Gurgle, splash!

[Covsprint]

Apologies if this has been covered several times before, but there were manymany cooling related posts, none of which seem to cover the issue precisely.

Had my Stag for coming up to a year now. Love it. Never seen the temp needle go past half way, and I use it daily.

A month or so ago, it started going through water and when taking the top off the expansion tank bottle when cold after a refill and a drive, the water level was right to the top.

The problem later manifested itself as a leaky radiator, so replaced the radiator and hoses and gave it all a good flush out. The temp remains under 90, and have been gradually topping up the water level as the air is expelled from the system. No sign of leaks.

Went to check the water today (stone cold engine), and there was a big gurgle when removing the expansion tank cap, followed by water shooting out the overflow hole in the tank.

What does this mean?

As I say, no overheating, no leaks that I can see, no water in the vee (but quite a bit of oil), no mayo on the oil filler cap and no streaks on the dipstick. Is it just something stupid like a worn cap?

Any guidance much appreciated!

[stoutgoose]

imported post

Did you notice the level in the bottle before you removed the cap?

Was there an audible 'hiss' when you released the cap, as if the bottle had been under pressure?

The 'hiss' is an almost certain indicator of early stage head-gaskett failure. However, you may have a lesser problem whereby the system is not sealing properly. Firstly, how old is the pressure relief cap and is it the correct 20psi rating? Secondly, is the expansionbottle metal neck (where the pressure cap attaches) firmly attached to the bottle? i.e. is it loose?

Both of these can cause the system to not seal properly and for coolant to collect in the expansion bottle.

Another sign of gaskett failure is a gurgling/boiling soundin the heater matrix, best heard when manoeuvring in a car park at slow speed.

Good luck.

[Stag Beetle]

imported post


What about an airlock after you flushed it and refilled?

[Covsprint]

imported post

Have ordered a new pressure cap, hose from rad to expansion bottle. Am away for a week or so, so will have a proper look when I get back.

Cheers.

[stagstr]

imported post

Hi Covsprint,

Sounds to me like you have head gasket failure. I think if any of the components weren't sealing properly, such as the metal neck to the bottle, or the rad cap, then you would not have had pressure in the bottle when you went back to it stone cold.

One useful tip I was given, in order to check head gasket failure (the sort where the exhaust gases are presssurising the cooling system, whichit sounds as if you have) is to take the car to an MOT station and ask them to take the rad plug out and put theexhaust gasesmeasuring stick - the one they shove up the exhaust for the MOT - into the top of the rad. If it picks up exhaust gases, then you have gasket failure.

Hope that helps

Ray