OK, so you fill the radiator to the rim, replace the cap.
Then you start the van and drive all day, then park the car over night for the evening.
They next morning, you open the cap and oh sugar that same 2"-3" of coolant is missing again. Same as the last time I checked it a week or two ago... no more or no less,,, just about the same.
What I purport is that your vehicle has rubber radiator hoses (it's ok, mine does too)
When you get your vehicle up to operating temperature, the coolant expands and flows over to the 'expansion tank' (at least it should. The coolant expands, building pressure within the radiator until the 13-15 psi cap allows the excess to vent past to the expansion tank and stops damage to the radiator or hoses (the weakest link)
The hoses have a nylon cording inside the rubber hoses to reinforce them. Although they do not blow up like balloons, they do expand a little bit under the pressure. So are the heater core hoses expanding (if they have not been bypassed as is sometimes common in older vehicles operated in warmer climates.
Overnight, as the engine cools, the fluid contracts, and created a suction... and if / when the system is operating normally, the expansion tank refills the radiator through suction past that spring loaded 13-15 psi radiator cap. BUT it also created suction on the whole of the system, thus slightly collapsing the two large hoses slightly.
When you open the radiator cap, that suction is broken, the hoses spring back to their normal (cool, zero pressure / zero vacuum) diameter and the fluid refills them and that is where your two inches go. No more, no less.... I imagine if you had a clear window on the cap, it would be full and air bubble free right up to where you open the cap.
NOW, what you describe as coolant gushing out of the skirt of the cap??? That is not normal and I would like to see a video of that posted here. You may also post a video online on YouTuber or Flikr somewhere and put a link for us to diagnosis if you like.
Then you start the van and drive all day, then park the car over night for the evening.
They next morning, you open the cap and oh sugar that same 2"-3" of coolant is missing again. Same as the last time I checked it a week or two ago... no more or no less,,, just about the same.
What I purport is that your vehicle has rubber radiator hoses (it's ok, mine does too)
When you get your vehicle up to operating temperature, the coolant expands and flows over to the 'expansion tank' (at least it should. The coolant expands, building pressure within the radiator until the 13-15 psi cap allows the excess to vent past to the expansion tank and stops damage to the radiator or hoses (the weakest link)
The hoses have a nylon cording inside the rubber hoses to reinforce them. Although they do not blow up like balloons, they do expand a little bit under the pressure. So are the heater core hoses expanding (if they have not been bypassed as is sometimes common in older vehicles operated in warmer climates.
Overnight, as the engine cools, the fluid contracts, and created a suction... and if / when the system is operating normally, the expansion tank refills the radiator through suction past that spring loaded 13-15 psi radiator cap. BUT it also created suction on the whole of the system, thus slightly collapsing the two large hoses slightly.
When you open the radiator cap, that suction is broken, the hoses spring back to their normal (cool, zero pressure / zero vacuum) diameter and the fluid refills them and that is where your two inches go. No more, no less.... I imagine if you had a clear window on the cap, it would be full and air bubble free right up to where you open the cap.
NOW, what you describe as coolant gushing out of the skirt of the cap??? That is not normal and I would like to see a video of that posted here. You may also post a video online on YouTuber or Flikr somewhere and put a link for us to diagnosis if you like.
