Because the radiator cap isn't holding enough pressure.
You heat up the engine, coolant pressure builds up, blow water/steam out the overflow into the reservoir, the reservoir fills up, eventually overflows WHILE you're driving, or just the water/steam kinda boils off in the reservoir, runs out on the road or just kinda steams off, evidence of the leaks goes away, you shut off the engine, coolant cools down, contracts, pulls fluid back in from the reservoir, and you're reservoir level goes down...
Take the explanation or leave it. Not saying you don't actually have a leak somewhere, but the evidence you are presenting suggests this is a likely scenario...and I'm out...
99% of the questions that are "STRANGE
" have a dirt simple answer...usually answered by a dirt simple search.
Is it just me, or does the majority overlook the obvious?
Somebody ate a whole bag of dumbass for breakfast.
Why do people continue to run a vehicle when a warning light comes on or starts flashing? Isn't that a clue that something is wrong and you probably should NOT drive it?
Is this whole car driving thing really freekin' brain surgery?
Here's something new for the crowd/clowns...
"A little bit of Google goes a long way!"
Ever notice the one post wonders for info on turbo'ing a GA16 are never heard from again after they figure out the cost???
And if you can read this, you don't need glasses! :)
And yes, I am diggin' it...