this has me a bit stumped. the water is always empty in this bottle(below the min mark) when i drive. BUT, the radiator is always full, the thermostat is working correctly, it doesnt overheat.

ive checked for obvious leaks and blockages in the bottle and its tubes. to my eye it all seems fine.

is there a likely problem thats causing this?

thanks.

The water can evaporate a bit in hot weather. Are you using water or coolent.
Might be worth checking the radiator cap as they wear out.

i'm just running water at the moment, as i flushed the radiator a month ago and havent had time to do it again.

is coolant really 'anti-freeze' more than a 'coolant'. i thought i read somewhere that coolants heat dissapating ability was actually lower than water's, but it boiled at a higher temperature and froze at a lower one. am i correct?

if my car runs at say 95C, and it never gets down to 0C where i live, would water actually be better than a coolant mix at actually cooling my engine?

cheers.

Freezing and boiling points aside ,coolant lubes the water pump and stops corrosion. Very important in alloy head engines.

cheers, more coolant it is then!

I've been having the same problem for the past few months. I have replaced the radiator cap, and have had the cooling system pressure tested which was all OK. I have the radiator filled with coolant/water in the correct ratio. My temp gauge never gets above halfway. I have to refill the overflow bottle with about 500 ml every week.

My mechanic suggested that there may be some blockages in the small tubes of the radiator that can evaporate coolant through heat dispersion. I intend buying a infrared Thermometer to check out for any cold spots during the running of the engine, instead of paying for recond or new radiator.

i just skipped the diagnosing and thinking and replaced my whole radiator. cbf. works fine now.

water loss of these small amounts are hard to find or detect with a pressure test or a quick look. If using straight water even harder as it evaporates very quickly and wont leave a green residue.

Go over all hose clamps and tighten were possible. Check under dash for heater leaks or wet floor. also water will evaporate quicker than coolant from the overflow bottle.

I also found by using teflon tape on the bleeder valve stopped a similar problem on my car.

i just skipped the diagnosing and thinking and replaced my whole radiator. cbf. works fine now.

How much did the radiator cost?

Off the top of my head, I think around $250... but don't hold me to that.

Off the top of my head, I think around $250... but don't hold me to that.

that's pretty good, did you get a reco'd one? Cause i paid $300 for a top tank, thermostat and a few hoses, and that was a pretty good price..

water loss of these small amounts are hard to find or detect with a pressure test or a quick look. If using straight water even harder as it evaporates very quickly and wont leave a green residue.

Go over all hose clamps and tighten were possible. Check under dash for heater leaks or wet floor. also water will evaporate quicker than coolant from the overflow bottle.

I also found by using teflon tape on the bleeder valve stopped a similar problem on my car.

There can be many places where leaks are possible and almost undetectable without spending a lot of time, and you need good lighting. Some you won't find unless the engine is running, and others are best searched for about 2-3 mins after shutting a hot engine down(coolant temp rises when engine is shut off so pressure rises and sometimes this is when the engine leaks).

Examples of what to look for:

water pump bearing/seal; will send out a very fine mist when engine is running, look for stains in the "throw off" area and see if you can find water "boiling off" near pump soon after shutting engine off.

small crack or cut in a hose; may not be visible unless you wriggle hoses to open up the crack. Typically cuts are from the hose clamp digging into the hose and cracks are often near where the hose pushes over the barb on metal fittings. If hose is stiff and feels hard it may be cracked and is due for replacement anyway even if not yet cracked.

rotted hose end/corroded metal fitting; usually easier to find when engine is cold, have a look/feel of every place where a hose goes onto a fitting for any sign of moisture. Look at the gap between the hose and fitting.

rusted welch plugs in the block or heads;to check the block get the car up on a hoist or ramps.

radiator holed/cracked/corroded; pull the radiator out and look for stains. If you have an auto with a cooler in the radiator that can crack/corrode and water will be going into tranny.

How quickly does the overflow bottle empty? Will it empty if you leave the radiator cap off overnight and the engine isn't run?


Freezing and boiling points aside ,coolant lubes the water pump and stops corrosion. Very important in alloy head engines.

If you don't need freeze protection then use distilled/demineralised water and radiator inhibitor. There are many brands about. Most common brands in parts stores are Castrol and Permatex. Big diesels use it too and it can be cheaper from truck places in bulk. Inhibitor does a better job of stopping corrosion and looks "off" when its no longer doing its job. Many coolants still look OK when they have turned acid.

Cheers,
Alan

Yeah I bought a new radiator for my old project (2.6 sigma) and I think it was 250 for just the radiator.

thanks heaps alan. its only ever the overflow bottle. it will go from being overfilled slightly to just below the empty mark within 100kms. it never gets any lower(in the radiator) after this though. i really dont think i'm losing it from the hoses/heater/rad/engine. the rad is always full. ive tested it over the weekend with 400kms of driving and its only the overlflow bottle thats losing the intial water.

Ok,
Some background on how a cooling system actually works first

The engine heats up, the coolant expands and then once at pressure, if any more expansion is required the coolant will be pushed into the overflow bottle. When the engine cools off again, the coolant will be brought back into the radiator as the pressure drops. Some of you may have seen cars with faulty or wrong (usually CPC) rad caps and a rad hose will suck itself in, this is becuase they have a cap that does not have a working back flow valve. You will see a little plate on the bottom which is loose, under pressure it will seal, when the pressure drops in the radiator it will allow coolant to flow back

now, the suggesiton from a mechanic above about blockages inside a radiator causing evaporation, :wtf: get a new mechanic, coolant or steam for that matter will not permiate the alloy or copper core of a radiator. The system is sealed.

Second Gen V6 have a very common issue with micro cracks in the head near the exhaut ports, the cracks are so minor that will be near impossible to detect, I have even seen them pass cold crack tests and come up good, put them on the car and the above problem, a slight amount of coolant loss over time. Try some "INOX" from a parts place, it is a grain that will not block or damage the cooling system unlike the liquid products like Chemi Weld. My KR had this issue, I used the INOX and 3 years later when I sold the car still no worries

Second issue could be the bottle itself or the hose connecting it, could be it has a pin prick in it so as the coolant is flowing both ways it is losing a small amount Have to remember the amount you are losing will not make a puddle

ALso, for the suggestion about coolant evaporating on a hot day, not so, this will not happen, my TF has not had a coolant top up since I put the motor in, the XT I have has not had a top up in over a year and the level is perfectly on the line, this is a 42 year old car (yes has a more modern cooling system)

thanks heaps alan. its only ever the overflow bottle. it will go from being overfilled slightly to just below the empty mark within 100kms. it never gets any lower(in the radiator) after this though. i really dont think i'm losing it from the hoses/heater/rad/engine. the rad is always full. ive tested it over the weekend with 400kms of driving and its only the overlflow bottle thats losing the intial water.

Why I asked about it losing fluid overnight is as Madmagna said the overflow bottle captures the expanded coolant when the engine heats up, then it gets drawn back into the engine/radiator when it cools. So if its not losing water overnight the problem is not in the overflow bottle and also most likely not in the overflow hose.

What is happening is coolant is lost from ???????. Then when you switch off and the engine cools the overflow bottle tops up what has been lost from the cooling system.

If you come in from a drive and check the overflow bottle as soon as you stop the engine you will probably see the bottle is still full (providing you haven't stopped and cooled down anywhere along the way). DON'T REMOVE THE RADIATOR CAP! Then check next morning and the coolant level in the bottle will be down, as it was pulled into the system as the coolant temp dropped.

Cheers,
Alan

Check the hoses at the back of the engine, these are often overlooked. Coolant isn't overly expensive, despite not necessarily needing antifreeze I'd still use it anyway. Remember water freezes at 0C (I know that depends on whats in it etc etc), so if you have an overnight temperature during winter of -1C, the water in the cooling system could freeze. This would be very, very bad for the cooling system - think of a beer bottle left in the freezer too long! The overflow bottle won't help because the line would also be frozen, holding back the expansion...

People often say use little coolant because it slightly reduces cooling efficient etc etc, but it really doesn't make much difference! You can run up to a 50 percent mix - and you can even by a 50 percent mix! and not notice any difference in the temperature of the gauge. Using a good anti-freeze, anti-boil, rust/corrosion inhibitor coolant is always advisable, with no less than a 25 percent mix. If using a 25 percent mix, if you ever need to top up, use premix as water will just dilute it!

Green coolant is for most cars, red coolant is only for cars that have alloy radiators and alloy heads, it uses a different mix of corrosion inhibitors. The green coolant is for any other combination and for cars with brass fittings.

Check out Tectaloy http://www.tectaloy.com

They make very good products, and are Australian owned and made.

The ready to use mixes are handy, as you don't require distilled water yourself and you can keep some in the boot 'just in case'. The premix page is here:
http://www.tectaloy.com/site/index.php?cat=complete_fill_coolants&PHPSESSID=f87a27d50c79d7d701041ab2dbf9f7a2

I'd use 'Tectaloy 90 plus', or once you have your leak sorted 'Tectaloy 100 plus'. Good stuff :)

I haven't heard of Inox for radiators, but I know their battery conditioner is really good!

Ok,
Some background on how a cooling system actually works first

The engine heats up, the coolant expands and then once at pressure, if any more expansion is required the coolant will be pushed into the overflow bottle. When the engine cools off again, the coolant will be brought back into the radiator as the pressure drops. Some of you may have seen cars with faulty or wrong (usually CPC) rad caps and a rad hose will suck itself in, this is becuase they have a cap that does not have a working back flow valve. You will see a little plate on the bottom which is loose, under pressure it will seal, when the pressure drops in the radiator it will allow coolant to flow back

now, the suggesiton from a mechanic above about blockages inside a radiator causing evaporation, :wtf: get a new mechanic, coolant or steam for that matter will not permiate the alloy or copper core of a radiator. The system is sealed.

Second Gen V6 have a very common issue with micro cracks in the head near the exhaut ports, the cracks are so minor that will be near impossible to detect, I have even seen them pass cold crack tests and come up good, put them on the car and the above problem, a slight amount of coolant loss over time. Try some "INOX" from a parts place, it is a grain that will not block or damage the cooling system unlike the liquid products like Chemi Weld. My KR had this issue, I used the INOX and 3 years later when I sold the car still no worries

Second issue could be the bottle itself or the hose connecting it, could be it has a pin prick in it so as the coolant is flowing both ways it is losing a small amount Have to remember the amount you are losing will not make a puddle

ALso, for the suggestion about coolant evaporating on a hot day, not so, this will not happen, my TF has not had a coolant top up since I put the motor in, the XT I have has not had a top up in over a year and the level is perfectly on the line, this is a 42 year old car (yes has a more modern cooling system)

Where were you last year when i needed a cap......lol you are so right.

All my overflow problems were due to a crap rad cap.

Also the motor and water, oil, is fine now just from the cap needed changing. also use the inox in other cars and is great yo get you by

Hey Alan you know too much...lol

while your here whats a good coolant brand.?

new thread im sure.
lol

Hey Alan you know too much...lol

while your here whats a good coolant brand.?

new thread im sure.
lol


I'm sure this will get some comment but I've never used coolant while residing in Aust. Have lived in some very cold places dropping to -8, but always careful how I park outside. You don't want cold wind howling through the engine bay and radiator. If in doubt I'd throw a spud bag over the engine and drop one behind the radiator.

I prefer distilled/demineralised water and inhibitor for better corrosion protection. Coolant can look OK but not be giving any corrosion protection at all, so you have to be careful to test it regularly. Inhibitor changes colour as it goes off.

What most don't realise is that coolant generally isn't there just as an anti-freeze. Its really more an anti-boil that helps car makers by allowing smaller cheaper lighter radiators, and lower bonnet lines. Then to keep the boiling point high enough for 120-125 deg running when its very hot and the car is dragging a big load up a hill, they add coolant. In race cars we have to allow for that sort of thing too, but then we run 3-4 Bar pressure to raise the boiling point. You can't run that sort of pressure in a road car so the only alternative, besides a bigger rad, is coolant at 50/50. Many forms of motorsport ban coolant(it makes tracks slippery) so I have limited experience with what product works and what doesn't.

Cheers,
Alan

I'm sure this will get some comment but I've never used coolant while residing in Aust. Have lived in some very cold places dropping to -8, but always careful how I park outside. You don't want cold wind howling through the engine bay and radiator. If in doubt I'd throw a spud bag over the engine and drop one behind the radiator.

I prefer distilled/demineralised water and inhibitor for better corrosion protection. Coolant can look OK but not be giving any corrosion protection at all, so you have to be careful to test it regularly. Inhibitor changes colour as it goes off.

What most don't realise is that coolant generally isn't there just as an anti-freeze. Its really more an anti-boil that helps car makers by allowing smaller cheaper lighter radiators, and lower bonnet lines. Then to keep the boiling point high enough for 120-125 deg running when its very hot and the car is dragging a big load up a hill, they add coolant. In race cars we have to allow for that sort of thing too, but then we run 3-4 Bar pressure to raise the boiling point. You can't run that sort of pressure in a road car so the only alternative, besides a bigger rad, is coolant at 50/50. Many forms of motorsport ban coolant(it makes tracks slippery) so I have limited experience with what product works and what doesn't.

Cheers,
Alan

That sounds good to me.

im not having a go but what do you think would be good for every day use. And yes i service my car when needed be 6 or 12mth, what inhibitor do you use. and yes race tracks and green coolant don't mix that i know! lol

Ok read a bit more

\sorry

your right

thanks Alan

That sounds good to me.

im not having a go but what do you think would be good for every day use. And yes i service my car when needed be 6 or 12mth, what inhibitor do you use. and yes race tracks and green coolant don't mix that i know! lol

I prefer Permatex inhibitor but you don't seem to see it much in Aust any more, so I've had to switch to Castrol. Cummins diesel inhibitor was good too but I always forget to buy when I'm anywhere near a place that has it.

You will need 2 tins of Castrol inhibitor(about the size of Red Bull).

1) Flush your radiator and refill with tap water and run the engine with heater on.

2) Flush again and drain rad and block.

3) Almost fill with distilled water and pour in the inhibitor. Fill rad to top and overflow bottle to mid point.

4) Run engine until thermostat starts cracking open(you'll feel heat in the top hose). If the water level drops add more water. Fit rad cap and bring up to normal temp revving the engine to get air bubbles moving and check for leaks.

5) Take car for a run down the road and again check for leaks.

6) Check water level when its cooled, and check again in a couple of days.

Before doing this its a good idea to remove the rad and give it a good clean/debug/paint. A lot of rubbish can build up in front of the rad that blocks air flow and corrodes externally. Blast the core with a garden hose from the rear. Don't use a pressure cleaner and don't do from the front otherwise you could ruin the core. Road acid and bugs weaken the exposed core(front) so be gentle with it.

While the rad is out of the way clean the air con core as well.

Cheers,
Alan

With coolant, its why I said earlier leave a couple of litres of premix in the boot, you never know when you might need it due to a cracked hose. I suggest never to refill with water (distilled or otherwise) unless you absolutely have to. With coolant, that way you are not thinning it out at all!

Tectaloy states the time period the premix coolant lasts for (you can always use concentrate and mix it yourself). Tectaloy 60 plus is 2 years, Tectaloy 90 plus is 3 years, and Tectaloy 100 plus (I'd recommend it) is 4 yrs/100,000km. You should change the coolant at that time. Changing of coolant is often overlooked, as is changing the power steering fluid, automatic transmission fluid, and brake/clutch fluid. Imagine how many cars out there have gone several years on the same auto, power steering, and brake/clutch fluid?

For info, red coolant will gradually become more widespread with the adoption of lighter alloy radiators, engine blocks etc etc. The cars that can run red coolant can also run green coolant, its just not as effective for them due to the different corrosion inhibitor. Cars spefically requiring green coolant should never use red coolant as the red coolant only protects the alloys used in engine blocks and radiators. The handy thing with the Tectaloy red coolant is that it changed colour as it deteriorates, from red to yellow! :)

At least with a good coolant you have the peace of mind and protection from boiling during hard summer work, and protection from freezing during winter.

What's the latest on this problem?
Have you fixed the issue, yet?

I recently had similar problems with the Legnum.
Each time i filled the plastic, coolant reservoir tank to "Full", after a drive, the reservoir tank would be completely empty.
For months this happened until yesterday, I found the coolant boiling in the reservoir tank after a drive.
Yesterday on the way back from Orange (about 240 kilometres from home), the needle on the temperature gauge began to slowly creep up towards the red danger zone.
By the time I got back to Sydney, my heater was not working, the car was overheating and coolant was being dumped from the reservoir tank overflow pipe and onto the road.

The cause to all this?
A crummy old radiator cap.

When the rubber seal on the cap is split or warped (see picture of mine below), it causes crazy problems with the cooling system.

So replace your radiator cap if you haven't in the last twelve months and see if the problem still exists.

http://i263.photobucket.com/albums/ii158/dimi108/P5130167.jpg

it seems better this last overflow bottle refill.

i cut about 5mm off the pickup tube in the bottle after reading aboutthe possibility of them suctioning to the bottom of the container if too long. when i measured mine, it was pushing on the bottom and wasnt angled.

as i mentioned in my other posts, the carhasnt been losing any water. it is only the amount that goes into the refill bottle that was going away, nearly immediately. i can drive for hundreds of kms and the rad level is still full, after this happens. its just been unnerving. i'll probably get a radiator cap soon too. mine seems ok, but it cant hurt to replace it.