Hi guys, recently bought a 61 plate fabia 1.2 TSI 85.  I've noticed that there's a noise coming from the coolant reservoir, sounding like the coolant is spurting into the reservoir periodically, like a "puff" every now and then. The coolant circulates fine, just this noise that occurs intermittently. 

 

Is this normal?  I've never encountered this before,

 

Thanks a lot.

If all Clips & Clamps are tight and the coolant level stays constant then fine.

If you are loosing coolant then air is getting in.

 

The filler bottle is there to store the Pressurised Coolant, a reservoir.

and as the system gets hot allow expansion as required, and the level can rise in the bottle,

and as the system cools, coolant is drawn back into the Radiator and coolant system, the system breaths in effect, but does not draw in Air,

which would become Steam.  

 

So yes, noises are normal.  

The Coolant level should show constant when Cold Again, & there obviously should be no leaks out of coolant and air in.

But there are pressure caps, and an overflow.

 

Never overfill the Coolant.   Do not open the Filler Cap when Hot obviously, but then there is no need to open when cool unless putting in Coolant.

Sometimes at a Service a technician fills to MAX, the Bottle shows clearly at MAX.

and after a good hot run the Level resets to someplace below Max, but above Minimum.

(where it stays for a year until they put it to MAX again the next time.)

Hi, thank you for the reply.

 

I understand the way in which the coolant system works, and the purpose of the expansion bottle/reservoir.

 

However, these "spurting/puffing" noises are while the engine is idling.  I have only ever known coolant to trickle back into the expansion bottle while circulating normally, but the "spurting/puffing" intermittently, almost as if there is back pressure that's being released is the part that throws me.

 

Any ideas?  Does anyone elses do this?

Anyone?

I recon the answer you got is what is happening. at idle, the water circulates less and the engine gets warmer then when driving normally. Hence a car with an iffy fan  will overheat when stationary but run ok if driven gently.

 

The other reason for bubbling in the expansion bottle is usually a blowing head gasket. They either leak out, or in if gasses leak into the water, it will bubble up in the expansion bottle, perhaps with an exhaust-like odour. Water in the oil will make the inside of the oil cap look like mayonnaise and water leaking into the engine may cause moisture to come out of the exhaust, although don't confuse this with normal evaporation of condensation when warming a cold engine up!  I don't think the gasket will be gone on such a recent model though, unless you have had a leak and overheated the engine to such a degree that it has damaged the head.