Hissing/gurgling from engine bay after shut off

[MisterPP]

I have a Seat Ibiza 1.8T, recently my car has been making a hissing/gurgling noise from the engine bay after shut off. I'm also losing a little coolant. I thought Head gasket straight away but there are no other signs of HG failure?!? What could cause this?

[Bennachie]

Prob HG but could be jammed thermostat (closed) or insufficient antifreeze in current climate and the rad has frozen........................

[MisterPP]

I pray it's not the HG... Could too much de-ionised water cause hissing? Since I topped it up with some a week ago.

[colin_p]

Sounds like the pressure equalising in the A/C system.

Coolant leak most likely a dodgy "flange" or a rotten radiator.

[GreenV8S]

If you have a major leak between the coolant and combustion chamber or oil ways, this leave a very obvious scum or emulsion in the coolant. A smaller leak into the chamber may not be that obvious, but can be detected easily and cheaply by using a 'block tester' to test for traces of combustion gases in the coolant. This is cheap enough to DIY, but any decent garage should be able to do this in seconds.

A small coolant loss could be caused by a weeping pressure cap, leaking joint in the cooling system, or pin hole in the radiator. You may be able to find traces of evaporated coolant around the leak. You can also do cooling system pressure test to check for leaks.

[skyrover]

Yep... The hissing/gurgling is air trapped in the system after the coolant has escaped.

In my case the radiator had a small hole in it, but as it was an old shed I chose to live with it and just top the coolant off periodically.

I used a dye that showed up under UV light to identify the leak.

Edited by skyrover on Sunday 31st December 10:25

[anonymous-user]

Check the O-ring in the coolant header tank cap!

(classic VW failure point)

[MajorCombover]

I have possibly found a small leak, small redish stain down the side of the sump, which I'm guessing is from the water pump....?

Also I will check the O ring on the Header tank just incase!

[The Rookie]

If the water pump is leaking round the shaft get it fixed ASAP, it's often a sign the bearings are going (which allows the shaft to move around and not seal properly), it can then shed the timing belt and things get pricey very quickly after that......

[MajorCombover]

The coolant leak was caused by a leaky fuel pump and radiator... All sorted now though.

However there is still that gurgling noise?!? Seems to be coming from the dipstick area. The car is not using any oil or coolant, both fluids are clean too. None of this mayo stuff. I recently replaced the dipstick.

Any ideas?

[Boosted LS1]

OP if you get any condensation or leakage in the car it could be the heater matrix?