Heat Management, Part 8

I had a leaky radiator. Not your conventional visible leak, not a broken hose, not a cracked top casing, not anything you could see, and not the headgasket either.

Over the past two months I've been thinking, why is the water in my reservoir tank going lower and lower bit by bit? I decided to pop the hood when the engine was cold before I left my office last Thursday night and noticed that the top area of the radiator was slightly wet even before I started the engine. I kept scratching my head on what was going on. It never rained, the car was never wet.

From there, I drove back to Subang and popped the hood again, all dry. The top looked all dry. Okay.......


The next morning, I drove to work as usual as I didn't have time to take a look at the radiator. On the evening, when the engine was cold, I took a look and it was well wet again.

You sneaky bag of death. Leaking only when cold, almost, almost, causing me my life savings to satisfy my curiousity!

You can see it's wet around the plastic casing, probably a worn o-ring that's between the radiator core and the top plastic case. It was only one year old though as I remember servicing the radiator late last year!











Having the chance to re-do the cooling system, I had a lot of ideas in mind :
- Choose a brand new full aluminium radiator
- Repair the current radiator
- Get the right amount of coolant in this time with a refractrometer
- Add coolant additive
- Replace the hoses
- Check for leaks under either pressure or vacuum


I took the above ideas into consideration and went on to get a new aluminium radiator which is way thicker than the OEM one. I also do not want any chances of cracking the top case or the same leakage thingy happening again.



REPLACEMENT


So, here's the real deal :

 A Greddy replica. Good enough if you ask me after thorough inspection.

                                               Side view of the radiator. Nice and shiny.

Comparison between the old one and the new one, which is 42mm thick.

 New vs old. I will have to swap the fans over. There is also a temperature switch hole at the bottom of the new radiator.

 Double layer, it's fins were also longer in terms of length compared to the old one, this means more capacity and higher efficiency.

I forgot to take a picture of the old one, which was way smaller. It also showed presence of rust.

Adrian the mechanic working on the radiator. Taking the radiator out of the car took only a mere 5 minutes. Swapping the fans over another few minutes. Itw as a fairly simply straightforward job as the fan mount holes were all properly aligned, identical to the oem radiator.

The new radiator also came with a 1.3bar radiator cap which I think was too high. The higher the water pressure, the higher the boiling point. But you need to ensure that your cooling system is able to take that kind of pressure without bursting a water jacket or hose, or worse, the top case of your radiator if it's OEM plastic.















FLUSHING

I have decided to flush the entire cooling system. We removed the thermostat along with it's housing for water to circulate properly. I did not remove the drain plug on the block though, didn't want to risk breaking anything as it was 11pm when all this was done.

 We stuck the water hose on top and filled up the block with water. Note how dirty the water was. 5 minutes later, it was all clean. I also took the "hole cover" that came with the new radiator, punched a hole through it and covered the top thermostat housing and sprayed air through the block through the hole, hoping that most of the coolant comes out.

All hoses were then assembled, and thermostat reinstalled. I've decided not to change the hose clips as they seem to still hold tension.











VACUUM

Okay, this is the tricky part. I've also decided to vacuum the entire system hoping that as much air comes out of the system along with the coolant. The below special tool was used :



Airlift. You can view it;s functions here

 I've connected this to the top of my radiator and connected it to the shop's air compressor. It sucked and sucked and sucked and you can see all the radiator hoses collapsing. I closed off the valve and waited for two minutes to see if there was any reduction in vacuum. If there were to be, there would have been a leak.




I used a bottle of nissan coolant and pre-mixed it with a bottle of water before letting the airlift suck it all in. Once the airlift's valve was opened, it sucked the coolant right into the radiator due to vacuum being relieved. I made it a point not to pour the coolant straight into the radiator. NEVER, ever do that.

The entire system took about four 1.5litres of coolant mixture before it was all filled up. I assume the car takes about 7 litres and there was still another litre of water in there. I will explain on the said assumption later.

Done, full, filled up, started, check for external leaks again, and hopefully no airlocks. I noticed that the water wasn't bubbling even after the fan was switched on.



TESTING

 What you see on the radiator is a refractometer. THIS, is the one device that will measure the antifreezing point of your coolant mixture. This will determine if your mixture is correct or if your mixture is what you really wanted.

Only one drop is needed. I had a result of -14degrees celcius freezing point and according to the designated chart, my coolant mixture was only 30%.

I am suspecting, either I have some water left in the cooling system(upsetting the mixture) or the Nissan coolant I had was just not pure, that led to the low freezing point. Sadly, my target was -35degrees celcius.




TESTING


Night
Took the car down the highway at night to go home at full speed and temperature stayed below half. So far so good.

Day
Did the same thing on the way to work. It up to half, shit. Seeeeeeeeeems that it is running hotter than usual. There are a few possibilities for it to happen :

• Too much coolant, too little water. Although I ensure what it was less than 50/50 mixture, the amount of water was insufficient to cool the engine although I had increased capacity
• Though I had too much coolant and too little water, the coolant may not be concentrated enough or not blended properly in factory, hence the -14degrees celc reading. This means, decreased boiling point, lack of water. The coolant mixture in the radiator may have boiled. Contributed by the lack of water, it could no longer cool the engine down. Once water or coolant boils, it does not carry heat out of the engine anymore. A lose lose situation.
•  Engine oil due for service, increased oil temperature.
• I also poured in a bottle of DEI coolant additive. I wonder if it would have heated up last night itself without this in. A myvi owner reported a reduction of 10deg celc in temperature after using this.
• I did a grave mistake by not checking the freezing point of the coolant/water mixture before pouring it into the radiator. Else I would've determined if the coolant was "really a coolant".

SUMMARY

I need to organize my steps one by one, one at a time to avoid any miscalculations in data collection and analyzing. I also came to a conclusion as per below(and I will include an article stating the reasons of my conclusion later) :

• Antifreeze is antifreeze, the amount of mixture not only determines the freezing point of your mixture, but also the boiling point of the mixture. You need to balance this as once your mixture starts boiling, it just stops carrying and transferring heat. You need to keep the boiking point up, yet still having as much water as possible
• Too much coolant and little water is no use. Water is the best carrier for heat.
• Water wetters such as Redline Water Wetter and DEI Coolant additive will reduce surface tension and improve heat transfer, not at all associated with increasing boiling point. This is one good way to keep you temperatures down.

The below article is taken from http://hellafunctional.com/?p=629
Writings in bold below are either what's important or my own editings. Credits to hellafunctional.com for the detailed explanation.

Things you should know about coolant

Nov 16th, 2011

by jamal.

This will be the first winter my car will spend in a cold climate in a few years, and I realized that my cooling system is in danger of freezing if I don’t add some anti-freeze. This brought me too look up the ideal ratio of water:coolant for cold weather usage, and then lead to much more research on cooling systems and how coolant works. I thought it might be a good idea to share results on how the boiling point, freezing point, and heat transfer ability of coolant change depending on the mixture. Also, this would have been easier if my thermodynamics textbook wasn’t in a storage unit 1000 miles away.

Anyhow, because the whole point was to look up freezing points I’ll start there. The freezing point of water as we all know is 0C (32F). The freezing point of ethylene glycol, the main ingredient in most automotive coolants, is -13C (8F). That’s not very cold! The key is that when they are mixed, the freezing point gets much lower:



From that you can see that the ideal mixture for extreme cold weather is about 65% anti-freeze and 35% distilled water. Now, unless you live in Alaska or Canada or Antarctica, you might be concerned with what happens when the coolant is hot. Anti-freeze has a pretty high boiling point of 197C (387F), which is much higher than you would see in an automotive cooling system. When mixed with water, you would be right to expect the boiling point to be lower:



As you can see, it takes quite a bit of anti-freeze to get the overall boiling point of the coolant to increase by a significant amount. At that ideal mixture for cold of 65%, we’ve only increased the boiling point by about 15C (27F). That may seem like a good thing, but simply increasing the pressure of the system can more than compensate for this difference. A standard cooling system operates at about 15psi, which if filled with straight water would boil at around 121C (250F). Most engines operate at around 90-105C (190-220F), so there actually isn’t much reason to worry there. When we’re on the hot end of the temperature range, the much more important value in the cooling system is what’s called the Specific Heat Capacity. The heat capacity is basically how much heat energy the coolant can carry out of the engine and to the radiator. As far as carrying heat goes, water does a really good job. The specific heat capacity of ethylene glycol is only about 65% of water at the temperatures seen in a cooling system. That means that to cool the engine by one degree, you would need about 50% more of it than straight water. Here’s another chart for that:



From a cooling point of view, it seems ideal to have the system filled 100% with water. At that 65% mixture we’ve lost 20% of the cooling capacity of the system, and when the cooling system is being used at near capacity, such as on a race track, canyon drive, or simply a hot day with the a/c on, it could mean the difference between a fun time and blown headgaskets.
While pure water has the highest possible heat capacity, it’s not quite the ideal automotive coolant. Aside from freezing, water can also corrode the inside of engine blocks, radiators, and water pumps. We need to have something in there to keep iron blocks from rusting up and water pump bearings and seals from failing. Anti-freeze contains these necessary additives and most auto manufacturers have pretty specific requirements on the types of coolant you can use. So, for the most part it’s a good idea to put some of the recommended coolant into the system, however, if done at a lower ratio, the cooling capabilities of the car would improve. If you live in a warm climate, it’s not a bad idea to drop the coolant: water ratio down to 25 or so percent to gain cooling capacity without loosing the anti-corrosion and lubrication properties (although it will be necessary to change the coolant more often if you do this because anti-freeze degrades over time).
There are also additives on the market specifically meant for systems that run 100% water, like redline’s water wetter and motul mocool. These products also claim to improve the cooling capacity of straight water to reduce running temps. This is because there’s more to cooling than just the heat capacity of the coolant. The ability of the water to transfer heat is also important. This is where the coolant additives come it: they reduce the surface tension and “wetting” capacity of the water, which will make a slight improvement in how well heat can be transferred from the block to the water.
Most marketing and testing for these products compares a 50/50 water and ethylene glycol mix to pure water with the additive, and show dramatic reductions in coolant temperatures. Most of these gains actually come from the added water content, and not from a magical additive. However, there is still a benefit to use them because in addition to improving the heat transfer ability they have anti-corrosive and lubricating properties.
So, in conclusion, you should only use as much anti-freeze as is necessary for your climate and operating conditions, and those coolant “wetting” additives are generally a good thing to use.


You are going to have to add up to your own mixture and refer to both graphs after measuring your antifreeze freezing point on the refractometer. It is clearly stated that more water and less coolant is good whereas less water and more coolant and the mixture may not be capable of cooling the radiator down, which is what I am experiencing now.

However, I am still scratching my head on how come my freezing point is only -14deg celc. If based on the graph, the current boiling point should be 105deg celc, which is crap. However, this may change under pressure of the system being held on by the radiator cap. I've yet to find out.



Cheers

Elton