Electolysis in the <span class="highlight">radiator</span>

Hey kev no it doesn't. Usually its an earth but this one has me atm with what i've done...

"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.

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.

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?

Cheers,
Geoff

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.

Thanks Phil,

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

Cheers,
Geoff

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.

Cheers,
Geoff

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.

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!!

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.