I found this on another forum and wanted to run this by you to see if this makes sense and if you can tell me if this could also be my problem and how to test to see if this is my problem? Also, in the below passage he says "So if I run without TS, I get no overheats or spew", what does "TS" mean? And can I just bypass that so I can keep running the SUV?
And I understand the wierd overheat now:
Leaking head gasket allows compression vapor into the water jacket. Cold thermostat does not pass the vapor, (The vent in the TS is not big enough to pass all the vapor) so the block fills with vapor and pushes coolant into the (pressurized) reservoir. (So if I run without TS, I get no overheats or spew).
If there is enough coolant, it will push coolant out of the reservior, until the bubble is big enough that it starts bubbling into the bottom of the reservoir. The reservoir is connected directly to the lower radiator hose. Thermostat still closed.
Engine still warming up. Eventually, the hot vapor, or conduction, overheats the temp sender and the head overheat sensor, showing me overheat on the gauge and an alarm light. Coolant is still only warm, but spewing out reservoir, or venting vapor out reservoir.
If I turn the engine off and wait a couple minutes, the TS vent passes enough vapor to flood the jacket with coolant, and the temperature indicator instantly shows normal, and it quits spewing, although still plenty of pressure.
Finally, the TS warms up enough to open, so the bubble goes through the ts to the top of the radiator, stops spewing coolant, and the temperature remains normal.
Continued driving continues to vent vapor through the reservoir cap.
Tuesday, July 10th, 2018 AT 1:23 PM