Overheating problem

[DavidPdF]

The other day I got the low coolant warning light and topped off my coolant.

After a few days my car overheated slightly (one mark over 12:00). When I stopped I noticed steam. When the car cooled off I added coolant and started to drive. Again I went on mark over 12:00 but when I turned on the heater at full blast it went back to 12:00.

When i got home the coolant tank was cracked. I replaced it and .... same problem.

Next step, replace the CTS and ... same problem.

Seems strange because the heater can keep the temp around 12:00.

Gets worse on the highway and better around town.

Any ideas here I should look next.

[BITURBOB5]

Have you done waterpump?

[sherbet]

also, make sure the hoses are all good, not cracked. The thermo. could be sticky, or the water pump could be shitty. The coolant temp needle should generally be right in the middle, dead center.

[KNaudi]

Check that this fan is coming on with the A/C

[sqitis]

Sounds like stuck thermostat.

[DavidPdF]

Timing belt was done at 80K before I had the car, don't know if waterpump and thermostat were changed. It is now at 100K