Help..... Coolant issue
 

Hi all, have a 1990 13bbpt..... never had any issues with it until i decided to enter a burnout comp.
During burnout, temp got hot...... parked it up and let it cool down, checked radiator and no water in there..... filled it back up and went out a 2nd time, same thing.
Filled back up again and noticed the overflow bottle still had water in it at the correct level, no water in radiator. When i filled up the radiator and started the car, coolant started leaking straight out the overflow hose. Radiator hoses were soft.
All the other times ive done skids in it it has always been perfect, no issues and radiator always full...

Have replaced the following:
Thermostat
Water pump
Radiator cap

Did a complete flush of radiator, filled back up and bled the system to get rid of any air bubbles.

Checked oil, no water in there and no water around the spark plugs

Took it out friday night down the 1/4 mile and on the burnout pad, same issue, coolant leaking straight out of the overflow hose, radiator didnt have to be topped up much and radiator hoses firm but water was quite dirty even thou it had been flushed and new coolant put in.... more comes out of the overflow hose after the car is turned off. Overflow bottle still has coolant in it.

Thinking i will replace the whole radiator, have just brought an aftermarket one, had to get a filler next added onto it but it seems its on a different angle compared to the standard one and may sit below thermostat height.....also factory fan shroud wont fit on new radiator so am going to have to modify that .....

Car doesnt smoke whatsoever and still runs as it should.... could it be coolant seals or does it have to blow white smoke for the seals to be blown?

Any help/advise appreciated :)

Sounds to me the engine is pressurizing the cooling system. This can result in engine pressure pushing coolant back through the overflow tank.

Well first, next time your car overheats in that situation try letting it idle so the coolant keeps circulating rather than sitting in the block and boiling from the latent heat.
Another good trick is to turn on the heater full blast. It's not very comfortable, but it does increase your cooling capacity a little when you need it most.

Did you see steam escaping? The coolant has to have gone somewhere so if it's not in the oil it either escaped as steam or wound up in another subsystem...trans maybe? White smoke is the key to detecting blown seals, but if you had it REALLY hot you might have had it escape in the invisible state.

Good luck with it!

Thanks for your comments......
Yes it seems like the engine is pressurizing and blowing the water straight out the overflow hose, not even making it into the over flow bottle...... what could cause that to start happening?
I did have the engine idling and the temp came back down and also ran water over the radiator..... after that turned it off, but could hear water bubbling.... that was before i changed radiator cap etc..... now it still comes out the overflow hose but cant hear any bubbling...... was hoping it was just a faulty radiator cap. Not sure how to upload a vid to show....
Doesnt blow any smoke which is why im really confused as everyone says it should be if it has blown coolant seals...... still boosts hard and drives like it use to...........