1979-1993 & 94 Conv [Subscribe to Daily Digest] |
firstly not in the red or still in the green dosnt mean true overheating.. green means okay red means danger.. the two colours are there for a reason..
secondly the fact your expansion tank was nearly empty does not mean "most of the coolant was gone".. there is far more coolant in the system than whats in the expansion tank.. the system will also work perfectly okay with a nearly empty expansion tank.. so a nearly empty expansion tank dosnt mean bugger all except a leak somewhere in the system.. it could be a slow one or a fast one it all depends when u last checked it.. and it could be anywhere..
so as yet u have u have found a water leak nothing more.. it could be the head gasket it could not.. your car has not as yet really over heated there is nothing to suggest it has..
but cold cylinder compression tests mean bugger all with slow pressure leaks.. the leak comes from the very high combustion chamber pressures when the car is running under load.. cold compression testing will not show this up..
there are ways of finding this type of leak.. there will be pressure in the system when there should not be.. ie.. when your car is running well below coolent boiling point for example.. ie.. say one third or less up the gauge.. there should not be any noticable pressure in the system at this point.. another test is if your system still has pressure in it when the car has cooled down and been stood overnight.. again there should not be..
anyway i think u have a the beginnings of a pressure leak between cylinder and waterways.. your gasket hasnt yet "blown" but there is pressure leaking slowly into the cooling system when the car is running.. head gasket failures mostly begin this way.. saab gaskets dont suddenly blow they start with this slow pressure leak thing quite some time before the normal "symtoms" of a blown gasket show up..
typical symptoms at the begining are pressure in the system at all times even when the car is cold.. eratic temp gauge readings caused by small gas pockets forming around the t-sat housing.. and when cold and stood say overnight a few drops of coolant finds it way into a cylinder and shorts out a plug for the initial few seconds of start up.. this does not always happen thow..
the main point i make is that the "leak" only occurs at high running cylinder pressures.. the cylinder pressure are way way above normal cranking pressures of around 150 psi so normal compression testing or other lock down tests will not show it up.. this high pressure leak gets into the system when the car is running and can stay there all the time assuming an otherwise leak proof system.. if u still have a pressurized system when the car has been stood overnight its a sure sign of gasket failure.. or at least the beginnings of it..
i think your money has been wasted to be honest.. looking for pressure in the system when there should not be any or a simple exhaust gas sniffer test is the way to diganose this kinda leak.. nothing else will..
mind u being a saab owner and wasteing money does seem par for the course.. he he..
trog100
posted by 62.254....
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