Electrolysis in Alloy Radiators

[hybrid 1039]

Silly me,

For those of you that know my car I have done an engine swap and shelled out for a Fluidyne e36 alloy radiator. For the past 4 years its been working very well, no issues.

A few months back I flushed the radiator in the e30. The e30 doesn't get a lot of miles on it, but I was taking it on a trip down south so thought it was a good time to do the oil and water.

Drained the radiator and refilled with run of the mill super cheap 'quality' coolant and standard water. Followed the mixture on the side of the bottle to the letter.

The past few days ive been driving the e30 in good weather decided this afternoon to lift the bonnet and too my horror the radiator core fins are seeping under pressure where they meet the end tanks. I measured the voltage between the radiator and earth point on the car and hello, 0.5 volts hot. Dammit!

I immediately remembered when I installed the radiator having a long conversation with crazy arab and the trouble he had with his custom alloy radiator on his m62 v8/e30 .. he'd been back to get his radiator welded up with it doing a similar thing. Electrolysis was to blame.

Now I haven't been to total bunny, I did indeed make sure that my radiator wasn't earthing against the chassis. Its been isolated with rubber mounts and there is no continuity running between it and the grounded chassis.

Back when I installed it I tried to find some articles on the subject, only to find that not much was written about it. However after a bit of research today ... I have found a very interesting write up from Denso, one of the largest manufactures of radiators around.

Basically my big mistake was using tap water. I have a iron block (s50bXX) and an alloy radiator with mildly acidic tap water acting is one big battery.

Time for a new radiator for me.. poos.

Radiator failure information from Denso & NRMA.

Premature radiator failure-/causes.

Corrosion ¬- Internal and External.

Erosion - Internal and External.

Stray Current - Electrolysis Internal- External.

Mechanical Damage - External.

Stray currents cause premature corrosion failures in radiators, water pumps and thermostat housings as well as premature ageing in coolant hoses. When we say premature, we mean in as little as three months.

NRMA Insurance did a front end repair on a VW Golf in which the radiator was replaced, three months after the owner took delivery it was found that the new radiator was so badly corroded it was irreparable. The radiator core was dismantled and showed evidence of extensive electrolysis and mixed coolants.

Do’s and Don’ts:

•Never mix different brands of coolants or inhibitors. Mixture of incompatible coolants can induce radiator fouling and can reduce the corrosion protection of the coolant. Always flush out the cold coolant.

•Never use coolants that foam as this will lead to increased cavitation erosion of the water pump. Shake the bottle of coolant then let it stand for 5 seconds, if the foam has broken and the fluid has returned to normal then it probably won’t foam in the cooling system. If the foam has not broken after 5 seconds then it might pay to find another product.

•Never under treat a cooling system as the incorrect ratio of coolant can actually increase the corrosion rate to above that of plain water.

•Only use the best quality water. De-mineralised is the best, never use bore or spring water.

•Always check for stray electrical current in the cooling system.

•If the vehicle is within the new vehicle warranty period, always use the manufacturer’s recommended coolant as to do otherwise could void the warranty should the cooling system fail.

•Always use the service stickers supplied by the coolant manufacturer to avoid any confusion as to which type of coolant is in the system when a top up is required.

•Always dispose of used coolants correctly. All used coolants will contain heavy metals irrespective of their claims of being environmentally friendly.

“Whilst not wanting to pick on any one area of the automotive industry, our own experience tells us that many vehicles we have examined for electrolysis and chemical corrosion damage are those that have had recent paint and panel repairs. If you suspect that a radiator has failed from electrolysis and you can’t find any apparent reason for it, look for signs of recent repairs (keep in mind that the problems can exist right from the time the vehicle was manufactured)

If you spot repairs, be wary of earth wires that:

1. Are not connected.

2. Are loose, corroded or insecure.

3. Earth wire mounting points have recently been painted, thus paint may be down the threaded holes causing poor earth contact.

4. Whist 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 check for any increase in voltage readings in your multimeter

5. Also, turn on as many accessories as you can to load the vehicle’s electrical system whilst monitoring stray current.

6. Check battery cables and mid cable securing points for corrosion and tightness.

Testing for Stray Current:

Using your multimeter, connect one lead to negative side of battery and then with a test probe immersed in the coolant, make sure it doesn’t touch the core and for a proper reading the probe must stay in the same place in the neck at all times. If a current measuring above 50mv is present you then have to start looking for the source.

At this point, we have to say that if you have found a problem relative to the stray current, CHANGE THE COOLANT. Unfortunately we have found with some brands of coolant that their chemical composition does not allow them to dissipate the charged oxygen hat has resulted from stray current, so if you are unaware of the coolant in the system, flush it and replace it.

Common Sources of Stray Current.

•Ford Laser: Multi earth plugs located at the front of both chassis rails, Check the thermo fan earth circuit.

•Ford Falcon: Main battery earth cable fitting at the engine block. Wiring harness fitting at the right front inner guard.

•Holden Commodore: Main battery earth cable fitting at the engine block. Rear stop light wiring harness earths. Earthing point located behind right front headlight.

•Nissan Pulsar: Brown coloured earth cables attached to right side rear cylinder head bolt. ECU earth. Earth circuit for thermo fan.

•Early Hyundai’s: Multi earth wire point located at left front inner guard, cut this off and replace with eyelet connectors.

•Sigma/Magna: Main battery earth cable (both ends)

•Nissan Skyline/Pintara: Air conditioning fan earth circuit, change from condenser mounting to adjoining radiator support panel threaded hole.

Unfortunately, in recent times we are coming across more and more cooling systems and engine failures associated with chemical corrosion. It is a problem common with poor quality inhibitors, low dosages of inhibitor, but we see many where different brands of inhibitors have been mixed and the results are catastrophic.

The mixing of different brands can degenerate into the formation of a chemical cocktail, which can strip metal away with amazing speed.

The internals will show a dark Grey or black discolouration. You can also try removing the radiator cap and feeling the top of the core tubes, they will feel flexible, even soft to touch.

Where this indication is present you may also find items such as thermostat housings and water pumps showing signs of cavitation.

Where chemical corrosion has occurred, quite often the cooling systems components such as the thermostat housing, water pump, heater and coolant pipes will be badly discoloured.

Chemical corrosion can also lead to the formation of small hard deposits of metals and rust within the radiator or engine block causing hard to find overheating problems. These deposits can be very hard to shift if they have been building up over a period of time and as such, become firmly lodged in coolant tubes and within water passages, etc. Keep in mind that 1.6mm of corrosion build up on aluminium causes as much heat retardation as 10.4mm of cast iron.

Mixing of coolants and even poor quality coolants can cause foaming and it’s the introduction of oxygen that leads to the formation of air bubbles that create their own version of cavitation erosion.

The bubbles or vapours, which result from the chemical activity, continually explode against the engine’s hot spots and if not caught early can completely destroy an engine. The exploding bubbles of air cause a hammering effect on the metal gradually eroding away that area and eventually forming a small pin hole. Often a large piece of metal will simply disappear from within the engine. Cavitation can be particularly harsh on cylinder liners and their seals and at different points of the cylinder head and gasket.

Stop Press

Don’t assume that fitting an earth wire directly to the radiator core is a fix all, We did a test on an aluminium core and the wire actually increased the current.

Stray Current explanation & testing procedure:

In simple terms stray current is a chemical/electrical process which causes an electrical current to pass through a vehicles cooling system fluid. It can cause rapid damage to radiators and will indirectly cause problems with other engine components such as water pumps, thermostat housings, etc.

This is brought about when one or more items such as a cooling fan or headlamp develops a problem in its electrical circuitry. This causes an electrical current to seek out an earth path via the radiator core through the engine coolant.

•Remove the radiator cap and run the engine to operating temperature. Do not rev the engine as this may cause the coolant to aerate. Note: Removing the cap will reduce the boiling point of the coolant. This may result in electric cooling fans not operating on some vehicles,

•Switch ON all electrical items including Items such as a mobile phone, rear demister, driving lights, etc.

•Switch an analogue multi-meter to a scale of 5 volts DC or less. Ideally the meter should be capable of reading millivolts. Do not use a digital multi-meter, as its internal operating characteristics are not suitable for this test.

•Place the negative lead of the multi-meter on the battery negative post.

•Dip the positive lead into the coolant without touching the filler neck or the core of the radiator

•A reading of more than .05 volts indicates the presence of a potentially damaging stray current passing through the coolant. Ideally the voltage should be 0 volts, however it is highly possible that some voltage level will be detected

•If no voltage or a very low voltage is detected, carry out the same test as in point 4, but with the ignition OFF.

•If voltage is detected, isolate the circuit by turning all electrical items OFF and switching each circuit ON individually.

Caution:

Refilling a cooling system with coolant will itself generate a current that lasts approximately twelve hours.

This can be avoided by refilling a repaired vehicle, for example, with clean water and then proceeding to test for stray current.

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.

Procedure:

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.

And/or:

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 under-dosing 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.

[euroriffic 595]

Just goes to show it pays to use the BMW coolant and demineralised water. Which I found cheaper that off the shelf stuff anyway.

[yng_750 247]

doesnt go to show anything about bmw coolant really if you actually think about it.

all coolants would perform the same in that situation.

demineralised water is cheap as chips.

I have had an e34 where the head had no coolant galleries left in it due to them using bore water which clogged it with calcium deposits on the alloy.

earthed radiators deteriorate when your car is running and flowing electricity.

Chemical issues such as this work away at it 24/7.

[Michael. 2312]

Mmmm interesting read Josh.

I've always been quite aware of such issues, stick to genuine Toyota coolant and use demineralised water only.

I must check if my radiator is grounded at all... It shouldn't be.

[euroriffic 595]

Was more referring to the info Josh posted about the coolant and how the cheaper stuff will froth up and can cause Air bubbles throughout water galleries and cause erosion.

[hybrid 1039]

Ill do a before and after video on it and show the voltage differences hot and cold.

I actually used the proper water the first time around. This has only happened in 2 months and a total lapse of judgement on my part. That's how bad it is if you get it wrong. $1080 down the drain.

[kiwi535 538]

can you use a sacrifical anode to delay this happening?

[hybrid 1039]

Yeah.. the key however is to stop the chemical process. I measured it stone cold this morning and it was 30 millivolts which is what it should be. Anything over 150mv is bad. The cause for me is definitely static build up in the ionized (tap) water.

At least ive passed my 101 chemistry battery making project

[yng_750 247]

im surprised bmw havent invented a volatage sensor for the coolant system to tell you if you are generating power haha.

[yng_750 247]

Just as a side note you can do the same voltage test on brake fluid to see if a galvanic reaction is occuring due to excessive water levels in the fluid.

any reading over 0.300 volts is excessive

[kiwi535 538]

whats the disimmalr metals...alloy and alloy or are we talking cars wiith iron blocks and alloy rads?.

[yng_750 247]

generally iron blocks and alloy radiators but can be brass water pump impellers etc.

just remember it doesn't disappear any alloy that wears off the radiator is being deposited somewhere on the engine.

not enough to make a difference mind you

[Allanw 1051]

in addition to the above.

I dunno what your tap water is like, but the Whangarei District Council supply is very good - I know somewhere in the BMW TIS it has the requirements of the water to mix with coolant, and it's pretty good. I've used it an a number of cars over the years, with alloy radiators, but the factory type with plastic tanks etc. I'm lucky enough to have tank water now though

People get some funny ideas about water. I'm in Clinical Engineering at the Hopsital up here, and we have a LOT to do with the water for Dialysis, but am certainly no chemical engineer.

People seem to think that water with "nothing" in it is the way to go for cooling systems... it's NOT!

Water is called the "universal solvent", because it want's to dissolve things into itself. The emptier it is, the better it is at disolving things.

"Pure water", as you'd get from a good Reverse Osmosis (RO) unit, isn't corrosive... BUT it's SO empty, it will dissolve anything it can - it actually pulls any Ions it can - metal pipework literally washes away. I've actually seen people on forums recommending RO water for cooling! Our RO's take in tap water with a conductivity of about 300us and put out "pure water" at about 3us. Prior to the RO, the tap water is softened and filtered. You'd be amazed at how quickly this stuff can dissolve things. The big chunky salt we use in the water softeners dissolves almost instantly in RO water, but not so much in tap water

Some of the issue may be the alloy used in the radiators too - just because it's an aluminium radiator, doesn't mean it's made of aluminium - it is an Alloy of metals, and some can be more or less noble, depending on the mixture used.

Also, as the antifreeze/coolant is "used up", it actually BECOMES corrosive - the PH drops over time. The harder it's working to fight corrosion, the faster it's used up. (usually over a longer time than in the OP though!)

[hybrid 1039]

Im going to be using my data logger to measure the before and after. I can measure 0-5volt calibrated to millivolts and same ground points so DC offset wont be an issue, so will be easy to get a reading and how bad it gets as the water heats up .. or more importantly the more the static electricity builds up in the water.

I will log before with tap water and old radiator and after with demineralised water with new radiator both alloy.

[Ultrarandom 3]

I've always been told to do the opposite and specifically earth the radiator to prevent electrolysis because the water running through builds up static charge which then doesn't get relieved unless it is earthed.
Had this done in my old Skyline and had no problems with it, not sure if BMWs are different but I also know this is the case with Fords (was people from Ford dealerships who told me about it).

[hybrid 1039]

See the problem is I kind of agree with you, but when the water pump has been running for a period of time the charge its holding is 500millivolts. (0.5volts) When the car is stone cold and sitting for 12 hours its back to 30millvolts or 0.03 volts.

Only two things different. fluid is hot and under pressure (80-90 degrees c), The water pump has been running.

Why is it generating electricity when you run the motor? (engine head and block are both earthed and radiator is isolated)

I do understand that I probably have either a slightly acidic or alkaline ph level as the catalyst.

Again, i'm going to replace the radiator and fluid and data log it to show the differences.

[yng_750 247]

chemical reactions increase with temperature

[kiwi535 538]

my opinion always has been that there is little wrong with NZ tap water for radiators with appropriate anti freeze levels

Edited November 2, 2013 by kiwi535

[EuroSurgeon 2]

my opinion always has been that there is little wrong with NZ tap water for radiators with appropriate anti freeze levels

Have been putting in tap water for years with genuine bmw coolant, never had one return with corrosion issues

[hybrid 1039]

I understand I have a different than normal setup. Iron block and alloy radiator.
Interesting about the temp thing causing more of the reaction.

Thanks ron that explains a lot actually.

Again .. data logging will show all here including when the thermostat opens, should register a exponential rise in voltage at the point of open.

[hybrid 1039]

Joe I think you have been dealing with partial alloy radiators and mainly alloy block cars?
Chemically the antifreeze coolant ive been using is probably no where as good ph balamced as the
Oem stuff. Also full of dye.
I do know that previously the difference has been the water I have used.

[MLM 57]

See the problem is I kind of agree with you, but when the water pump has been running for a period of time the charge its holding is 500millivolts. (0.5volts) When the car is stone cold and sitting for 12 hours its back to 30millvolts or 0.03 volts.

Only two things different. fluid is hot and under pressure (80-90 degrees c), The water pump has been running.

Why is it generating electricity when you run the motor? (engine head and block are both earthed and radiator is isolated)

I do understand that I probably have either a slightly acidic or alkaline ph level as the catalyst.

Again, i'm going to replace the radiator and fluid and data log it to show the differences.

Are both measurements with the motor runniing and the same electrical things running?

This prompted me to read arround a bit (got nerd sniped again) ant it seems there are two drivers, galvanic corrosion potential defference and electrical loss in the system. The potential difference of iron to ally is about 0.05-0.1mv. While temp and flow effects this and may explain the .5V your seeing when hot, the test conditions are important too. Ie if the door was open and the interior light on for one measurement it may upset the result.

Sounds like your going to log voltage on a warming car which is excellent and should reveal alot.

[EuroSurgeon 2]

Joe I think you have been dealing with partial alloy radiators and mainly alloy block cars?

Chemically the antifreeze coolant ive been using is probably no where as good ph balamced as the

Oem stuff. Also full of dye.

I do know that previously the difference has been the water I have used.

Yes mostly partial alloy, but many complete alloy, we used to have alot of issues when using non genuine, especially with OAT coolant like shell coolguard, moved to genuine and issues seemed to disapear

[Lubed 55]

Has the radiator been opened up and inspected internally to confirm to your theory of the damage? is it possible it may be a different fault?

[yng_750 247]

unrelated to this but to explain why you shouldn't ground out an alloy radiator.

the biggest part that throws people off is that electricity actually flows from negative to positive not the other way around.
so when a radiator is grounded as alloy its very easy for electricity to flow out of the chassis through the radiator and into the engine.

when it flows like this it takes particles of alloy away eventually eating away at the metal.

this is much much worse when you have the normal ground cable damaged or disconnected.

i have seen an mr2 try to catch fire due to the main ground strap being left off during an engine change and the engine grounded through the throttle cable which got glowing hot very quickly.