Coolant Header Tank Pressure Issue - Water Pump Test?

[Aoki Magic Pants]

Hi everybody!

After replacing a cracked header tank, I have an issue where there is pressure coming back up the Header Tank Hose into the bottom of the Header Tank filling it, and causing it to overflow through the Header Tank Cap. Once the engine is switched off, the coolant drains completely from the Header Tank.

The engine has to run for a while before this happens & it overflows at about 1/2 way on the temperature gauge, long before the fans would kick in if I left it running.

I bled the radiator when refilling the coolant, but not a lot of air seemed to come out. Fearing the worst with a Head Gasket failure I tried 4life Coolant to see if it changed colour with the escaped gasses, it didn’t, I did a sniffer test which was also negative. The oil level is fine & nice and clean too, so no obvious signs of a Head Gasket Failure.

I replaced the Thermostat thinking it may be stuck as it’s an easy enough job, but the problem still persists.

The Heater Valve was changed to a plastic one about 7-8 years ago, the Electric Coolant Pump was changed about 2 years ago and works.

Despite the Water Pump being changed about 4-5 years ago I’m thinking that the Water Pump may be the issue and has failed.

Would I be correct in thinking that an easy test to see if the Water Pump is working would be to disconnect both pipes going into the Electric Coolant Pump, bung the “Y” pipe that connects to the Electric Coolant Pump off the Header Tank Hose, then raise the hose from the Heater Feed as high as I can and see if Coolant is pumped out of it?

The thinking being that if coolant does not come out of that pipe when the engine is turned on then that would indicate the Water Pump is not working. Does this sound right?

[steve matthews]

Check thermostat also. Reread never mind