What a pain in the ar*e that was!! After snapping one of the bolts while trying to replace the thermostat on my 164, it's taken me ages to sort it!
First, there's no access to the bolt (the one nearest the cam belt - a right carry-on just trying to remove the cam belt cover). Then, when I tried to drill the bolt out the hole was off center - arrgh!!
Couldn't remove the centre piece of the thermostat housing 'cos it's connected to the engine block by two rubber pipes, which are impossible to remove and couldn't remove the bottom bit of the housing because the bolts are impossible to get to!!! Who designs these things??!!!
In the end was forced to hack-saw off the protruding bit of bolt in-situ and best as I could drill it out. Then had to use a 6mm bolt that was longer than the original, so I could get a bolt on the end 'cos the thread in the housing was knackered! (Of course, the bottom of the thermostat housing isn't flat, so you need an extra long bolt just to be able to get a nut on it!!)
Anyway, lots of skinned knuckles, swearing, gasket sealant (and now alcohol
) later, it's done; moral of the story - don't snap a bolt when changing the thermostat!!!
Bloody Alfas - what is it about them that makes us put up with all the grief??!! (answer - starting it up afterwards and listening to the Alfa roar