Coolant Flush - Tap/Distilled/Rain water?

Hi guys,

I am going to flush the coolant on my 72 240z which has been in there a little over 5 years now and could certainly use changing. I've got the concentrate stuff so it requires mixing with water. On my FD RX-7 I went to the trouble of using distilled water, mainly due to all the horror stories of the cooling system on those rotaries (it also has an alloy radiator), but on the 240z (which has the alloy head obviously) what kind of water do you recommend?

The car is in Melbourne - is Melbourne tap water ok? Or is it better to use distilled water - especially in a car that might be sitting for periods of time?

My parents have rain water tanks at their place also (where the car is currently stored) and I read that rain water is also acceptable to use in place of distilled water?

http://www.denso.com.au/Products/Automotive/Radiators/Technical-Information/Looking-After-Your-Radiator

Always use good quality water to blend with the coolant. Distilled water, demineralised water or rain water are the preferred options. Many town water supplies contain high concentrations of chemicals, such as salts, that are very damaging to an aluminium radiator.

However I figure someone on here would know more about this topic and be able to confirm the best way to go or at least have a strong opinion on this.

Well I went and bought 8 litres of demineralised water. $10 which is a little expensive but a small investment. I'll use rain water to flush the system.

Yeah I don't think we have heavy water here in Melbourne, so I'm sure it's fine. I just thought I'd see if anyone has any strong opinions on this or experience tearing down motors where the improper usage of water caused excessive corrosion.

I used this stuff.

http://www.hi-tecoils.com.au/?p=1118

Probably a 60/40 mix (coolant to water). I'll be topping up with water over the next couple of days if I notice the level drops.

I'm going to post a tutorial shortly on coolant flush and change. I'm sure I've done something incorrectly, but it will at least serve as a way not to do things lol...

Ok so as promised a quick guide to coolant flush on your Z. I'm going to make an effort to have more 'how to' such guides on the forum in general. Since I started a build thread on my 72 240z and I went through my previous history of owning a Z I remembered that when I started I really was very naive when it came to my Z and working on cars in general. Creating guides like this will help others who are perhaps looking to get started with the mechanical work an idea of what's involved and more confidence to give it a go.

Before you start you may want to run your car up to warm / hot and then allow it to cool again. I did a sneaky drive around the block (since it's not registered at the minute)

Step 1. Jack up your car. I like to use the cross-member to do this.

I place the axel stands under the chassis rails where the tie rods connect to. It's a solid section of the car and it won't bend the metal here.

Step 2. Remove the radiator cap.

How the coolant looks before being drained, as you can see still pretty green, not rusty water like many Z's these days

You don't have to do this (remove the cap), but it helps drain the coolant faster. You may also want to have a new radiator cap ordered in advance since a cap that looses pressure could cause over-heating. Mine seems ok, but I'll replace it later at some point - just as general maintenance.

Step 3. Drain coolant.

There is no drain 'rooster' on the 240z radiator. Unless you've gone aftermarket. Therefore we need to remove the lower radiator hose. It's held on by a jubilee clip. I recommend using a 10mm socket to undo it, but I used I screwdriver. If it's particularly old you may find it rusted in place and difficult to remove with a screw driver only. Therefore you can skip some headache and go to the socket.

Again a good maintenance item would be to replace the jubilee clips. I personally like the t-bolt/clamp's you see on modern intercooler couplers etc.. They provide a more even clamp around the hose and seem a bit more robust than older style jubilee clips which can fatigue and crack and not tighten properly.

Again not something I did as mine were still ok, but I might do that in future.

Getting the hose off the radiator pipe could be difficult as it tends to bake itself on, if it's been a while since last removed. The trick is to wiggle it left to right to try and break the seal on it. You'll want to have a bucket under the car to catch the coolant, as it will gush out coolant when it's removed.

As you can see we had a bit of a minor accident, this was pretty hard to prevent unless I had a bigger tray / bucket under the car. Hence the reason I did it in the drive as opposed to garage.

Step 4. Flush the crap out.

I used tank water (rain water) to flush all the remaining coolant out of the radiator, the heater core will still have some crap in it or remaining coolant I should say. So what I did was fill the radiator with tank water until the green stuff disappeared and all that came out was clear looking water.

You can see the clear water in the radiator pipe.

Step 5. Removing as much old coolant as possible.

The idea here is to remove as much of the old stuff a.k.a coolant (I don't recall what brand it was previously) because it could have additives in it that react with the new stuff and in some cases this could accelerate corrosion or cancel out the anti-corrosion properties of the coolant. This is why it is good to use the same type of coolant each time if possible. So make note of what you used so you can use it again in future.

In the previous step I showed how I used tank water to remove as much of the old stuff as possible. I then re-connected the lower radiator hose and tightened the jubilee clip back up and filled the radiator again with regular tank water.

Then I ran the car up to normal operating temp (about mid-way on the temp gauge.

Unfortunately not the best photo - I should have checked it when I took it, but it's about mid-way up the range. Turn the heater on and set the controls to heat to allow the coolant / water to move through the heater and back into the cooling system.

Once it's up to temp and been running a little while, turn it off again and allow the engine / coolant to cool down.

Step 6. Drain the coolant - which should be mostly water now anyway.

This should remove most of the old stuff and allow you to top up again with new stuff. The picture above is the old coolant + tank water that was drained, as you can see it looks a very pale green colour now.

Step 7. Filling with coolant again.

I didn't have a spare 'clean' funnel to use, so I cut the top off a water bottle and used that.

I filled about 3.5 litres of concentrate.

It's just a regular ethylene glycol based coolant, if you're not sure what brand to buy just make sure it's compatible with an alloy engine head.

I then used about 2.5 litres of distilled water. This is somewhat optional (see posts above), but for the small extra expense I did it, since the car will be sitting and not driven often - I'm hoping to resolve that in future though.

Step 8. New coolant, run to temp.

So with the new coolant and water mix, I started the motor again and let it run up to temp with the radiator cap off. I would squeeze the lower and top radiator hoses to try and force the air bubbles out of the cooling system and burp it. Note: Be sure to wear tight fitting clothes here, you don't want to be wearing a scarf or loose shirt and have the radiator fan grab you! That wouldn't end well.

I would top up with distilled water as I went gradually adding it if required, but honestly it didn't seem to need much only a couple of drops here and there.

Once I was confident the thermostat was open I checked to see if more water was required but didn't really need to add much. I then placed the cap back on and gave the car a few revs.

I've kept the left over coolant and water just in case I need to top up again. I guess a good drive would be useful here, then allow the car to cool before opening the radiator cap to check if the water level has declined again. Top up as necessary, but if you find you have to continue to do this often then you may have a leak - check your hoses are tightened properly or busted water pump (common) etc.. or worse blown head gasket or a leaking engine head from corrosion or overly aggressive port job etc..

I should point out that this is just the way I did it, but if you have any additional tips / tricks or suggestions on ways to do this better feel free to contribute your own thoughts to this thread.

On my FD RX-7 I used a lisle funnel.

https://www.google.com.au/search?q=lisle+funnel&

To help with the burping of the cooling system, unfortunately I didn't have it with me in Melbourne (it's in Sydney) but I recommend these as a good funnel to have and will make life easier. Although it seems the 240z cooling system isn't that hard to burp.

I'd also like to eventually switch to Evans waterless coolant - I've heard great things about it.

https://www.google.com.au/search?q=evans+waterless+coolant

But you need to ensure you are totally free of water before using this stuff and there is a transfer liquid you use. It's also expensive, but is a lifetime product. I'll probably give it a try when I have finished the rebuild on my Safari Gold motor.

I should also add that I put the old coolant in an old container, and the coolant on the drive I washed down with the tank water. Since coolant is toxic you should make sure it's not within reach of pets or small children who may try and drink it. Coolant is sweet smelling to pets in particular who may try and drink it. So make sure you keep it out of reach of children or pets.

Ideally take it to a local council chemical waste disposal place - look it up on their website.

I should also add that I put the old coolant in an old container, and the coolant on the drive I washed down with the tank water. Since coolant is toxic you should make sure it's not within reach of pets or small children who may try and drink it. Coolant is sweet smelling to pets in particular who may try and drink it. So make sure you keep it out of reach of children or pets.

 

Ideally take it to a local council chemical waste disposal place - look it up on their website.

Nice Disclaimer 

Paragraphs of how to with photos and you focus on the disclaimer lol

Paragraphs of how to with photos and you focus on the disclaimer lol

Fair point, my zoning in on the disclaimer probably has something to do with my work environment  :-\

Great how to article. What will be your next topic - timing 101 ?

Not sure on timing yet. Although the 240z felt a little flat. Think carbs could use clean + rebuild and new gaskets, maybe also fuel pump rebuild. Really need to put her on a dyno or install wideband sensors to confirm.

I will document engine rebuild and cam dial in procedure if I can figure it out.

I found this page also which has some really good info on anti-freeze mixtures / pre-cautions / recycling etc..

http://www.eetcorp.com/antifreeze/antifreeze-faq.htm

 

    Not bad Gav, back in the old days we used to take the radiator completely out . Turn radiator upside down & place a hose in bottom hose 

    fitting making sure that the hose was sealed with rag around it so as to ensure the resultant water pressure when the hose was turned on

    fully would flow thru the radiator thus removing any sediments etc would be totally flushed out via the top openings.

    There are a few other old farts on the forum who will attest to this method.

 

                                                                Regards: Alan.

           

Not sure about the "old fart" comment, but  this works. I find that a Nylex garden hose fitting is snug fit in the lower radiator hose, tighten the clamp then turn the tap on and shake. This usually results in rusty crap all over the lawn.

Thankfully when I flushed my radiator I didn't see rust deposits or other junk so I think my cooling system is in pretty good condition. Obviously if a Z has been sitting a long time and not had proper coolant used your results and methodology would be different.