Overheating temperature in a 3S-FE Options

[Titiko]

Hi guys, i get a 3S-FE in my celica, since many weeks ago i have noticed the following situation: during day by day drivin in the city the temp is Ok it achieve its operating value and it doesnt oscillate, but in weekends when i travel to a near city (about 1hrs of travel) when i have driven many miles @ average speed 90-110mph the temperature begins to oscillate, it behavior is very weird cause suddenly rise at 3/4 of the stock temp gauge and then drop to the middle of the gauge (std temp value) and it happens continuosly but each time it rises higher and higher. I dont know why it happens cause in the city the temp always is OK. I replace the old thermostat, i removed the radiator and it was cleanded with special fluid, the fans works fine, the timing is set @ 14degrees at idle, and then of checking all these things the overheating problem continues.

What do you think about this situation? what can i do? I think it coudl be the camshaft gasket, probably it get burnt.

[Hanyo]

does your car actually over heat? steam water everywhere?

I can be your radiator cap, if it cant keep the right psi in your cooling system it will make your cooling system act up, also a check your thermostat out. Just because its new doesnt mean its not broken before you installed it...

[Titiko]

does your car actually over heat? steam water everywhere?

I can be your radiator cap, if it cant keep the right psi in your cooling system it will make your cooling system act up, also a check your thermostat out. Just because its new doesnt mean its not broken before you installed it...

The coolant level is OK, I have checked it everyday since this overheating problem started..

both radiator cap and the thermostat are new, however you are right it does not mean they could be broken but with the old cap n thermostat occur the same overheating problem.

i really dont belive that the CTS could be the problem cause driven in the city the temperature always is ok.

what do u think?