in my 2000 chevy venture 3.4 LS my water in my radiator pushes up instead of goes down and builds pressure on the over flow. What causes that? Would a head gasket or intake cause that?

1 Answer 1


Likely a blocked radiator or a leaking radiator cap.

When's the last time you flushed the radiator? You likely have Dex-Cool in there (is your coolant red?), this coolant is more prone to making deposits and needs to be flushed more often than GM would like to admit. I have an '04 Montana, and I had the same thing happen this time last year. Water pump was leaking, so I changed it and took the opportunity to flush the entire cooling system (I had just bought the van off a friend's old Mom). The old coolant was cruddy as heck, flushed it with plenty of water, put new coolant in there, no more boiling over since.

A new radiator cap is about $10.

  • i got it for 200 dollars so i really dk what is wrong with it unitll i was driving it's got a new water pump i put on and it still dose it
    – wayne
    Commented Oct 18, 2016 at 17:18
  • it dose it with the cap off of it
    – wayne
    Commented Oct 18, 2016 at 17:20
  • 1
    The radiator cap keeps the cooling system pressurized so that to coolant boils at a higher temperature. If your rad cap is off, collant will boil at a lower temperature and cause what you are seeing. Get a new rad cap, engine may overheat for lack of thermal contact if coolant boils.
    – tlhIngan
    Commented Oct 18, 2016 at 18:07

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