1995 Honda Accord boils over
 

My daughter owns a 1995 Accord with about 125K on it and a new timing
belt and water pump. The car was running fine for several months after
purchase when it suddenly got hot and boiled over. She had the
thermostat replaced and that wasn't the issue. Here's what I know: It
starts and runs normally, it heats up to normal operating temperature
at idle and will happily stay there all day. With the cap off, the
water level will come up and overflow the filler neck and if i
accelerate the engine, the water will pull out of the neck into the
system. Water does seem to move through the system and with the heater
on, I get heat in the cab...lots of it. With the heater off and full
cold with A/C on, temp remains the same and the cooling fans come on.
The fans will run after I shut it off. If I drive it a short distance
it is happy enough but (if the car is warmed up) after about 1/2 a
mile, the gauge will jump to the halfway point and then climb. I can
turn the heater on full bore and get it to cool some but it won't be
happy for long. If I pull over and let it idle, it returns to normal
temp.
I have bled the system according to the Service Manual for the car. I
have verified as best I can that there are no holes in the system and
I see no leaks.
When the engine warmed up, it looked like it was burping some air out,
but the bubbles were random and they were not smoky. I see no steady
stream of bubbles in the coolant as it passes through the radiator,
but when the system is closed and it gets warm the behavior is that of
an old car boiling over. There is a lot of action in the overflow tank
and it begins to fill and bubble violently.
I am out of options. I am getting conflicting symptoms as to whether
or not it is a failed head gasket and I am not sure if the cooling
fans are working while it is just running down the road since my wife
won't let me strap one of my boys to the hood while I drive it to look
and listen.
Any suggestions would be greatly appreciated.