water getting disapperared

[evox2]

i got this weird but yet headache problem. The water in the reserve tank will get less every week. i need to top up around 300ml weekly. went to mech to check, they do some sort of pressure test but don't see any leak.anyone have any idea what should i do?

 

[evox2]

by the way, my engine is m43. just check with you all, when put water into the reserve tank do i need to unscrew the overflow valve?

 

[jarance]

Do you mean the bleeder valve when you are filling to purge the air bubble?

Pressure test does not really and not always to detect leak when the leak is very minute.

Usually, the leak are located on the radiator, expansion tank and the rubber seal at the temperature sensor.

You need to dismantle the expansion ans inspect it closely for hairline crack by looking for water or brownish stain. Sometime the crack is at the bottom of tank or nozzle connection.

For M43, I think that there are some water hoses at the rear side of the engine. If the leak is there, it is quite hard to detect.
Would advise to change all the water hoses and expansion tank. It the leak persist, then it is advisable to change the radiator as well if the usage of the radiator is more than 3 years to 4 years old.

Oh yes, there is one way to check for leak. Start the engine and warm it up for about 10 minutes. When the engine is hot, turn off the engine and check for leak or water droplet at the bottom of the car. If there is water droplet, you can then trace the source of the leak.

 

[rhpw]

Although mine is an N42, it had the same thing too. After 2-3days water disappeared.
After checking, it was the 'washer' in the water tank. You need to change it.

 

[evox2]

thanks jarance for the advise.

i not sure what is the thing is called, the screw next to the radiator cap there one need to open by a philip screw driver, so filling the water to the expansion tank need to unscrew it?

 

[jarance]

thanks jarance for the advise.

i not sure what is the thing is called, the screw next to the radiator cap there one need to open by a philip screw driver, so filling the water to the expansion tank need to unscrew it?

Yup, the round screw is black in colour and about the size of 20 cents coin. It is used for bleeding the air bubble when filling with water.

 

[evox2]

Although mine is an N42, it had the same thing too. After 2-3days water disappeared.
After checking, it was the 'washer' in the water tank. You need to change it.

mind to tell me more on it, where is it located?

Yup, the round screw is black in colour and about the size of 20 cents coin. It is used for bleeding the air bubble when filling with water.

i didnt unscrew it when refilling, will it affect anything? or cause the water in the expansion tank to drop?

 

[jarance]

It is advisable to unscrew the bleeder during refilling to prevent air lock in the cooling system. Airlock will sometime cause your engine temperature to rise when the car is stuck in the jam under the hot sun.

location of bleeder.

 

[QD250]

check the hoses.... most likely the rear hose at the back of the engine...

 

[astroboy]

Agree with QD, we all can jaga the front 2 hoses going in and out of the radiator and replace them every couple of year as preventive maintenance but often we neglect the hoses at the back of the engine that goes into the firewall to feed into the cabin heater unit.

Vehicle that do not have cabin heater will fit a bypass hose there. still the hoses need to be replaced as it age through time.

 

[evox2]

i tried jarance's advise. After running hot, i checked for water mark. I found very little sip of water at the radiator top part plastic there, just wonder can i use silicon to seal it off since just the leak so minor, changing the whole radiotorfeel so wasted.

 

[jarance]

i tried jarance's advise. After running hot, i checked for water mark. I found very little sip of water at the radiator top part plastic there, just wonder can i use silicon to seal it off since just the leak so minor, changing the whole radiotorfeel so wasted.

Ahh.. my method works to detect leaks.. ha.. ha.. :rock:

No lar, dont use silicon as silicon cannot withstand pressure and heat. However some silicon can withstand heat and works well under compression but not expansion.

i have tried using Aradite Liquid metal glue but you need to have a steel band like a hose clip to hold the glue down. Sand down the area for good adhesion property. But honestly, it will only last about 6 months before the glue starts to crack due to the high temperature. :smokin:

 

[rhpw]

i tried jarance's advise. After running hot, i checked for water mark. I found very little sip of water at the radiator top part plastic there, just wonder can i use silicon to seal it off since just the leak so minor, changing the whole radiotorfeel so wasted.

Great to hear that you've solved the mysterious water disappearance.

 

[evox2]

this morning when engine is completely cold, i tried to check out the water level in the expansion tank, it just a little lower. Before start to refill, i tried to open the bleeder valve as recommended, to my surprise after i loosen the bleeder valve, the water in the expansion tank become more, just nicely the water level. Actually what happen? Previously i never loosen the bleeder valve when refilling.

 

[jarance]

this morning when engine is completely cold, i tried to check out the water level in the expansion tank, it just a little lower. Before start to refill, i tried to open the bleeder valve as recommended, to my surprise after i loosen the bleeder valve, the water in the expansion tank become more, just nicely the water level. Actually what happen? Previously i never loosen the bleeder valve when refilling.

That is because you open the bleeder valve. Water will find its own level. When the bleeder valve is open, it allow the water in the radiator tank to flow back into the expansion tank with the air replacing the water via the bleeder vent hole.

You need to fill the expansion tank and you will most probably see air bubbles coming out from the bleeder hole. After all the water is purge, you need to do another filling as follows:-

To do the job properly, you will need to start the engine and rev it up a bit and continue to fill with water until there is no longer air bubble from the bleeder valve.

Note: Please do the air purging with the bleeder slight loose but not complete remove from the hole.

This allow you to seal the hole and prevent air lock after purging the radiator of air.

 

[evox2]

That is because you open the bleeder valve. Water will find its own level. When the bleeder valve is open, it allow the water in the radiator tank to flow back into the expansion tank with the air replacing the water via the bleeder vent hole.

You need to fill the expansion tank and you will most probably see air bubbles coming out from the bleeder hole. After all the water is purge, you need to do another filling as follows:-

To do the job properly, you will need to start the engine and rev it up a bit and continue to fill with water until there is no longer air bubble from the bleeder valve.

Note: Please do the air purging with the bleeder slight loose but not complete remove from the hole.

This allow you to seal the hole and prevent air lock after purging the radiator of air.

i just did u as mentioned. but how come i didn't see air bubble coming out? just the water over flow out from there.

previously i did do bleeding, will it effect my water level during hot & cold?

thanks for your suggestion, really appreciated it...

 

[jarance]

i just did u as mentioned. but how come i didn't see air bubble coming out? just the water over flow out from there.

previously i did do bleeding, will it effect my water level during hot & cold?

thanks for your suggestion, really appreciated it...

It good that you see just water coming out cos this means that there is NO air trapped in the cooling system..

 

[evox2]

your liquid metal glue is what colour? if black then will be alright. i dont think i can use what clip to hold the glue down since the "maybe" crack is at the corner there. can i just apply the glue there and left for 2-3 days then i only drive the car again?

 

[jarance]

your liquid metal glue is what colour? if black then will be alright. i dont think i can use what clip to hold the glue down since the "maybe" crack is at the corner there. can i just apply the glue there and left for 2-3 days then i only drive the car again?

Maybe you can use this but I dont think this is good. Metal type is black in colour. It comes in 2 tubes where you have to mix in equal part. When they are mixed properly, it becomes grey. Can buy in any hardware shop. Just make sure that it is for plastic and high temperature spec.

 

[jeffreychung]

i faced the same problem too . . need to top up water weekly .