2.0 TS Head Gasket Lifetime
Wanted to get some facts and feedback about lifetime of headgaskets, I am building a case against a garage who changed the head gasket on my 2.0 156 Sportagon. The headgasket started leaking oil both outside the engine and into the coolant after 4 months (probably 4000 miles). There was no overheating in this time. The headgasket was replaced by another garage who checked the head and found no fault. Engine was put back together and car has been fine since.
[background to this is that the headgasket was replaced folllowing an engine rebuild under warranty by first garage - the timing belts they changed failed after 9 miles, its a long story]
My question is - how long should a head gasket be expected to last?
Also am I right in thinking that logically:
if engine has been put together by garage A and has a fault,
and if engine is dismantled and put back together by garage B using same parts (except head gasket belts etc).
Then blame for the fault must lie with garage a's workmanship
or am I missing something?
Grateful for all feedback