New to forum. Thanks in advance for any answers.
New to me..2004 convertible. Has cooling issues.
Replaced ALL hoses and belts, new radiator, new water pump, new thermostat and housing for same, drivers side cooling fan replaced.. both fans checked for proper operation. Still runs hot.
Driving down hwy..65mph + temps..220-230... not bad... stop and go traffic.. easily gets up to 240-249...Pull over and park for 5 min.. does not seem to cool down. turning off A/C does reduce temp by 2-5 deg. reducing speed to... 40 mph.. temp may go down to 239 or so.. but never get back in the normal range of 220-225
Latest is BOTH gauges.. the round one and computer.. failed to read coolant temp... round gauge went max and stopped.. computer gauge reads..x x x deg F..no readings for over 30 minutes.. tried shut down and start..no difference.. Next day.. started up and both gauges are reading coolant temps.
Plan is to replace sending unit on coolant temp... and ????? What else is left to do?? Thought is that it has been running "ok" all along.. but sending unit is sending false readings and fails on occasion.
Any idea's? all service done at Chevy dealer..

 

No leaks in surge tank.. no loss of fluid.. and NO, do not see any boiling ... my hope now is the sending unit has been sending false info to gauges.. and replacing that will get temps to READ accurately.. Will post after that repair .. results

 

Next Day... just replaced the coolant sending unit.. just in case I was getting bad info.. STILL overheats.. I don't know of one single additional cooling system part that has not been replaced.
Today..5,500' elevation.. 95 deg.. around town.. 226-232 Not bad..Climbing local mountain at 35 mph.. NOT getting on the engine at all.. it reached 260.. Warning horn sounded.. computer gave warning..
turned around and went downhill.. cooled off rapidly to 232 deg.
ANY idea's?? have replaced radiator, all hoses, thermostat and housing, repaired drivers side cooling fan.. operation of both fans OK, water pump. Now temp sending unit..
I am running out of idea's.
I have ordered a kit from Sacramento Corvette.. that will allow me to remotely turn on both cooling fans on high at the flip of a switch..
My hope is this will cool things off when climbing hills or in stop and go traffic. ANY thoughts appreciated.

 

Maybe I missed it but did you blow out the condenser? Also did you disconnect the coolant line under the throttle body to ensure antifreeze was coming out? Did you try the burp procedure? Take a laser thermal gun and check the temp into the radiator and then back to the engine.

 

Make sure the top of the AC condenser is clean and make sure it is sealed to the radiator shroud. The foam between the condenser and the shroud tends to blow outwards into the engine compartment so air can bypass both the condenser and the radiator. Also make sure the radiator fans are operating correctly. Just because both are running doesn't mean they are both running in high speed operation. There are two relays involved and they are switched so change the fan motors from running in series with each other (slow speed) and in parallel (high speed). If one of the relays goes bad or the wiring isn't correct or making proper connection you can go from two fans running on slow speed to just one fan running at high speed. Make sure both fans are running on high speed when the temp is above 240 and the car is sitting still. The fans are turned off after speed reaches 35 mph.

Bill

 

Do the burp first. I jacked up the right front corner of the car, that raises the tank a little so that helps. Follow the steps to the letter and report back.

 

Just did mine (burp) last weekend. My 2000 has always been an easy burp.....but it does take a few heat up cycles.

 

Sounds like I need to try the burp.. on my 04.. done everything else..
Will post my results

 

If you need some "how to" instructions, P.M. me....I'm happy to help you.