Join Date: Feb 2002
Location: N.W. Washington
i recently experienced a similar deal w/ my car, only it was a gradual rise always before, then one day it started spiking as you described. i assumed i had air in the system, and bled it off, only to have it start spiking again. that was just before my 34 year old heater core gave up the ghost on me, dumping its contents on the ground. when i disc. the core and bypassed it w/ a single hose to get it up and running again, it went back to a gradual rise to 180 again. my thoughts on the matter were the old core was sucking air and not allowing the system to operate correctly, untill it fully gave up. it only "spiked" a day or two before it let go, now all is well again. except i have yet to replace the core. thats a winter project. good luck, hope that helps!
[This message has been edited by 68rs406 (edited 10-25-2002).]