I have a beautiful 1987 Pontiac Fiero GT (original owner) which
(knock on wood) has rarely given me problems - but I a stumped now
(probably because I know next to nothing about auto repairs).
The problem is overheating as follows:
1) I fill the place (where the thermostat is housed - on the rear
engine) with a 50/50 mixture of coolant and water. This is done until
it begins to flush out from the radiator (I had already taken the front
radiator cap off).
2) I fill the Coolant overflow tank with coolant.
3) After about 5 minutes of driving with no problems - the heating
gaige "redlines" - I pull over and it is hissing like it's read to
explode. Please note: Nothing appears to be leaking because I always
check - I know the original water and coolant is still in there -
albeit probably turned to steam.
4) Since nothing was leaking - I assumed it was a bad thermostat so I
purchased another one - yet the same problem.
5) I replaced the water pump in 2004 (8,000 miles ago - I drive the car
very little) and replaced the radiator in 2001 (19,000 miles ago) - so
I would assume it shouldn't be one of those (I hope)
Can anyone give me some guidance on what the problem might be. ?
Thanks so much in advance.