I am back...with more cooling system questions

[dgjks6]

2006 GT with 125k miles. Developed a coolant leak. Replaced the radiator, heater core, LIM (thanks to Scottydogs), hoses and elbows, thermostat and housing. Daughter took the car to school after repair. She said it ran fine. When I checked the coolant last month was a couple quarts low. She came back today and I drove the car. No coolant loss in the last month. Engine bay smells like coolant.
Every other car I have, the temp gauge goes to operating temp and stays there. The GP goes up half way, cools down to just above the quarter mark pretty quickly and the fluctuates between the 1/4 and 1/2 mark. Kind of in the middle between the two. Not very fast, but if you pay attention you can see it.

Pressure test is fine and I bought a head gasket check kit (looks for exhaust gasses in the coolant). All normal.

Do I care?

[2007GPGTSC]

Mine goes up and down when I am driving versus when I am idling unitil I manually turn on the fans. It stays @ 175ish while im moving and moves up to 190-200 when im sitting still. I think its because the radiator has no air circulation not sure tho butni just ignore it. Could be an air bubble in the system I suppose.

[Scottydoggs]

water pump could be the cause, they leak off and on at its own will, may leak today, then not again for a week or two.

the temp swing, you may have air trapped in the lim, try re bleeding the t stat housing.

these engines will run cooler when driving, sit in traffic and the temp goes up, but should hold and not over heat. then drop again when you drive the car.

[2007GPGTSC]

I do agree with Scotty. I couldnt see any leaks on my wp but could smell it and finally started to see a visible leak yesterday replaced today with the direction of scotty and all os well so far no stink or leaks

[dgjks6]

Nice to hear from you again. Thanks again for all the help.

Forgot. Also replaced the water pump (twice). I used a uview 55000 thing to fill it, it's a vacuum thing so no air is supposed to be in there. Also bled the thermostat thing (and broke once and sprayed myself with hot coolant- hence needing to replace the housing) for good measure.

How do you know the exact temp?

[Scottydoggs]

theres a pic with the temps at each line of the temp gauge out there somewhere.

when the fans come on its at 212 deg's gm engines like to run around the 210 mark. its the norm.

[Frosty]

My water pump has been seeping on and off for the last 10,000 miles. It has 170k on it so whatever its lived its life ill change it this spring.

As far as bleeding goes I kinda found a method that works for me. Assuming an empty system I take the rad cap off and the thermostat housing off. Then I dump coolant mix into either the rad or the thermostat hole until coolant fills the thermostat hole. Then I reinstall the thermostat housing and fill the radiator neck. I start it and usually it will just idle up to thermostat temp. There will be a big burp. I will top it off. Ill wait for it to burp again. Top it off. Then I put the cap on and fill the res and go for a 10 min drive. The next day (Or next time I drive it from a cold stop) I will go for a spirited drive and check the res afterwards. Usually its dropped down to half full and I leave it there. No more overheating / boiling coolant trying to get the thermostat to open up. It just works. I have done it at least 30 times on various 3800s and never had an issue other then the time that I had the fans unhooked and it boiled over while I was waiting for it to burp. Ooooops.