Hi I have 87 with a 3800 i put in this year . The problem i am having is the thermostat is bending in the modified fiero housing When i warm up the engine at idle the thermostat opens at 180 and runs ok then once i drive the car some times i find the engine temp does not get to 125f then i check the thermostat and the extensions on the thermostat are bent . Looks like there is to much pressure and blows it open when the engine is cold
I've had this same problem and have been chalking it up to crappy autozone thermostats. Happened again today. Busted the heater hose splice and was leaking,opened cap to top off after fixing and found bent thermostat.
Mine is an all stock 88gt basically. Looped the heater core till I had time to change out.
I do have a brand new champion radiator,but that is about it.
This has happened 3 times since i've owned the car (3-4yrs/2-3k miles) With original rad and heater core twice and now once with new radiator and heater core bypassed (under hood,not at housing). Water pump is new (<100 miles) as well.
What is the actual mechanism of how this is happening? Almost looks like the thermostat stuck and built pressure to bend it,which would make sense why the plastic splice broke (due to pressure?)
It has NO air issues and the system has been flushed at least twice since i've owned it. No head or lower intake gasket issues. Thanks for any furthur edumacation on this issue,I never put much thought into it other than crappy parts.
I always drill a 1/4 inch hole in the rim of the thermostat to let a little water bypas it, position the hole at the top when you put it in and it will let a little water and any trapped air flow through the system. Works for me. Larry
The water pump doesn't create enough pressure to bend the thermostat.
Check the pressure cap that covers the t-stat housing to be sure the inner rubber cushion rotates freely, if it is frozen in place it will twist the t-stat handle upon tightening, leading to the collapse. The t-stat handle should be slightly below the sealing ring of the housing when properly seated in the housing.
Look at the legs of the thermostat. The thermostats I have seen in the past come one of two ways.
Flat steel - cheaper way of manufacturing and usually found on the parts store brand units.
Bent down the length of the leg - this is what the genuine OEM units look like and the Stant units I have bought in the past. That slight bend adds a tremendous amount of stiffness to resist this buckling failure mode.