Overcooling

[Blaine B.]

What brand Thermostat?

I had an AutoZone thermostat once and the heat sucked although the temp was showing normal. Stant thermostats as well as the OEM Jeep thermostats have served me well.

 

[1990JEEPXJ]

i would think the clicking when the thermostat is opening is a bad thermostat. and once it opens, it doesnt effect the operating temp. i have a feeling you just need to flush the system really well like others have suggested. and for insurance, i would replace the temp sender. i was having low readings for a while, and when i replaced the sender, i found out i was actually overheating.

 

[higgybrain]

There is a brass stud on the valve cover. Back drivers side corner. It allows air to escape the block when you are refilling it.

 

[Blaine B.]

That's a temp sensor for the temp gauge on the dash. If it is just a stud I'd have to say the rest of it broke off, which is common with old age....but no, it is not a vent for the air to escape when you are filling the cooling system. If it was it would be spurting coolant when the motor was running.