ok, need a little help. My 02 Z06 started overheating on the way home from work Friday. I thought maybe the thermostat was stuck closed so at one of the stops waiting for it to cool I removed that and refilled. That didn't help. Limped home a few miles at a time. Just got done draining the system and replaced the water pump and thermostat.
Here's the problem. I don't know how much coolant remained in the system after I opened the radiator drain **** and removed the hoses to the water pump. (I did not replace hoses so there could still be coolant trapped.) When I refilled the system it took a whole gallon of coolant and then I barely got a quart of water in from the next jug before I overflowed. I went through the "burp" procedure running without the cap for a minute, then running up to 210 with cap. When I remove the overflow cap it still doesn't need water. I have been unable to add any more. I am still overheating. I assume and am hoping I have air in the lines but am not sure. I wish it had an old style radiator cap that you could leave off to see if the coolant was flowing...
Anyway, how do I know if I have a blockage or have coolant flowing? Suggestions? I hope I'm just missing something stupid and don't have a serious problem.
Also, changed oil about a month or so ago and it still looks fresh with no signs of coolant leaking in...
I read somewhere that the water pump pulley should not spin freely/easily by hand. The new one I put on does spin easily, actually felt no different than the one I removed. Could I have just replaced with a other bad water pump?
Thanks for any help.

 

How hot is it getting?
R both fans running? If so, is there much hot air coming threw?
Is the front air deflector and ductwork in good condition?
When was the last time you cleaned the debris from between the radiator and ac condenser?
How many miles are on your car?
Is it stock?

If were able to capture the coolant that cam out of the car when you did the wp, did you measure to see how much cam out? It's always a good idea, it doesn't always work - spillage. Anyway, as long as it was full before you started, and you got 1.5 gallons out and got 1.5 gallons back in, it should be not be air bound.

 

The pump should spin freely with little or no resistance. You probably replaced a perfectly good pump if it wasn't leaking. Doubt it is air as you had the same problem before you drained it.

 

It will go all the way to the max on the temp gauge and start the warning if I don't watch it. Only takes 5 minutes or so if I'm bringing the revs up and down to 3000, or a trip around the block.
There is no debris clogging the radiator.
Stock engine w/ 115K miles.
Both fans come on and run. Didn't capture the coolant as it came out to measure.
I had noticed some coolant on the floor of the garage prior to the problem. I was able to get another 2 quarts of water in after it sat for a while but it is still overheating.

 

Tried bleeding the system from the top coolant hose running from left to right head as described in this thread: https://www.corvetteforum.com/forums...erheating.html
It did take a couple minutes and then coolant started coming out around each base. However, I'm still overheating pretty quick. I'm at a loss here. I guess I can take the thermostat back off and test it to be sure I didn't get a bad one. Aaaagh!!!!

 

One other option is that you could have a weak hose that's leaking under pressure. I'm leaning towards that since you noted you've seen coolant on your garage floor before. You may want to see if a local auto supply store has a coolant system pressure test kit you can borrow. Using the kit, you put an adapter on the coolant reservoir tank instead of the radiator cap, then you hook up a small hand pump and increase pressure to 15 or 18 pounds. Keep it less than 20. Then look at all of the hose connections for anything that leaks.

 

Looking more and more like I'm going to have to have it towed so someone who knows what they are doing can figure it out. However, even if it had a small leak, that wouldn't cause it to overheat after just a few miles unless it was low on coolant would it??

 

Does your engine over heat at idle or only when you are driving the car, or both?

 

It was overheating at idle and when driving.
I think I have it resolved. I've had it out a couple times now 10-15 miles each trip and it hasn't gone over 210.
All I did since the last post was go back and bleed the top crossover tube one more time. As soon as I loosened the connection on each side coolant started flowing out. I left it open anyway for a few more minutes and let a lot run out. I assume that is what did the trick because it hasn't overheated again. It doesn't seem like the small amount of air that could have remained would make that much of a difference, but I don't know what else it could have been.
Thanks everyone for the responses.

 

I have a 2002 Z06 , and my temps in the Houston summer with AC blowing doesn't run over 196 F(192F on the highway). On a cool day with AC off, it runs around 190-192 F. Still seems like your car is running on the hot side, do you know what your temps averaged before this issue?

 

I see that was your suggestion/focus in the thread that got me out of the weeds. Thanks for that.