Overflowing coolant

[granto]

So my van seems to be only pushing coolant in one direction. the radiators overflow tank is basically overflowing. It this a temp sensor or the thermostat? I'd assume some form of sensor. Its like the engine thinks its cold so its moving extra fluid to the tank and of course the engine isnt actually cold. I replaced the thermostat recently so I'd assume that wasnt it, but all ideas are welcome. Thanks Grant

[Dirk]

Is it overflowing as soon as you start the engine?
If so, did you make sure that there was no air left in the system after you changed the thermostat?
In the worst case you're looking at a blown cylinder head gasket.

[chevymaher]

When the engine heats it always pushes fluid into that tank.now getting it back into the radiator a little trickier.if your system is not holding a vacuum as it cools it wont reverse direction and go back to the radiator.if the cap leaks or there a pinhole leak in the upper portions of the system it wont draw it back.It easier to draw air to stabilize pressure than draw a liquid uphill from that tank.I would check the rear heater hose at the quick disconnect fitting for a leak and the cap first.

[Phantom]

The seal on the rad cap leaking can cause this , and also the overflow hose if cracked or split will prevent the coolant from being drawn back into the radiator , you should have the cooling system checked with a pressure tester to see how well it holds pressure ,

[granto]

Sounds like it could be the vacuum issue. I found a small leak in my radiator itself so that explains the fluid not getting pulled back into the tank from your description. I'll look into replacement of that and work from there. Thanks

[tedanderson]

Change out your thermostat if it's been a while. That's about the cheapest/easiest repair and one of the few things that I'd do as a "part-changer" diagnosis.

[granto]

I was going to order a new radiator for my van now that i've figured out that there is a small leak in it causing the vacuum issue. When i called to order it though they asked me which one it was. They tried to describe the differences, but his descriptions went basically nowhere. How do i find out which one to order? Its a 93 v6 4.3l safari awd is that helps. Thanks a ton!

[Phantom]

Some have engine oil cooler on the drivers side and some do not have it , you can try using this link to see what code is shown for your van ,,just enter your VIN for the list of codes for your van build.

http://www.compnine.com/vid.php?vin=1gndm19w5xb126525

Here is a GM part selection for your year of van , the first listed one is L35 which is the 4.3L V6

RADIATOR (CORE SIZE 23 9/16 X 18 11/16 X 7/8)(CODE 3701)(TRANS OIL CLR) LM1 (L35,KPS)


RADIATOR (CORE SIZE 23 9/16 X 18 11/16 X 7/8)(CODE BY,EP,EH,EK,EL,EN,XM,XT)(TRANS OIL CLR) M1 (LB4, KPS)(EXC V08)


RADIATOR (CORE SIZE 23 9/16 X 18 11/16 X 7/8)(CODE AH,EJ,EM,EO,LT,XS,XW)(TRANS OIL CLR) LM1 (LB4, V08, KPS)