The Stovebolt Site Forums The Shop Area Engine Shop coolant level

Water expands when it gets hot, of course. So there has to be some "head space" for the expansion. Unless this truck came with an overflow tank or you installed one, filling the top reservoir to the top means some will go past the pressure cap and out the overflow tube onto the ground. Once that happens the overflow will stop. So when you look at it later to find leaks there isn't likely to be any evidence since it will have dried up when driving. Try leaving it at the level you find it when you check after fifty miles and see if you still lose coolant.

If I fill my top tank to more than my index finger can reach to the first joint it will invariably have fallen to that level next time I check it. If I leave it alone it will stay at that level. Mine has a big top tank and it takes about 2 quarts to fill it from the "index finger joint" to the top.