Coolant overheat system testing
Last weekend on my climb out I ended up exceeding the max coolant temp. I immediately pulled back throttle and landed. Logs showed 20s at 252F (4F over max). I fixed the issue (which was winter airflow restriction). After this I flew again and temps didn't exceed 210F.
Reviewing the manuals I am required to do a coolant system test. I attempted to do this today. Following the line maintenance manual I pressurized the system to check for pressure of the rad cap overflow. Turns out I am seeing and hearing air at the overflow tank at only 10psi. Minimum is 17.6 psi. I'll have to order a new cap and re-test as that's the requirement.
Now, my question here - is there a way I could have messed up to cause a lower pressure release? It was air and minimal fluid coming out through the hose to the overflow. I kept the pressure for several minutes and inspected all connections of the system and found no signs of leaking.
I put everything back together and did a full run-up getting the coolant temp up to about 176F. Afterwards I was not able to detect any leakage in the system and it did not appear as if there was anything going to the overflow.
