Coolant Overheated what other potential issues to check?

TLDR:

Boiled over at 130c once.
overheated at 100c twice.
Overflow tank was at 70% then was close to overflowing at 90%.
Then after boiling over replaced with fresh coolant and water mix, at 50%, overflow tank went up to 90% then back down to 50% after a rest.

Suspected faulty intermittent thermostat.

BUT what other damage should I look into since I boiled over once.
Engine still runs fine and no other odd or different sounds or vibrations??

Context: (sorry it’s long)
I went out on the trails picked up a small 2,000lbs wet trailer.
Left the house with oil at full and coolant overflow tank at around 70%.
Drove about 200km (3hrs) to make a pit stop and saw that the overflow tank is overfilled.

Thought nothing of it and thought it will all go thru the rad in a moment.

After an hour of driving off-road all was well until I saw the coolant temp spike up to 100c then pinned to 130c then noticed the HVAC set at cool blow hot air.
Pulled over ASAP and saw the overflow tank boiling over. Turned the engine off and waited to cool.
After a hour of waiting the overflow tank was empty but no leaks anywhere, and no white sweet smoke from the exhaust.

Filled up with coolant, and drinking water mix as per instructions. Burped the system, and set off.
15min later temp spiked at 100c stoped. And waited again.
40min later we drove another 30mins before making camp for the night, she spiked at 120c.
Inspected the coolant and empty again. Filled up the radiator the next day, and burped the system filled overflow tank to 50%.

Drove back into home 200km fine and no issues at ALM.
Then decided to spiked at 100c after a 15min drive to get gas no trailer. Overflow tank again at 90% full.
Got home and overflow tank back to 50%. I suspect it’s an intermittent thermostat.

but I want to know since I boiled over once what other damage should I look into?

 

The coolant reservoir will fluctuate as the coolant heats and cools.
I’d keep an eye on the actual level of the radiator. If it stays full, I’d say you are ok.

As for overheating it, you could potentially cause the heads to warp or blow a head gasket.
But let’s not get ahead of ourselves.

Just keep an eye on the coolant level in the radiator.

 

Yes I agree coolant expands and contracts. but I think this is excessive and this is when I stopped when the coolant temp was at 100c. That is when I filled the radiator to full and left the coolant res at 50% (as in between the sign “fill” and “full”.

 

That does seem excessive.