I was just checking fluid levels and found that the overflow bottle for the cooling system was completely empty.
I removed the pressure cap from the radiator and the fluid there was full but NONE in the overflow bottle.
The car is only 20 months old and has only travelled 18000km (11000 miles).
I find this very disturbing.
Any ideas?

 

Not unusual at all. Just top it up with distilled water. You'll find it won't take much to bring it to the "full" or "normal" level.

 

I find that hard to believe.
You see I also own a Mazda 323 Protoge which also has an overflow bottle (also which has markings LOW and FULL and which is used to top up the coolant level and the level drops a bit but it NEVER gets empty. It might get down to just over the FILL mark but never empty.

 

The difference between low and full is minimal. Why not top the tank up as I suggested and measure the amount you put in. Then judge whether there's need for concern. BTW, this topic has been covered on other forums and has never been shown to be a problem.

 

Ok I 'hear' what you say BUT the difference between low and full may be minimal but it is just concerning that there was not even one drop of coolant in the overflow bottle. I have never seen that before in ANY car.
Well having said that I have checked the owner manual which suggests "inspect the antifreeze protection and COOLANT LEVEL in the COOLANT RESERVOIR at least ONCE A YEAR. It then states "the coolant level SHOULD be between the F and L marks on the reservoir".
It is quite disturbing that there was NO coolant in the reservoir (and the L mark is above the bottom of the reservoir) and the car was serviced just 8 months ago when I assume that the level was ok.
There could be a leak somewhere and who knows how bad it is. Leaks don't always show on the ground beneath the car. A leak into a cylinder (head gasket) could go on undetected.
Do you understand my concerns?

 

DO NOT ADD ANY TYPE OF WATER

Only Genuine Mazda FL22 Coolant can be used. Adding any type water will dilute the antifreeze/coolant & lessen its effectiveness.

 

Thanks for the advice.
I would never add plain water distilled or not.
I wonder though about needing to add genuine Mazda FL22 coolant.
I bought a Holden (General Motors) car in 1992 and was told only use genuine Holden coolant as the core of the radiator is aluminum. It was extremely expensive but I did so for a few years and then started using an OEM brand coolant (which was advertised as being ok for my particular car) which was HEAPS cheaper. I had the car for some years after that and NEVER experienced any problems.

 

C'mon GR, get real. We're talking about adding maybe a pint or so of distilled water which, given the volume of 50/50 mix in the system, has no discernable effect on cooling or anti-freeze capabilities. You should know that, having worked in a dealership!

 

FL22 is a complete liquid. it is added as 100% content. No mixing, no dilution. NO WATER

 

If I ever have to top up the coolant in any car I never used straight water. It is always ready to use coolant or concentrated coolant mixed with WATER in the recommended ratio as per the manufacturer.
I always thought that coolant contained mostly ethylene glycol with maybe some other additives. Apart from aeroplane engines I didn't think that 100% ethylene glycol would ever be used.
Anyway the reason for this thread was to find out what could cause the coolant reserve container to be empty? I can only assume that it was checked and correct at the last service 8 months ago.
From my 'early days' I thought that a loss of coolant water caused by either an external leak (usually noticeable by coolant on the floor under the car), water pump leak or a faulty head gasket or the engine overheating and forcing water out of the pressure cap into the reservoir which then overflows and is lost.
Any of these things is a worry with a near new car (18 months old - 18000km)