opened the rad cap this morning, coolant shot out but rad is still filled to the top. is it possible to have too much coolant in a coolant system? and maybe that's what was burning off, excess coolant?
Some pressure in a cold system is not that unusual, but it does mean you don't have a leak.....how could it hold the pressure with a leak.
If it was cold overnight and then warmed up before you opened the rad cap it would have some pressure in it.
Cooling system uses the rad cap to hold it at 14psi(could be 12-18psi, depends on the engine model) after coolant expands with heat, when pressure gets over 14psi the large valve in the rad cap is pushed open and coolant flows to the overflow tank until pressure drops below 14psi and large valve closes.
After engine is shut off pressure goes down as coolant cools and shrinks, that's when the small valve in the rad cap opens and allows coolant to flow back in from the overflow tank.
So if it was cold overnight coolant shrinks even more, so more coolant is pulled in from the overflow tank, small valve doing it's job.
Sun comes up and engine starts getting warmer, coolant expands a bit, rad cap's large valve does it's job and holds any pressure under 14psi.
You open cap and there is some pressure.
Good news is that it's a good sign that there is no blown head gasket or leak in system.
No you can not overfill a cooling system, you could over fill the overflow tank, but all that would do is to dump some coolant out the top while you were driving.
There is no connection between cooling system and intake, exhaust or oil areas.
So no "burning off" could take place unless there was a leak in the cooling system.
There is smoke and then there is vapor, smoke will hang around vapor disappears pretty fast depending on air temp and humidity, smoke is smoke so outside of a good breeze it will hang around.
Smoke coming out the exhaust pipe on acceleration after idling for 30 sec to a few minutes, could be a sign that your intake valve guide seals are wearing out, not a major issue until you are consuming alot of oil between changes or fail emission test because of it.
The valve guide seals are rubber boots in the valve cover area, they are on the top end of the valve stems, they prevent oil and oil vapor from being pulled into the intake manifold, they can get brittle as they age.
At idle the intake manifold has it's highest vacuum so that is when the most oil would be pulled in through leaking seals, when you accelerate this oil is pulled off the valve all at once and burned which produces the blueish smoke.
Vapor smoke is normal depending on temp and humidity.
All gas engines produce water in their exhaust, gas(H) and air(O) when combined and burned produces some H2O(water), this is why exhaust systems rust from the inside out.
If air is humid then engine is sucking in even more water vapor along with the air it needs to run.
All gasoline will have some water in it as well, so depending on % you may notice more vapor from one fill up to the next.
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