1. 1 year ago, radiator cracked - replaced
2. Fine for 3 months, driving on interstate (90 degrees outside), after 4 hours ran hot and started overheating. Pulled over, add fluid. Returned 2 days later (at night when it was cooler), no problem. Replaced thermostat. Mechanic bled system
3. Ran fine for 5 months
4. 1st long interstate drive (90 degrees outside) after 1.5 hours started overheating. Pulled over added fluid. Started overheating 2 hours later. Pulled over, added fluid. Returned next day (at night when it was cooler), no problem.
5. Replaced water pump (note vehicle does not leak any fluids during all of this time, only topped off when it was overheating). Mechanic bled system
6. Fine for 1 month, same basic scenario. Changed radiator again, bled system, checked for warped head (it wasn't).
7. This time driving in city (90 degrees), started heating up when stopped, cooled down when moving. Changed both sensors, changed to OEM thermostat.
8. Still climbs from midpoint to 3/4 point when stopped (and I assuming on long hauls, I just haven't made any yet).

So changed radiator (ex), both sensors, good head gasket, no leaks, oil fine, changed thermostat (2x), changed radiator caps (2x), all hoses are good, belts are fine, changed water pump, bled several times. WHAT COULD IT BE!

 

Warped head/mating surfaces.

 

Sounds like you are losing coolant somewhere.

 

Probably being burned in the engine since it isn't leaking anywhere. The constant overheating has probably already killed that engine.

 

http://voices.yahoo.com/8-things-cau...t-7520442.html

Just a guess: Possibly a bad freeze plug with pin-hole drip. Coolant may not even leak to ground or puddle if it burns off from engine heat.

 

lol freeze plug. there isn't any.

 

Where's that confounded freeze plug?

 

And that is exactly why I said "Just a guess"

That confounded freeze plug is probably on that confounded bridge. Has anyone seen the bridge?