Just started up myCamaro Z28 1997 for first time after rebuilt engine due to blown head gasket byoverheat (head done as well).

I noticed that thetemperature works its way up to 210 (180 thermostats), then slowly goes back to180 just after some minutes, and then slowly back to 210 and repeating over andover.

• I have bleeded coolingsystem (both places)
• Filled up with waterafter bleeding
• Replaced thermostatwith a new one (also 180)
• No smell or leaks andno mist
• No loss of water orleaks under car

Any ideas?

 

Added a movie showing temp changing

 

sounds normal fans comeing on an off should be fine ,Guages were off a bit ,hand held temp guages are cheap ,should get a close reading,some think that over 180 is boiling an it is under pressure thats normal as long as the fans are comeing on at 210 an going off at 180,no leaks should be good to go ,i went through this early one with camaros as long as your not in the red or your water light is off still good ,,blown head gasket should have had the water light come on ,wich should now be off ,your good or should be,sounds fine

 

Confirm with either a manual gauge or a handheld OBD2 scanner/reader. The stock gauges are not known to be extremely accurate, however, 210* is not bad.

Do the fans kick on the same time the temp begins to drop? If so that would explain it, but it would be a little weird because the fans shouldn't kick on that quick unless the car was tuned to do so.

 

The mark between 160 and 210 is 185. The needle came close but didn't get there, so it dropped closer to 190, not 180. What it's doing is normal, it's a misconception to think a 180 stat is going to make these engines run at 180. When sitting, temperatures will rise until the fan goes on (226 degrees), or will go down when on the open road. You also have to factor a margin of error since factory gauges aren't always dead on accurate. Wait till the heat of the summer, when the needle can hit 230 in traffic!

 

Update 1: I did put cooling system under air pressure (10-15 psi) and noticed the radiator cap leak the sealing rubber was dry. I will replace the cap and hope this is the issue. the cap should open first at 18 psi.

 

How exactly did you put it under air pressure?

And second, what do you mean by "the cap should open first at 18psi"?

 

my guess is he heated the car up is what he meens by puting it under pressure ,replace that cap your good ,or should be everyone is just letting you know what is happening is normal on these cars in there own words pretty much

 

He said he put it under air pressure. The only way I know of doing that is with a cooling system pressure kit, but to use that requires that you have the cap off since it puts the pressure in through where the cap goes. Not saying there isn't another way of doing it, I just never saw it.

 

No idea what's going on with this pressure thing... but my car (1998) idles around 185 after it's warmed up, usually will rise upwards of 200 to 190 while idling around when it's about 78 outside. When it's hotter, it'll climb over that 210 marker though, fans are almost never off when it's hot outside.