to the middle idle spocket and the 2 cam spockets.
losing track of this would require realigning the lower chain with the upper chain either:
*with the engine still in - a little tricky to access but still do'able, requires hand cranking the engine several times until the lower chain marker and idle spocket marker lines up,
*lower the engine to access the lower timing chain cover
*engine out job
make sure the head & block surfaces are clean, grease/oil free and flat with no intruding deposits. i used brake cleaner or isoprophol alchohol to degrease mine before assembly.
some patience, keeping parts organised and double checking helps
there's some helpful photos from my project in my blog.
caution: loads of pics