dont ask produa ...la bro...go to the radiator specialist.. cheaper...lagi

I am not familiar with the myvi, but go take to a shop and do a pressure test. They will pressure the cooling system to 1.5 bar and see if there are any leaks.

Many leaks happen only when the car gets up to running temperature and under pressure.

If there are no leaks, you can start by changing the cheapest item, the radiator cap which would would be a few ringgit. A 9 year old car would probably have hardened hoses, and if you have not changed them, perhaps it is time you do so. A set of hoses shouldn't cost more than 100 for a set. Once you take off the hoses, you may see if the steel hose necks are not corroded...replace the neck if corroded, or in some instances if salvagable, a mechanic can slap on more RTV silicone to seal it better.
but having to refill water every ten days sounds very serious to me. The leaks should be quite easily spotted.

Water pump leaking would be rare, given if you had only run 140k, but not an impossibility. You can only spot any leaks from the water pump after you remove the accessorize drives and the timing cover.

Regardless, a normal outside mechanic would probably be better experienced to catch these sort of leaks since they would be more experienced dealing with older cars than the ones at the dealer.

Get it properly diagnosed before replacing anything.

Go to any outside workshop locally to establish whether radiator cap is faulty or water pump leaking ........ provided you found honest and trustworthy ones.
Forget about your Perodua SC! I consider their suggestion as being not honest and competent.

So far, how much water have you topped up? You may want to check your engine oil for water contamination. Can use the dipstick and engine oil filler cover to check for sludge or milky stuff. The missing coolant could be leaking into your engine.

Start your car with aircon switched off and let it warm up. Open bonnet and observe for any water dripping.

May I also suggest changing the radiator cap first, before touching the radiator hoses? Meanwhile, do check the engine oil appearance regularly.

You are losing water from water reservoir I guess that shows no or minimal pressure leak.

Since you can't find leak when the engine is running, try to look for leak on the second day before starting the car. Inspect every hose neck especially the bypass hose. The longer the car sit idle the better because you need the system stays as cold as it could.

I assume you did check the reservoir tank for leaks, right?

Well reason being to check at cold because a lot of time the coolant evaporate during hot due to very minimal leak. It is very unlikely to check for coolant stain because the coolant is already dilluted too much.

At cold the vacuum in the system will start filling up by withdrawing coolant from reservoir. It will then start to leak when the cooling system is filled.

My 10 years old myvi was having overheat issue with water in tank decrements rapidly last time. That time need to fill up water every few days to avoid possible overheating.

Sent to workshop to inspect several times, managed to find out that was a crack in the upper tank of radiator. Finally fixed the water leaking issue with replacing the new radiator upper tank.

Just sharing some tips.

My family's ol cars used to run on plain water (pipe water) without coolant, until 1 day one of the cars kept needing top ups like your scenario and could not find the cause even after replacing the cap (its usually the most common cause) and searching for leaks. I ended letting out some water in the radiator and poured in 2 bottles of cheaper (not the branded Toyota or Royal Purple) Nasa coolant just to 'dye' the water. Sure enough, a couple of days of driving around later, dried stains from the coolant at the radiator top cover showed the culprit.

If this happened, it is very serious. Coolant leaking into engine crankcase, most likely a busted cylinder head gasket. Need to take apart the engine to clean out the sludge.

And one more thing, if you need water to top up your coolant, use only distill water (pure water, air suling, Spritzer selling them in 9 liter bottle). Normal tap water contain mineral that can cause scaling in the surface of metal (mineral stuck to the metal surface), reducing their effectiveness in heat transfer in long run.

You can view it without disassembling the radiator. The leaks that I've gotten so far are between the plastic top cover and the brass/aluminium/alloy radiator body where its clamped. Leaks here happen when the plastic edge disintegrate  due to rapid temperature changes.

That rust sign on the connector looks like a good indication of a leak. If that is really the cause of it, you might also want to consider checking/replacing the radiator hoses as the long returning hose on it looked bulged at the edge of the clamp.

This is exactly a leaking point.
Clean it up, and it should help ....... and may possibly solve your problem.

FYI, The smaller hose is a bypass hose. It allows water to flow through even thermostat is closed.

The 2 rubber hoses connected by the corroded pipe is upper hose. If the corroded pipe is slightly wet to touch in the morning before starting the car then it is leaking. Upper hose should cost about rm 20, bypass hose maybe cheaper. Very easy to DIY. Can use back the corroded pipe. Just need to sand it.

Well you will have to replace both the upper hose and bypass hose. The steel pipe just work as connector for both hoses so it is extremely easy work with because myvi has plenty of space to work on compared with many other cars. It just 5 to 10 minutes work for the hose replacement.

I prefer DIY because I can thoroughly clean and replace coolant at the same time. Most workshops won't do it properly as they will mix city water with antifreeze/inhabitor. They won't take the initiative to clean the engine cooling system unless thermostat is removed. TO DIY or not it is up to you eventually.

Ya.. is at the upper part of the tank... there are some color water mark, believe is coolant... and last week mechanical found out water in tank have drop massive....

my mechnicl quote me material only rm388....(genuine myvi manual)

Ya.. is at the upper part of the tank... there are some color water mark, believe is coolant... and last week mechanical found out water in tank have drop massive....

my mechnicl quote me material only rm388....(genuine myvi manual)

ic.. yours is just part of the tank..

Are you refering to radiator cap.. ?
http://www.ebay.co.uk/itm/DAIHATSU-SIRION-...IkAAOSw~OdVXY~A 

This you can DIY, no need send to radiator/mechanic shop.