Hello everyone , I have a 03 z06 with 120k on it . Recently I noticed there was a pin hole on top of the overflow tank , which I ended up replacing . Other thing I noticed was car was running hotter then what it used to be .Sitting in garage would go up to 230F then it will go down to 220F . As soon as I start the car I can see bubbling in the coolant tank too . I took it to the dealer and they said it was blown head gasket . I asked them if they did pressure test and they said no it wouldn't do nothing since its internal leak . Not sure if really can believe them yet before I start spending $3000 that they quoted me for . Anyone had similar problems that was it trapped in cooling ?
OK before jumping to worst case scenarios there are a few things you can rule out:
1. Pull any codes out of the ECU (pending or current) - look for P0480, 481 or P1258 - first 2 are regarding cooling fans and last is overheating protection
2. Check if you are actually losing coolant or staying level
3. Rent a pressure tester, run it for a while, if you are losing pressure the system will overheat. Even a small drop in pressure can cause this. There's something called a combustion gas test that's supposed to change colour or something similar but have not tried it.
4. Visually inspect reservoir, T bracket on overflow tank, water pump, rad spout
5. Visually inspect oil for signs of coolant, visually inspect exhaust for whit(ish) smoke, pull a spark plug and check it
It could be a number of things:
1. Bad tstat
2. Clogged rad
3. Pressure drop (leak in system)
4. GASKET is bye bye
5. Coolant fan malfunction
Some are very cheap to fix others a bit more.
So try the easy bits first. Pressure testing the system is a good way to rule out a number of items.
If you even have to pull the heads off to replace the gaskets consider saving yourself a bit of cash and not doing it at a dealer. Also a great opportunity to do some untimely upgrades
See there's always a positive.