Electolysis in the radiator

Submitted: Friday, Aug 06, 2010 at 12:40
ThreadID: 80548 Views:5253 Replies:10 FollowUps:10
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Hey guys need some help.. I'm an auto elec and i've getting electrolysis in a mates radiator with a reading of about 5.64v.
Its a toyota hilux with an aluminium radiator with plastic tanks so u know.
What i've done so far:
This is all done without vehicle started
Cleaned all earth connections on the vehicle took ages.
Flushed radiator and put correct coolant mix in..
Removed battery let sit for about 2hrs for discharge still had a reading of 4.35V..
Removed all fuses and disconnected alt from circuit still reading 4.35v..
So now i'm at a lose of what to do maybe reflush the radiator again with distilled water and try again but i'm hopeing someone might have a solution out there.. Never had these problems with the copper head tanks f'n chinese imports...
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Reply By: kev.h - Friday, Aug 06, 2010 at 12:46

Friday, Aug 06, 2010 at 12:46
Does it have electronic rust protection can cause induced stray current
AnswerID: 426347

Follow Up By: bonez - Friday, Aug 06, 2010 at 12:59

Friday, Aug 06, 2010 at 12:59
Hey kev no it doesn't. Usually its an earth but this one has me atm with what i've done...
FollowupID: 696921

Reply By: Time - Friday, Aug 06, 2010 at 13:37

Friday, Aug 06, 2010 at 13:37
Does it have a second battery earthed to the head of the motor rather than earthed to the block?

This can cause electrolysis I'm told.
AnswerID: 426351

Reply By: OzTroopy - Friday, Aug 06, 2010 at 13:43

Friday, Aug 06, 2010 at 13:43
Could check that the radiator is mounted properly i.e.

Insulated from the metal bodywork.

heh heh ... its not chinese imports ... its the vehicle manufacturers choosing the cheapest way of cutting production costs.

.........and aluminium doesnt even lose heat as good as copper/brass.
AnswerID: 426352

Follow Up By: rags - Friday, Aug 06, 2010 at 21:13

Friday, Aug 06, 2010 at 21:13
"and aluminium doesnt even lose heat as good as copper/brass."
I was under the impression that aluminium was more effective for use in cooling in both design principles and metal and why you will only find aluminium radiators used in the likes of V8super cars, off road comp cars etc [but in full alloy construction without the use of plastic tanks].
When i replaced my radiator in a Prado due to failure due to similar electrolysis i was adviced of the benifits of aluminium over copper by a couple of different radiator suppliers of both types, with the only real benefit today in most modern cars of a copper core being is that i can still soldier it if repairs are to be made. I even found that a replacement copper core can be supplied with plastic tanks if desired.So i stuck with the aluminium but have yet to solve this earth leakage problem.
FollowupID: 696981

Follow Up By: OzTroopy - Friday, Aug 06, 2010 at 22:49

Friday, Aug 06, 2010 at 22:49
Fair enough ... Its a bit like patrol and cruiser comparisons.

Check out thermal efficiencies of the metals.

Then factor in windchill, airflow and a bunch of other stuff.

If its a "good" design aluminium radiator ... with huge tubes and good surface area compared with a copper brass radiator for the same vehicle application ... there could well be an improvement.

V8 supercars ??? .... weight advantage ... and electrolysis, corrosion, fatigue etc doesnt worry them as the radiator only has to last one race ...

Off road comp cars ??? ... as above .... also seems to be a growing awareness of short term life in that environment ... again, sponsored competitors wont really care.

e.g..... "XYZ Aluminium Radiator" wins Bathurst or the Dakar ... They will fix it / replace it - as often as needed to keep getting the advertising.

I just replaced a factory aluminium radiator with a dodgy thai made "aussie" adrad copper brass rad replacement... and the old girl has never had such stable, lower temps before.

Agree that a major benefit is the repairability of copper brass over aluminium ... which is my main reason for liking them ..... any mug with a gas axe and a stick of solder can be back on the road in no time ....... And we do all do "expect" to have to repair a copper brass one from time to time.
FollowupID: 697007

Reply By: Member - Phil G (SA) - Friday, Aug 06, 2010 at 14:21

Friday, Aug 06, 2010 at 14:21
Does it have an aftermarket electronic alarm/monitor in the cooling system?
AnswerID: 426357

Follow Up By: Member - Geoff A (VIC) - Friday, Aug 06, 2010 at 20:13

Friday, Aug 06, 2010 at 20:13
Hello Phil,

Could you please elaborate on this?
I recently fitted one of these devices to my GU 4.2td.
Have I done the wrong thing?

FollowupID: 696960

Follow Up By: Member - Phil G (SA) - Friday, Aug 06, 2010 at 22:00

Friday, Aug 06, 2010 at 22:00
Gday Geoff,
Some low coolant alarms tell you they use AC to the probe rather than DC so there is no risk of electrolysis. Have a look at the Redarc site HERE.

If one was fitted you could measure stray current with and without the unit connected.
FollowupID: 696996

Follow Up By: Member - Geoff A (VIC) - Saturday, Aug 07, 2010 at 06:30

Saturday, Aug 07, 2010 at 06:30
Thanks Phil,

Mines not a Redarc, so I think I need to look into this a bit further.

FollowupID: 697029

Follow Up By: Member - Geoff A (VIC) - Saturday, Aug 07, 2010 at 11:08

Saturday, Aug 07, 2010 at 11:08
Phil (and anyone else that's interested),

Here's the reply from the company I got mine from:

"Question: Do low coolant alarms cause damage to radiators & cooling systems and do you use A/C or D/C current

The short answer is we did major research into the subject before going into design & production of our product almost 10 years ago.
Our units will not cause any damage to any cooling system and I don't believe any of our competitors units will either.

The long answer is as follows:
D/C or A/C ?

The most common industrial use of electrolysis is in the electroplating industry.
They always use D/C current as A/C damages the electrolyte (In our case the coolant) and will damage cathode (the work piece)
With D/C the transfer of metal is from the anode to the cathode (probe to engine) with A/C that process is reversed as the frequency oscillates.
So if there was any depletion with a D/C unit it would be the probe that is damaged and not the radiator, the probe would be deposited on the radiator.
So no A/C was the first parameter for our unit.

Incidentally, the coolant is permanently connected to the battery earth via the cylinder head & block so in reality it isn't possible to make it positive
The so called A/C units are not really that at all.

Next what current & voltage to use? (some of each is obviously required to make an electronic warning system)

We evaluated existing designs that had been on the market for many years & found they were using about 170 micro amps.
Obviously they had been used continuously in marine & industrial non stop applications for many years with no adverse effect so we started with
similar values.
Our original test vehicle has been fitted with 4 of these original units with separate, different test probes for
9 years now & is still fine with it's original radiator & thermostat housing so I have full confidence that the 170 micro amps which competitors were using has absolutely no ill effect on a cooling system.
However some 6 years ago we totally redesigned our electronics and reduced our current to typically 45 micro amps at 2 volts.
This is about a quarter of what we were using previously.

The fact is in recent years many radiators have failed within 2 years of being installed & this is because the coolant was not properly flushed before new was put in. Many modern coolants are not compatible with each other and the existing coolant in an engine.
When they are mixed, within a week or two they become acidic and then proceed to attack both the inside of the radiator and alloy parts of the engine.
An oxide of alloy is formed which is borne around the inside of the cooling system by the coolant.
Fortunately for many of our customers, our unit is very sensitive to this layer of oxide which is formed and will give out a much longer test beep & led flash on it's start up test routine, indicating a problem as Willem found out when his radiator was destroyed by mixed coolants.
The existence of this problem can be verified by wiping a finger around the inside of the radiator cap neck.
If there is oxide the finger will come away a dirty grey/black colour.
Only last week we identified this very problem for a dealer on a vehicle in the UK thanks to the fact it was fitted with one of our units prior to sale.
They had changed the coolant without a flush.

Hope I put you mind at rest & answered any questions you have."

I'm happy that mine's OK.

FollowupID: 697047

Reply By: Member - Tour Boy ( Bundy QLD) - Friday, Aug 06, 2010 at 15:39

Friday, Aug 06, 2010 at 15:39
The early TD 100 series had this problem and I think from memory an earth strap from the rad to the block solved it.

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AnswerID: 426362

Follow Up By: Mike DiD - Friday, Aug 06, 2010 at 19:37

Friday, Aug 06, 2010 at 19:37
No way - if there is ANY electrical connection between the Radiator and the rest of the you are shorting out the "battery" formed by the different metals in the radiator and engine, using the coolant as electrolyte - you will have VERY fast electrolytic corrosion.

You need to make sure there is NO connection.
FollowupID: 696957

Reply By: Rockape - Friday, Aug 06, 2010 at 17:20

Friday, Aug 06, 2010 at 17:20
if I read this properly you have disconnected all forms of electrical charge from the vehicle. To produce 4 volts I would think there must be dissimilar metals and the cooling fluid is acting as an electrolyte. Has anything been done to the vehicle (any mods or repairs).

Mate worked on a tramp steamer in New Guinea that had developed terrible electrolysis, turned out to be a new crank that was fitted to the engine was magnetised and producing a charge when spinning. How he tracked it down astounds me still.

Have a good one.
AnswerID: 426365

Follow Up By: bonez - Friday, Aug 06, 2010 at 18:01

Friday, Aug 06, 2010 at 18:01
the only thing i'm aware of is he had some body repairs to the doors and we did the motor a little while ago and this has just happened when he got the new radiator put in (maybe run earths everywhere lol)... Yeah that is outstanding how he found that!!
FollowupID: 696945

Reply By: Eric Experience - Friday, Aug 06, 2010 at 21:09

Friday, Aug 06, 2010 at 21:09
Step one drain the coolant and see if the voltage disappears.
That's shows it is a dissimilar metal problem.
If it is a dissimilar metal problem look for any brass or copper fittings like thermostat, shower heater, cabin heater etc. If its not practical to change the copper fittings use a coolant designed for mixed metals like Fuch. Eric
AnswerID: 426401

Reply By: Rangiephil - Friday, Aug 06, 2010 at 22:44

Friday, Aug 06, 2010 at 22:44
Good reply that took 5 seconds on google.
Regards Philip A
AnswerID: 426421

Reply By: Allan B, Sunshine Coast, - Friday, Aug 06, 2010 at 23:17

Friday, Aug 06, 2010 at 23:17
Hi Bonez,

I doubt that those voltages you are reading are from electrolytic action. The most voltage that can be generated by this is about 2 volts.

Just where are you placing your test-prods to read these voltages?

Is the battery connected during readings? I suggest removing the battery completely from the vehicle during readings.

Because of the dissimilar metals (aluminium radiator, iron engine block) in association with an electrolyte (coolant) a primary cell is formed and a voltage will appear between the two metals (electrodes). For electrolytic corrosion (ion transfer) to occur a completed electrical circuit must exist and while the radiator core sits insulated from the chassis there is no completion of a circuit to allow current to flow even though a potential difference (voltage) exists. So it is VERY IMPORTANT that the radiator core remains insulated from the chassis. DO NOT connect an earth wire to the radiator core.

I would expect a voltage difference between the radiator core and the engine block but only about 1.8 volts and of no concern.

There is a lot of nonsense circulated about radiator electrolysis. Some propose taking voltage readings by inserting voltmeter probes into the radiator coolant. When they do so, the test-probe (being brass or nickel-plated) forms an electrode junction with the coolant electrolyte differing from the other junctions of aluminium or iron and so produces a voltage indication on the meter. It proves nothing at all of consequence.


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AnswerID: 426427

Follow Up By: Plasnart - Saturday, Aug 07, 2010 at 22:00

Saturday, Aug 07, 2010 at 22:00
Absolutely what Allan said (although I couldn't have said it so expertly). Aluminium is sacrificial to mild steel when connected by an electrolyte. A circuit will occur if the different metals are not insulated adequately, so check the radiator mounts/connections to ensure no direct connection between steel/aluminium.
FollowupID: 697118

Reply By: bonez - Tuesday, Aug 10, 2010 at 13:20

Tuesday, Aug 10, 2010 at 13:20
Hey found the problem guys it was in the starter motor even thou i disconnected it it still held voltage in the radiator weird anyways yeah broken wire inside the solenoid on the brush side... It was just touching but the other day could start the ute so pulled the starter off everything looked sweet till i removed the contacts and yeah the pull in wire wasn't attached...
AnswerID: 426830

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