radiator overflow tank

[Doug Waschenko]

If I fill my radiator overflow tank to the indicated cold level, the siphon immediately begins dumping fluid through the overflow hose.
It will continue to dump until there is about 1 inch left in the tank.
I have no leasks and the radiator is full. I have disassembled the entire tank and assembly and still no luck.
Do I need to replace the entire assembly or am I missing something here?

 

[rangerj]

Doug,

Without pressure greater than atmospheric pressure on top of the fluid, or pressure less than atmospheric pressure at the overflow hose, this should not happen. Where would the positive pressure, or the negative pressure (vacuum) be comming from?

Now that I have overstated the obvious, are you sure that the tank is not leaking in the area of the overflow hose? The tanks are a PVC material and tend to crack at the "welded" seams. If there is a leak it has to be in the area where the fluid stops leaking, that is about an inch up from the bottom.

This is an interesting puzzle, let us know what you find to be the cause of the problem. rangerj

 

[Doug Waschenko]

I removed the entire tank to check for just what you suggested but alas, there was no crack.
The bottle was filled with soapy water and still no leaks.
When I fill it with 'freeze, when I get to about three inches it starts to drain out of the overfill hose.
I'm stumped, this must be the twilight zone...hello Rod, is that you?

 

[betterman]

hmm that is weird, but it has to be going somewhere, either leaking or maybe your radiator wasn't as full as you think it was. Maybe have someone look underneath the car as you fill up the overflow bottle and see if they can see a drip while you are filling it.

 

[qiksho]

Hopefully your heatercore isn't leaking headbang