Radiator flushing & Stray Current testing procedures.

Submitted: Saturday, Jan 17, 2004 at 23:07
ThreadID: 9828 Views:15212 Replies:8 FollowUps:8
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Cooling System Flushing Procedure.

Because coolant/inhibitors from different manufactures have different chemical compounds, which may adversely react if mixed, it is important that you DO NOT create a chemical cocktail within your cooling system by mixing different brands of coolant/inhibitor. Even though the coolant has been drained from the system, the inhibitors remain affixed to the cooling system components and must be chemically removed, using a quality alkaline flush.

1: Ensure the cooling system is sound and free from leaks and check all components for wear and condition. If need, replace worn components.
2: Choose a quality alkaline cooling system flush (500mL. Per 12 Litres). Observe the instructions on the container.
3: Replace the radiator cap and run the engine at operating temperature for 15 minutes in 4 cylinder vehicles and 30 minutes in 6 or 8 cylinder vehicles. (Ensure the vehicle heater is turned on).
4: Drain and rinse the cooling system including the overflow bottle and heater core. At this point a power flushing machine may be used if this equipment is available.

4a). Rinse the system with clean water until you are convinced that the only fluid remaining in the system is clean water- RINSE- RINSE- RINSE (this may need to be refilled and drained a number of times).
5: Refill the cooling system using clean water (demineralised or distilled water), to perform a stray current check.
6: Do not add coolant at this time until a complete stray current check has been performed (refer to stray current procedure). The presence of stray current will deteriorate the cooling fluid quality immediately.
Always ensure you select a coolant/inhibitor that meets the vehicle manufacturers recommendation or one that meets AS 2108-97 Type A or Type B whichever is recommended as being in support of the vehicles manufacturers recommended coolant performance standard.
7: Ensure the correct rates of coolant/inhibitor is used, as overdosing or underdosing will have a direct affect on the performance of the cooling system and the life of the components including the radiator.
8: Only after the vehicle has been cleared of the possibility of stray current (electrolysis). Rebuild the cooling fluids by first adding the selected product then topping up with clean water (demineralised or distilled water). NOTE: NEVER MIX TWO BRANDS OF COOLANT!
9: Mix a portion of the coolant for the owner to use for topping up coolant level.

Dispose of Waste Fluid Correctly.

Radiator manufacturers warranty does not cover internal or external corrosion.
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Reply By: awill4x4 - Saturday, Jan 17, 2004 at 23:11

Saturday, Jan 17, 2004 at 23:11
Stray Current Testing Procedure.

Diagnosing Electrolysis/Stray Current Corrosion Testing procedure.

(Please Note:)
It is recommended that a qualified Auto electrician or Radiator Repair Specialist carry out this procedure.

Tools/Equipment Required.
Voltmeter (multimeter) with a scale able to read in millivolts (Analogue voltmeter is preferred).
A radiator industry designed stray current detector preset to 50mV. (0.05 volts)
Target range below 50mV. However any voltage reading in the cooling system should be corrected, as further deterioration will cause major damage.

1: Connect the voltmeter or current detector negative terminal to the battery ground and the positive terminal directly into the coolant (ensure not to touch the metal core or filler neck).
2: With the ignition on and again with the engine running, check EVERY component. Whilst you are monitoring the presence of stray voltage in the cooling system, have a fellow worker operate the brake lights, parking, head and high beam lights and indeed all electrical components (whether factory or aftermarket) and check for any increase in voltage readings in your voltmeter.
If you get a reading above 50mV (0.05 volts) or a red fail light on the current detector.
Do Not Proceed:
The source of the current leakage should be found, as this can destroy a radiator in a short period of time (hours or days, depending on the level of voltage) and severely damage other engine components.
It is highly recommended that all repairs or work carried out on a vehicles electrical system or component is carried out by a qualified auto electrician.
The cooling system cannot be successfully passed as being free from stray current voltage if the system contains coolant, it has been found that coolant may provide inaccurate readings.
Only when the analogue voltmeter reads below 50mV (0.05 volts) or a green pass light is obtained should you proceed to fit a new radiator or recharge a cooling system with coolant.
In both cases the flushing procedure should be followed prior to the vehicle being released.
Some coolants have been known to retain an electrical charge after the fault has been detected and repaired. All testing for stray current should be carried out using clean water (demineralised or distilled) after the flushing procedure has been carried out. It would be very wise to test the vehicle again in one or two days to ensure stray current related problems are corrected and coolant has settled down.

AnswerID: 43393

Reply By: MartyB - Saturday, Jan 17, 2004 at 23:45

Saturday, Jan 17, 2004 at 23:45
Could you explain where all this info came from.
Is it from a reputable source or is it something you wrote yourself?

from Marty.
AnswerID: 43397

Follow Up By: awill4x4 - Sunday, Jan 18, 2004 at 14:57

Sunday, Jan 18, 2004 at 14:57
Marty, all this info came from a booklet named "Radiator Failure" written in conjunction with Denso (the largest manufacturer of original equipment alloy radiators) and either the VACC or its NSW equivalent.
I know that some posters here are sceptical but it is a very real problem and some simple procedures in flushing and stray current testing WILL prolong the life of your alloy and brass/copper radiators.
I have seen the results of stray current on a custom alloy radiator where the owner installed a massive sound system, didn't check for stray current and it killed the radiator in less than 3 weeks. Now this radiator cost the owner between $900 - $1000.
Whenever I buy an alloy core I always get a disclaimer from the manufacturers stating the correct procedure for flushing/stray current testing and the fact if the stray current is present above .05V the radiator is not covered under warranty.
If the radiator manufacturers are concerned then I think that is good enough for me.
Any other who don't believe the problems should check out the "ARE" (Aluminium Radiator Engineering) website. These guys are the best of the best in quality (my welding is probably their equal, but they go all out with polishing etc). Go to are.com.au and then check out the horror photo's which I think are in the tech section, then come back here and say that "stray current" and "mixing coolants" is bulltish.
Regards Andrew.
FollowupID: 305726

Follow Up By: howesy - Sunday, Jan 18, 2004 at 18:42

Sunday, Jan 18, 2004 at 18:42
Look up electolytic corosion and read up on all of it's aspects. Similarly dissimilar metals when put together can also result in eventual failure such as aluminium and iron. when putting aluminium on to bare steel it is always advisable to use an insulating coating such as zinc. Read up on the whole subject it makes some interesting food for thought.
FollowupID: 305739

Reply By: V8troopie - Sunday, Jan 18, 2004 at 00:59

Sunday, Jan 18, 2004 at 00:59
Stray currents in the coolant ??? Now I've heard everything. Well, perhaps if someone was foolish enough to refill the radiator with salt water :-)

What exactly is in coolant? Just out of curiosity I got the container of coolant I bought the other day from the garage just now. Its 'clean team' RCI-60, ready to use, complete fill. Just reading the label:
It says it contains the latest long life carboxylate rust inhibitors and glycol, 60g/l.
I guess a large proportion is water, some green dye, anything else?

It does say its incompatible to mix with other brands. I never do that anyway but I wonder if this is mentioned, perhaps, to entice the buyer to keep buying a paricular brand?

It does say to completely flush out the system before refilling, makes sense too.

There is no mention at all about stray current measurements. One would think if that was so important the coolant makers would include this on their labels??

AnswerID: 43398

Follow Up By: Davoe - Sunday, Jan 18, 2004 at 09:18

Sunday, Jan 18, 2004 at 09:18
Coolant has to be used at 33 to 50% to be effective ethelyne glycol being the active ingredient. At 60g a litre it will be useless you need to buy concentrated coolant containing about 965g/l ethylene glycol and mix it with demin water at a rate of between 33 and 50% (50% is best) not cheap but you are usually wasting your money with premix
FollowupID: 305704

Follow Up By: V8troopie - Monday, Jan 19, 2004 at 02:06

Monday, Jan 19, 2004 at 02:06
Well, that depends entirely on your definition of "useless".
For your information, I have used a saimilar coolant for about 150,000k in my troopie now and it still has the original radiator core. They did fit a larger header tank to it with the V8 conversion.
I live in Perth, it never freezes here.
When I did a 20,000k trip around OZ I did replace the coolant with one that had a higher glycol concentration since I went up the Canning- and it does get cold out there in winter- as well as driving over the Australian alps.
So, what may seem useless to you was entirely satisfactory for my troopie's radiator for the last 14 years. No point putting in expensive coolant into an old car like mine.
I feel sorry for those owners of alu radiators who have to go trough, apparently, lots of bother and testing with them. grin.

FollowupID: 305758

Follow Up By: Davoe - Monday, Jan 19, 2004 at 03:11

Monday, Jan 19, 2004 at 03:11
By useless I mean at 6% concentration it will have little effect on the freezing/boiling point of your radiator. Freezing is not a major factor here in oz and if you have a good cooling system you can run your car on straight water with just a corrosion inhibitor without it boiling. Next time you are in your auto shop check out the back of concentrated coolant from valvoline and it should show you the difference it will make to the boiling point of your radiator at 33% and 50% From memory at 50% it is about 130deg so if you have one of these 4.2td patrols for instance that start getting warm during hard work a good coolant at maximum concentration would be essential.
FollowupID: 305760

Reply By: Member - Paul- Sunday, Jan 18, 2004 at 07:07

Sunday, Jan 18, 2004 at 07:07
Probally not a valid test. Distilled or demineralised water does not conduct or should not conduct electricity. I have heard of heater cores corroding when they are isolated from the chassis and have potential. An electrolisis path is set up via the coolant causing corrosion. A more valid test would be to connect one meter probe to the neg battery and the other to metalic objects in the coolant path, eg. radiator core, heater core, control valves etc. before coolant flushing and after refill. If voltage detected connect return conductors to chassis and retest. Draining and refilling the coolant annually ensures the coolant retains its effectiveness and reduces conduction within the coolant path. Anywhere an object containing disimilar metals is immersed in a conductive liquid, corrosion will take place. Very much like a battery. Outboard motors use sacrifical anodes to counter-act a similar effect. The statement "never mix two brands of coolant" may be misleading. Perhaps "never mix different types of coolant" would be more relative.

Regards Paul
AnswerID: 43401

Follow Up By: Rick Blaine - Sunday, Jan 18, 2004 at 09:45

Sunday, Jan 18, 2004 at 09:45
Very Interesting... I'm with you on this one Paul...and it has coincidentally answered a question that was on the list to ask next time my Jackeroo went in for waranty repairs....What is the composition of the anode in the head of the T/D Jackeroo???must be magnesuim and why does this engine have it?? all good grist for the mill.
FollowupID: 305708

Follow Up By: Member - Eskimo - Sunday, Jan 18, 2004 at 09:50

Sunday, Jan 18, 2004 at 09:50
"sacrifical" anodes are self explanatory.
Wow! am I cute
If yer ain't fishing, Yer ain't livin
FollowupID: 305709

Reply By: Member - Eskimo - Sunday, Jan 18, 2004 at 09:56

Sunday, Jan 18, 2004 at 09:56
Yep agree entirely
Had a Adelaidian 4wd service co replace the coolant during 40k service and 20 k later the rad was stuffed. Radiator experts (3 off) believed that old coolant was not flushed from system.

Heater core also went!

Wow! am I cute
If yer ain't fishing, Yer ain't livin
AnswerID: 43412

Follow Up By: Davoe - Monday, Jan 19, 2004 at 03:21

Monday, Jan 19, 2004 at 03:21
I have witnesed mechanics using tap water to mix with the coolant and having lived in Adelaide I can assure you that wouldnt be the best thing
FollowupID: 305761

Reply By: Willem - Sunday, Jan 18, 2004 at 21:46

Sunday, Jan 18, 2004 at 21:46
Because coolant/inhibitors from different manufactures have different chemical compounds, which may adversely react if mixed,................

I will put the emphasis on 'MAY'....there seems to be no hard and fast rule. If the MAY does eventuate then there could be a problem.

I did exactly what your supplied information said not to do. I do not know what brand of coolant was in the car(Commodore V6) but I drained it anyway and topped up with new specified by Holden coolant. No flush no nothing......That was 12 months ago and I have driven 40,000km thereabouts since then.

I suppose I will have to wait and see if the how long before the radiator karks it.
Life is becoming far too technical...thank goodness my old Datsun G60 doesn't have those problems.


Always going somewhere
AnswerID: 43450

Reply By: jemima puddle duck - Sunday, Jan 18, 2004 at 22:30

Sunday, Jan 18, 2004 at 22:30
pretty sure i read a very similar write up in a vacc pamphlet they sent out.you reckon your cute
but im a lot cuter

AnswerID: 43461

Reply By: Truckster (Vic) - Sunday, Jan 18, 2004 at 23:05

Sunday, Jan 18, 2004 at 23:05
Its interesting, When I worked for Chemtrans, I used to deliver tanker loads to a place in Hoxton Park in Sydneys West, from ICI in Botany.. They used to bottle coolant for several large companies.. Inc Servo *SOME* brands...

If I remember there were 3 machines that the bottles went along for filling, and one tank we used to fill out the back of the factory, so coming from this, I can only suggest that the same stuff went into most bottles, with dye added to it..
AnswerID: 43466

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