Coolant on Garage Floor

[FlashBilly]

My VZ Calais is loosing coolant and requires a top-up of 300-500mL after a trip of only 60-100km.
Floor of the garage is wet at the front of the car - under front bumper.
Water pump and radiator cap have been replaced twice in the last three months. (Genuine Holden radiator cap used the second time around).
At time of replacing radiator cap, the mechanic explained that the cooling system was pressurising when the motor was turned off and the (old) radiator cap was allowing the coolant into the expansion tank, causing the expansion tank to overflow, hence the coolant on the garage floor. Replacing the radiator cap initially solved the problem but only for a two-three weeks.
Two separate mechanical repairers have pressure-tested the cooling system and advise that it is all in good order.
The car has been to mechanics three times for the same issue.
Any advice or suggestions or similar experiences members can offer will be greatly appreciated. Thanks.

 

[XUV]

overflow tank not over filled?

 

[diysv6]

overflow tank not over filled?

The overflow tank operating fluid level with the triangles circles is approx. 550ml. (alloytec)

The overflow container will take a lot more when the engine vents coolant when hot, but should syphon back to the normal mark by the time the engine has cooled down.

Don't open the radiator cap when hot and cooling down, as there is a chance that the vacuum developed in the engine/radiator when cooling will be lost, and the excess coolant in the overflow tank will not be drawn back into the engine as it cools. This will leave a high level in the overflow tank. Topping up the radiator when cold will be needed, but the overflow level will be in excess of the normal levels. This could be the cause of the puddle on the garage floor. You will need to pump out the overflow, taking the overflow coolant level back to the normal triangles circles part of the dipstick.

The assumptions here are that the radiator cap valves are good, (venting and vacuum) the screw cap seals are good. The aluminium housing where the caps screws down is undamaged. The thermostat is working properly, no coolant leaks around any of the O rings etc., the heater tap is good, and all hose clamps are keeping hoses from leaking. In other words the cooling system is in tip-top condition. Overflow rubber pipe (Radiator cap to overflow tank) has no cracks, splits and is not perished as the return vacuum will be lost. If some of these other areas are faulty, then they will need to be rectified as well.

Hope this helps.

 

[FlashBilly]

Thanks for the advice....it is appreciated. The return vacuum seems to be lost - coolant is pushed out, but does not syphon back to the radiator from the overflow tank when the motor cools. Hence the need to top up the radiator when the motor is cold. Will check out the overflow rubber hose as suggested, and ensure coolant level in overflow tank is where it needs to be.

 

[99notout]

Air is easier to be sucked back in by a vacuum than coolant, that is why there is no coolant returning from the overflow tank. Somewhere there is a leak, or the new radiator cap is faulty. It does happen. One other thing, is the car on lpg?

 

[ari666]

is the car auto, and if so when was the last time it was serviced?

 

[FlashBilly]

No, not on LPG.

Yes, is an auto (5 speed). Car regularly serviced every 10,000km. Has travelled approx 3,000km since last service in November. Gearbox serviced less than 12 months ago.

 

[diysv6]

Overflow rubber pipe (Radiator cap to overflow tank) has no cracks, splits and is not perished as the return vacuum will be lost.

In passing, if the people doing the water pump replacement etc have moved some rubber hoses around, the end of the overflow rubber hose in the overflow tank may not have been pushed back totally into the overflow tank.
If the hose end is above the "normal level" (Triangles circles) overflow level, the radiator can vent when hot, but there will be no vacuum present in the hose to suck back the coolant in the overflow tank.

Also check the hose connection to the radiator cap pipe assembly, and ensure the hose has not been kinked through incorrect routing to the overflow tank.

 

[ozNick]

Had similar issue with the wife's VZ Adventra Alloytec.
Replaced stuffed radiator cap but it was still leaking - tell-tale was coolant dripping on idler pulley.
Turns out coolant was leaking from top hose connection to radiator cap housing, with the factory spring hose clamp not holding pressure. Replaced with new hose clamp from SCA.

Nick

 

[FlashBilly]

Thanks everyone for your advice. I have purchased new overflow hose...will advise on the outcome when fitted and tested!