Overflow tank always empty

[monterey]

Hi all,

We have had this VS V6 Exec since 97 and it has always had this weird issue that no one can seem to work out.

The coolant overflow tank mysteriously ends up empty for no apparent reason. The tank itself has no leaks and we never seem to see a puddle of coolant under the vehicle. The coolant in the radiator never drops in level, even when the overflow tank is left bone dry for weeks. The engine doesn't overheat.

However if we fill the coolant tank half way, it will disappear in a matter of 2 or 3 weeks.

Has anyone seen this before?

 

[STEALTHY™]

yes, its getting sucked into the radiator, something to do with it expanding/compressing etc, when cold or hot. you'll find if your car does overheat, it'll be full

 

[hako]

Maybe the black overflow hose which allows the overflow tank to overflow (got that?) is sucking the coolant from the tank when the car is being driven...as in a pitot tube where at the end of the tube exposed to airflow you get a lower pressure or it is syphoning the coolant out.. If this was happening you would not see it as it would only happen when the car was actually moving plus the tube dumps coolant under the wheel well where you cannot see. It would empty the tank to the level of the pickup tube in the overflow tank. Easy to check by re-routing the overflow dump hose to where it will leave evidence of this happening.

 

[hako]

I had another think about this and maybe the two black tubes which connect to the overflow tank yellow plastic tank have been swapped around. The one which goes to the radiator cap has a metal clamp on it apparently fitted to prevent this happening but maybe you tubes got mixed up during manufacture. If this were the case then your tank would never be more than half full even when hot - when cooled it would suck the half tank of coolant back into the radiator as the coolant shrunk leaving the tank almost empty.

 

[VNPOWER]

its either leaking internally or there is a hose thats come loose somewhere and its falling on the engine and evaporating. Check the Oil for a weird colour, but i highly doubt its leaking internally..

 

[walesy]

i have the same problem with my vl

 

[hako]

If the coolant was leaking it would leave a trace of dried coolant which is like talcum powder plus you would have the smell of coolant whenever this happens and "monterey" should have noticed this during the last 8 years of ownership.. I'd still bet on the tubes on the top of the overflow tank being switched as this would dump the coolant into the wheel well where it would not be noticed.

 

[sk1p]

My VS had that, but there was occaisionally a puddle of coolant on the ground, and that turned out to be a leaking water pump.

 

[markovr]

I have 2 commodores and have the problem with both of them.When it overflows it pumps water from the radiator into the overflow and it gurgles and fills the resevoir and it blows out the top down the hose and drops on the ground ...changed caps but it still does it occassionally.

 

[hold-on]

ah ha had same issiue to once.....vs 97 model have had a probelem with water pump....they seem to have a tiny leak I would suggest getting your water pump replaced.....your mechanic should put up on hoist and notice water marks/leakage