Coolant Change - Winter's approaching...

[RaddCruisers]

I just thought I'd chime in on the subject of coolant changes for a moment since it's that time of the year again.

Virtually every JDM I have seen (and many local vehicles too) are running old and under-performing coolant.

A few things need to be noted:

- Please capture and recycle your coolant.

- Replace your coolant every 2 years.

- Long life coolant that lasts for zillions of kms is a fairy tale. Do not for a moment believe that it's going to last for 5 years and 250,000 Kms (just read about GM's problems with OAT coolant technology and DexCool if you don't believe me).

Coolant does many things, but the three main ones are:

1. Corrosion protection. This does not really start until you hit the -36C mark. If you have less than -36C you're going to be making an electrolyte solution out of your coolant. This will cause the various metals in your cooling system to dissolve and plug the system as they precipitate out of solution. Frost plugs will corrode through, head and other gaskets will be eaten up etc... etc... (this is bad, and it's expensive - much more than the cost of coolant changes every two years).

2. Freeze protection. This is obvious.

3. Lubrication for your water pump.

Running water or a weak solution of coolant is very, very bad for your engine and cooling system. Unless you like spending gobs of money on repairs, do not do this.

You should not have less than a 50/50 mix of coolant and distilled water in your system. This does not mean that you simply fill it with 50/50 and you're good. The final test must be 50/50 at a minimum. With a hydrometer, this means you will have -36C or better. Aim for about -45C.

Change your upper and lower rad hoses, and if you have no record of your thermostat being done then you need to do that too. The thermostat is a special one, it has a valve at the bottom that closes against the water neck assembly/water pump. The factory ones are the best quality, but there are others out there that work properly. If you don't have the little valve thingy on your thermostat, you may not get much heat in the car.

Once you have flushed your system, start with adding straight 100% coolant - Universal green is fine.

When you have two jugs in (about 3.8L x 2) then you can top up with distilled water or a 50/50 mix. The system may hold a lot of residual water if you do not pull the block drain plug, and even so there will be lots of water in there.

Install a new rad cap 0.9 Bar (13PSI) when you do a coolant change (Napa part 31333)

Clean out the overflow container, and make sure you top it up to the proper mark with 50/50 mix.

Test run your system and bleed out any air pockets. Have your heat control set to hot, and if you have any rear heaters, set those to hot as well. You should have hot air coming out your heater when you have things bled correctly.


Hope this helps, and if you have any questions, stop in and see your local Delica mechanic.



Cheers,

John

E4 Auto Repair Ltd.
Radd Cruisers 4WD
Duncan, BC

[mararmeisto]

Good post, and timely too, even for the Island.

[Deli of the North]

Hi John- A quick question- You mentioned that corrosion protection doesn't really start until -36? Does this mean the temp rating of your solution in the motor- as in it is corrosive IF the water/coolant mix is "mixed" to be rated past 36 below? Please clarify!! Thanks, Kevin

[RaddCruisers]

Whether a solution is corrosive, or not, is a factor of pH. Coolant does change in pH over time, and that is one reason to replace it.

Corrosion of metal is more a property of the electronegativity of the various metals that make up the engine and which are contained in the cooling system. In a perfect situation where there are no ions in solution, corrosion will not take place. In the real world, there are lots of ions in solution, both in the water that is added to the cooling system (since most of us do not use de-ionized distilled water) and as a result of the ongoing dissolution of metals found in the cooling system. These ions create an electrolyte solution that has the ability to conduct electricity.

The conduction of electricity by the cooling system, that goes unchecked can lead to rapid degradation of the block metal, frost plugs, radiators and heater cores. Much of the conduction found in cooling systems is caused by poor or improper grounding of electrical connections and added accessories. Also, when work is performed on a vehicle, all of the electrical connections and grounds need to be properly hooked up and maintained (cleaned, rust preventative used where appropriate) top reduce the potential for electrolytic damage.

You can check for electrical conductivity in your cooling system using a digital multimeter - there are articles on this subject on the internet. The basics of this are to place the setting to 5 V DC (or a low voltage reading), put the black probe on the negative battery terminal and the red probe into the radiator neck (don't touch the metal sides) and into the coolant. After two minutes or so, you want to see a reading of no higher than 0.3V. Test this with the engine on and off, and with your normal accessories on and off.

Coolant has chemical additives that are in place to control corrosion of the cooling system metals. Preventing the "rusting" of the metals is a function of pH and the concentration of the additives in the coolant. If the additives are too dilute, you are not going to get the protection you need. This is the main reason why I note the need for a minimum of a 50/50 coolant and distilled water mixture - the additive package is too weak to perform its job it there's not enough of it in there.

The water you add to your cooling system plays several roles, the primary one is to dilute the coolant to the proper concentration which allows it to work properly.

Water that comes from our taps contains all kinds of minerals (more or less depending on where you live) that can lead to scale formation - deposits of minerals in the cooling system (people who live in an area where hard water is common will know all about scale). These deposits do not conduct heat well (they are an insulator) and they also block coolant passages.

Tap water often contains compounds of chlorine as a disinfectant. These compounds can promote corrosion in the cooling system as well - and is another good reason to use de-ionized/distilled water in your cooling system.

In a nutshell: test your coolant using a hydrometer and a voltmeter. The hydrometer should read -36C or better and the voltmeter should read 0.3V or less.

If you replace your coolant every two years, you will be in a good position to prevent cooling system corrosion and plugged cooling system passages.

hth, and ymmv.

John

PS it seems take about 1.5 jugs of coolant (3.78 litre jugs) to hit the right mark in a Delica

Hi John- A quick question- You mentioned that corrosion protection doesn't really start until -36? Does this mean the temp rating of your solution in the motor- as in it is corrosive IF the water/coolant mix is "mixed" to be rated past 36 below? Please clarify!! Thanks, Kevin

[Erebus]

Water that comes from our taps contains all kinds of minerals

Since getting distilled or deionized water is a pain, how about water run through a Brita filter? Is there any point? Or is it a useful compromise?