Hi Venderee , I would be more inclined to think it is electrolysis causing the problem.Some years ago my work vehicle was a Nissan 200B,on the inside of the thermostat housing was an anode ,it had been totally eaten away,which was not replaced during the service,the radiator became as you say brittle and sprung leaks near the top tank.Fluids passing thru dissimilar metals will create a small electrical current that will erode metal(electolysis).The fluid used (coolant)in modern motors is designed to reduce this problem,but unless the whole motor cooling system is made from the same metal,electolysis will occur.It may be possible also that the radiator had got to hot at some stage in it's life which can have a similar result,or a combination of heat and electrolysis.There's not much you can do to prevent the problems,I have known aluminium radiators to last four years just out of warranty on a lot of vehicles......cheers Peter
-- Edited by 2foot6 on Friday 20th of June 2014 10:51:30 PM
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SOME POLITICIANS AND BABIES NAPPIES SHOULD BE CHANGED OFTEN FOR THE SAME REASON.
Yes temperature can create a charge over the junction of dissimilar metals thats what a thermocouple is this can cause electrolysis. I seem to recall on aircraft we made sure metal parts are "grounded" to each other.
Also on our racing cars we used to interconnect radiator, engine and body with a grounding strap to make sure no current would trickle around and cause corrosion.
On the Galvanic scale Aluminium is way down below steel and will sacrifice like a bitch.....
There's some interesting articles around on the net regarding this subject and "stray current" One car builder I know of destroyed a brand new Ally radiator in 5 weeks with stray currents present in his vehicle. I built a car that had the battery go flat in a week and on checking I had 136 mA flowing in the system with everything turned off. Turned out to be a faulty diode pack in the alternator. Also don't discount the wrong radiator coolant, some of them are VERY ordinary. I have grounded the ally rad to the frame in my current build.
Actually the solution is not as simple as some would believe
"Stray" currents are not due to electrolysis
They are due current flowing through the coolant from the engine block or some elecrical item mounted on radiator to the vehicle frame[due to bad connections or poor earthing of the deviceDIRECT to the vehicle frame]
.Earthing the raditor can actually make the situation worse
What needs to be done is find out what is leading to that leakage current & CURING THE CAUSE
Electrolysis can occur within the radiator itself if there are dissimilar metals[ seperated enough on thegalvanic scale to generate a voltage]which then need a closed circuit with those two dissimilar metals
Earthing to the vehicle frame will have no effect on that problem but could bring STRAY currents into the situation
THe engine block & the radiato rcan form such a system ,with the coolant as Electrolyte, BUT current cannot flow unless the engine block a radiator are interconnected
Earthing to the vehicle frame will just make that current path easier AND could bring" STRAY" currents into the situation
Best practise is to not have ANY Electrics mounted on the radiator or its actual mountings
Kep the radiator completely insulated from chassis & the Neg wiring
PeterQ
-- Edited by oldtrack123 on Sunday 22nd of June 2014 04:11:35 PM
There's some interesting articles around on the net regarding this subject and "stray current" One car builder I know of destroyed a brand new Ally radiator in 5 weeks with stray currents present in his vehicle. I built a car that had the battery go flat in a week and on checking I had 136 mA flowing in the system with everything turned off. Turned out to be a faulty diode pack in the alternator. Also don't discount the wrong radiator coolant, some of them are VERY ordinary. I have grounded the ally rad to the frame in my current build.
Regards,
Mike.
HI Mike
YES that was a true case of "STRAY "currents
But I would not be earthing that radiator ,If you get another true stray current it will just have an easier path to go through the coolant then the radiator it self, to earth
With the radiotor fully insulated from the vehicle frame ,& the system NEG, Stray curents do not have a path
PeterQ
-- Edited by oldtrack123 on Sunday 22nd of June 2014 04:11:12 PM
The car that gave me the problem had a Brass/copper Rad, so didn't affect the radiator. MY current car has a PWM Ally rad (not cheap) which is not insulated from the frame. You make a good point, the car is currently dismantled so I'll insulate it when I put everything back together again. One point that is made again and again in the articles around is to use demineralised water, as the salts in tap water can break down a lot of coolents enabeling corrosion to take place, and Ally corrodes very quickly.
If the chassis, block and rad are all interconnected at the same ground can someone explain to me how there can be some mystery potential difference between them?
If the chassis, block and rad are all interconnected at the same ground can someone explain to me how there can be some mystery potential difference between them?
HI
Corrosion can be due to EITHER "stray" electrical currents OR the dissimiar metal[galvanic] effect.
To mimize stray currents,each piece of equipment needs to have very good clean Connections to neg/[frameh & ADEQUATE sizes cables .
If the aboveis not adequate, shunt currents can flow through other paths
That is the trap with having any electrical equipment directly mounted on any part of the radiator
Such equipment SHOULD have it's own DIRECT NEG to the MAIN frame or Battery NEG
Galvanic currents require a closed circuit
The radiator being connected to the frame & the engine block also being connected to the frame makes that closed circuit.
PeterQ
-- Edited by oldtrack123 on Monday 23rd of June 2014 10:39:13 AM
The engine has elect current all over it such as ignition etc even if radiator is earthed .. The coolant is the conduit inside the radiator . A lot of engines have issues with spiking voltages. Often caused by not effective enough equal potential bonding between body and motor.. Same thing happens on a house when mains neutral breaks away.. The mains water pipe corrodes bad! Really obvious with copper pipes.. In a vehicle it doesn't take much voltage to cause issues over time.. Good coolant helps ..
