Cooling System

[jdw34]

2002 Vue AWD V6 93,000 miles

Hello,
I recently, two days ago, decided to drain and change my antifreeze. For the most part the job went over very smooth. I drained it and filled with water and ran for 10 minutes and let cool. I then repeated the process until the fuild ran clear. I then added the water\fluid mix. I ran the vehicle for ten minutes with the heater on to make sure everything seemed to be working okay, and the temp gauge stayed just over the 1/4 mark the entire time. Over the next day or so everything seemed okay, but this morning it acted a little funny.
It ran at the normal temp for the first part of my drive into work. Then I stopped at a light and within a couple of seconds it shot up to just under the half mark. It stayed there for sometime and I didn't hear the fan kick on. When I took off from the light it very quickly moved back down to the normal range. Again, at the next light it started to move back up, but not quite as far. I took off from the light and it started to go down. By this point I was in my parking lot and sat there for a minute to see if the fan would kick on, but after a minute or so it had not and the temp had gone back up to just below half.
Is this something to be concerned about? Did I mess something up?

Thanks,
jdw34

[1saxman]

I would say you have air in the system. Check the coolant surge tank every morning to see if it's pulling coolant into the block every time it cools off. Keep adding your 1:1 mix as needed. It should burp itself free of all air in several cycles, the exact number depending on how much air is in it. To expedite matters, you could take it to a radiator shop and let them do it all at once. I admit I'm rather in the dark as to how to handle these cars without a radiator cap. I considered doing it the old way like you, but didn't want to take any chances with Dexcool having air in the system, which is not good for an extended period, so I took both of ours in and had the dealer do it. I couldn't see how they did it but I think they went through the surge tank. The first one had a small amount of air left in it and stabilized after a few days. The second one never went down at all, so they got all the air out. In fact, he left the surge tank a little too full for that reason, but I finally took the excess coolant out after a few weeks. It's always a good idea to look at the surge tank with a hot engine every month or so and take note of the coolant level, then make sure the next morning that the level is lower, indicating a tight system that is 'breathing' the coolant properly. If the suge tank level does not change from cold to hot and vice-versa, an air leak is indicated, and this is the condition that causes corrosion in the cooling system and failure of the coolant. Dexcool is fine as long as everything is nominal.

[CaptainInsane-O]

Air in the system or the thermostat may be going south on you...