My temp gauge this morning was running normal, but there was no heat all of a sudden the heater started blowing hot then the temp gauge went up almost to the HOT mark. then it went down to normal, couple more miles it started to climb again then it went down . then it went up then down all the way to work (78Miles) When I get to work it was normal while I was parking it shot back up almost to hot, I got out open the hood & notice that the coolant fans were not on, so I put The A/C on, and the fans came on, but the gauge didn't move. I had to go so shut car down. I had this prob. before I Changed timing belt, water pump, thermostat, all acc. belts & alt. so I had Monroe Muffler do a coolant flush..... ( he's my friend so I know he did it) I still have the same problem with coolent gauge going up & down But it never boils over if it gets to hot it make the check engine light come on then it runs like ****. O And it runs good !! no missing at all.

if it were the thermostat, the heat wouldnt be blowing very warm at all.

Sounds like the water pump is cavitating . Replace water pump. Check coolant level also. Open the bleeder valve usually located on thermostat housing to remove air from system. close valve when coolant is present while filling. close radiator cap and top off recovery bottle to correct level. These engines are prone to overheating, do not let temp gauge get in the red.

For car running hot and overheating issues, I suggest to you go through this help links. Click this link below and go through the troubleshooting procedure to take care of the problems: ----

temp gauge goes erratic? http://technoanswers.blogspot.com/2012/01/heater-blows-intermittently-and-temp.html

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Temperature gauge keeps fluctuating up and down close to red? http://technoanswers.blogspot.com/2012/01/temperature-gauge-keeps-fluctuating-up.html

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Car runs hot? http://howtobyme.blogspot.com/2011/11/car-runs-hot-in-traffic.html
-----------All types of car overheating problems and troubleshooting?

http://technoanswers.blogspot.com/2011/11/all-types-of-car-overheating-problems.html
Car freeze overnight and started overheating while driving?http://technoanswers.blogspot.com/2012/01/car-freeze-overnight-and-started.html-----------Engine Overheats and heater blowing cold?

http://howtobyme.blogspot.com/2011/11/engine-overheats-and-heater-blowing.html

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Car overheats and Air blows hot at idle?
http://howtobyme.blogspot.com/2011/11/car-overheats-and-air-blows-hot-at-idle.html
--------overheating? http://schematicsdiagram.blogspot.com/2011/12/buick-century-overheating.html
----------Car engine Overheats and transmission starts slipping?http://schematicsdiagram.blogspot.com/2011/12/car-engine-overheats-and-transmission.html
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Temperature gauge does not move and no heat when heater is ON? http://technoanswers.blogspot.com/2012/01/temperature-gauge-does-not-move-and-no.html

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This details will help.Thanks.

Sounds like you have air in the system, try burbing the system , they make a special funnail for this procedure

Air pockets will make the guage do that, and also cause your heat to come and go. Also, a poor radiator, as in rotting, or plugged up, will cause high temperature issues.

the first thing to try is turning the heater upto full heat(a/c off)if the temp guage goes down THEN CHANGE THE THERMOSTAT...(hot oil,if too hot, is thinner than the normal sae rating so the oil pressure will be lower.otherwise no real problem.

jtg

First when vehicle is cold like in the morning check and make sure that the vehicle has enough coolant/ antifreeze in radiator and reservoir. If coolant is need use a 50/50 mixture of water and antifreeze. You will need some time to do this let car run at idle until the temp guage is in the middle NOT+ normal operating temperature. At this point if the thermostat should be in the open position. Let vehicle run and check to make sure that radiator fan comes on. This should come on when guage is about midway/half way. If temperature rises above half going to h/hot and fan doesn't come on, you either have a BAD FAN BAD FAN SWITCH BAD FAN RELAY OR BLOWN FAN SWITCH FUSE. You will need to check all of the following I will help if its needed. If fan comes on and doesn't go off and vehicle continues to get hot even with fan running. Feel radiator hoses and see if the lower radiator hose is cool/cold. If it is you have thermostat that stuck closed. Replace thermostat and fix problem. If all the above is good and vehicle continues to over heat. THE BAD NEW IS THAT YOU MAY HAVE A BLOWN HEAD GASKET /CRACKED HEAD /BROKEN WATER JACKET. Basically you will need a HEAD JOB at least a head gasket. ONe tell tail sign of this is oil looking like milkshake/chocolate milk-a creamish while residue in oil or antifreeze. Contact if you need hel0p. Good Luck and thanks for using FIX YA

Let your engine warm up with the rad. cap off and see if the coolant level drops. and make sure your overflow is full. It blows cold air because there is no water getting to the heater core. And it shows a normal(ish) temp because the water needs to be touching the temp. sensor. I really do think there is air in the system and there is not enough coolant but hard to tell from here. Also as with overheating any time make sure to check your oil and look for any coolant as the head gasket seldomly holds together if the motor overheats.

your head gaskets are bad.... This is a common plroblem wiht those symptoms.