S2 - Gurgling and over flowing expansion tank

[Dannybowles5]

Hi everyone,

new to the forum but would appreciate some help on a little problem i think i have.

Recently dived into a S2 for the first time (well 6 months ago) not done loads of miles but this weekend after about 45-60 minutes of driving i could hear a bit of a whine so headed home. Once i was home i could hear a gurgling from the engine so popped the rear to find a bubbling expansion tank. Not little bubbles big gluging ones and the tank did eventually let some coolant out as it cooled off.

The car drove ok and never went about 87 on the temp gauge. I've started to panic thinking failed head gasket.
No milky oil, little condensation on start up but goes away after 2 mins, no white smoke when driving. No obvious oil in the water.

Got a head gasket test of amazon to check the coolant gases and run it up to temp. the liquid stayed blue all the way until the temp rose up to about 95 and it ejected the rubber bung out the expansion tank and over flowed. temp never went about 100.

Any advice on what would be a good place to start? I'm pretty sure it's a problem waiting to happen vs normal.

thanks all.

Danny

[Vsix and Vtec]

A garage.

If you have any love for the car, you'll get it seen by a competent expert.

[thegreenhell]

It sounds like the start of a head gasket failure, unfortunately. The coolant shouldn't be bubbling at that temp, so it could be being pressurised by combustion gasses passing through. You wouldn't necessarily see any mixing of oil and water, if it's just a breach between combustion chamber and waterway.

Does it burp out a glug of coolant of you rev it with the coolant cap off?

[Dannybowles5]

It doesn’t have any impact raising the compression by increasing the revs.

I’ve done an exhaust gas test and it didn’t find any evidence of gases in the coolant. I honestly thought that it was a head gasket but it didn’t show us as such.

Maybe next will be a garage visit

[Dannybowles5]

Just got it back from the garage.

after being terrified the head had blown it turned out to just be the radiator cap had stopped holding pressure so was causing the problem.

less than £20 to fix and a hours labour on the ramp working it out. very happy.