Coolant not coming to temp after heater core bypass

[BillNyeIsHigh]

All,

This morning on my way to work, one of the plastic pipes for the heater core broke at the firewall. I was able to bypass with a socket to get close enough to an auto parts store. Currently, the HC is still bypassed but with a 1/2" to 3/4" hose adapter.

For the life of me, I cannot get this thing up to temp to make sure the system bleeds. I did hit 190 on my drive home, however the temps were anywhere from ~165-185.


I replaced both my radiator (accidentally pierced the old one) and thermostat (drilled a bleed hole) on Friday, and I double checked that the thermostat was a 195. The jeep, temp wise, was perfect after that up until this morning.

Any ideas?

 

[BillNyeIsHigh]

It’s funny how I seem to find answers after I make a post.

I believe that my thermostat may be a fail safe stat.

If that’s the case, is it possible that it has failed open due to my overheating this morning?

 

[Jerry Bransford]

It’s funny how I seem to find answers after I make a post.

I believe that my thermostat may be a fail safe stat.

If that’s the case, is it possible that it has failed open due to my overheating this morning?

Absolutely, failsafe thermostats commonly get stuck in the open position. That's why I have long recommended against installing thermostats claiming to be "failsafe"... they're definitely not.

 

[Coadster32]

From what I have recently read and seen pictures of on this forum, depending on the heater core, the little splines called turbulators in the heater core can get pushed/pulled around the system, and lodge themselves into the thermostat. Sometimes this holds the stat open, and might not be letting you get up to temp.