Basic advice on coolant please

[saracen]

Our coolant level appears to be low. Every time we have taken it in to be checked, it's always been described as low, but we did not have any problems over 15 months until the radiator completely carked out a few weeks ago. Since then it's been checked over pretty thoroughly by a good Bongo garage.
I got a low coolant alarm. Starting from cold, this beeps a bit too long for my liking, but once the engine is warm there's no alarm. I discovered Haydn's check for coolant level (cheers!) and yes, as suspected it is low when cold.
As I say, the only thing is that this Bongo seems to live on a low level (if that makes any sense). That said, it must be getting out somewhere and that can't be good. I want to top the coolant up and see how it goes, how the level drops (or not) - excuse ignorance, but what should I use? Is it just normal water? And how far should I fill it? Or should I use a coolant and if so what?
Thanks for any help you can give.

[MountainGoat]

If you know the original coolant that was used then you should top up with that, never mix coolant types. On the other hand the coolant mixture for a bongo should be 50/50 pure coolant and water, so adding water a bit too often is going to weaken the strength of the coolant which may prove to be a bad idea if we have another server winter.

Tony

[missfixit70]

As Tony said, you need to know what's in there, bit confused as to whether you've been losing & topping up over a long period, or whether its just been sat on a low level, but if you're only topping up once with a bit of water it'll do no harm, if you've been topping up before with water, it'll be diluting the strength of the the anti corrosion & anti freeze properties of the coolant. If it's sitting at a constant level in the header, albeit a bit low, you may be ok , but if you've been topping up before (with what?) then it may be a good idea to get the coolant system pressure tested to help find the leak.
If you want to top it up, best to do it when cold then fill to the max line then you know it's base level ( @ 20mm on a dipstick) That'll be a bit higher with a hot engine due to expansion (be careful if you take the header off on a hot engine).
If the level is out of the bottom of the header, then it needs bleeding to be sure there's no airlocks really, especially if it's been run like that.

[missfixit70]

Have you got a modified temperature gauge/Mason alarm fitted or anything else that can give you a decent indication of any temperature fluctuations?

[saracen]

Hi missfixit70, thanks as ever for the useful advice. I haven't put any water (or anything) in the tank as yet, so a bit of water should be okay as it stands. Basically, it was getting refills of coolant at thrice-yearly visits to the garage. I have no modified temperature gauge or Mason alarm.

[saracen]

Sorry, me again
The system was pressure-checked in August, but I'm going to take it in for another look over. I will add water - just to double check, plain water? - for now and see what it does.
Cheers!

[missfixit70]

Yup just water
Check the hoses after a run & it's up to temperature, see how pressurised they are, check the pressure cap is a 1.1bar & that it is sealing properly, see if the garage can test if it's working at the right pressure aswell.
Also make sure the rad hasn't got a vent pipe coming out under the rad pressure cap (if it does, it needs to be blocked), this one should not be able to vent, the original rad has no vent, but some cheaper replacements do, all the venting takes place at the header in the cooling system.
It should be irrelevant what pressure the cap is on the rad as it should rely on the fixed top seal to seal it completely.

[B*Witched Blingo]

You say you replaced the Radiator recently. Is the Radiator a Genuine Mazda one or is it one of those with a pipe in the top thats open (i,e needs blanking off). Some have had to seal off this extra small pipe as they were losing coolant (Equalibriant ) from it.

Not sure what the thread would be called. Perhaps a Techie could link in with this.

Not sure if this one is correct, but it may link with yours
http://www.igmaynard.co.uk/bongo/forum/ ... k+radiator
Chell