Over heating issue

Engine was overheating . . replaced thermostat and also installed new aftermarket aluminum housing to replace plastic, which seemed to temporally fix problem. Short time after, car will perform as expected and then temp gauge will spike up near red line after moderate driving time, I turn defrost on high and temp will return to normal. Turning off defrost, temp will remain normal for some period of time. Not noticing a pattern, temp will again spike. ??? 4.0 engine

Sounds like an airlock issue.

Some ideas (I assume it isn’t losing coolant, which opens up another box of possibilities.)

  1. Did you (or your mechanic) bleed the cooling system per factory procedures to eliminate air bubbles?
  2. It is possible the new themostat is defective, especially if it’s an aftermarket brand. All too often they are poorly manufactured and are defective out of the box, which is why it’s a good idea to test them before installation. But if it were failing intermittently, a pre-installation test probably wouldn’t have caught it.


Resolved . . . bleed the cooling system did the trick! Thanks!! On to the next problem . . . lol

Glad to hear it, onwards and upwards.:sunglasses: