Electrolosis Q's

[3gress]

I have a mishimoto radiator with welded AN bungs and nylon braided stainless hose to the electric water pump setup. Also the (brass?) temperature sensors for ewp controller and adaptronic are fitted into rad top tank.
I am concerned about the dissimilar metals causing electrolosis issues and possibly stray currents going through the braided lines as they have a stainless braided inner layer that may make contact at the hose end fittings.
Researching the topic only causes confusion with some suggesting grounding the rad, others advising to isolate it and do the usual stray current tests along with alot of conflicting opinions.
I was planning on fitting a zinc sacrificial anode as a stop-gap measure but would like to ask for thoughts on the matter.
Another issue is the standard temp sensor for the dash gauge grounds through the sensor body and initial plans were to fit this direct to radiator top tank also.
With the reverse flow coolant setup i cannot use the fittings available in the head to mount sensors for accurate temperature measurement and finding somewhere to mount the three needed temperature sensors is a big problem at present.
Thoughts?

[bruce]

Lokiel has thought this through and fitted an anode.

[project.r.racing]

I've never seen anything other than the cast iron parts (eg the block) inside of an engine bay rust. And normally with some regular running (which has electrolosis as the running process) as the block and many parts inside the bay are earthed. I'm doubt you'd have an issue. You just rattle off numerous metals that are used due to the ability to withstand rust forming.

[3gress]

Thanks for the responses guys.
Would it cause issues if i grounded the radiator to chassis and fitted the dash temp gauge sensor to rad top tank? The sensor is a single wire that grounds through the threads.
General consesus across the web is to ground the rad so it has an identical electrical charge to block and chassis.
Brass and aluminium contacting will corrode with time especially with moisture and the aluminum will fail first which means wrecking the radiator quickly. Add stray current and it supercharges the process.
I will look toward fitting two or more sacrificial anodes in the coolant plumbing to avoid radiator or head corrosion i guess and hope for the best

[Lokiel]

Lokiel has thought this through and fitted an anode.

I installed the TSE Crossflow radiator which needs a barb for the overflow tank hose.

Apparently the radiator ships with one but I couldn't find it so I e-mailed Andrew (Savington) if I could use a brass fitting that I had on hand and would this cause any electrolysis issues.

Andrew said it shouldn't be an issue and that the TSE radiator cap with it's sacrificial anode would handle that anyway (see http://www.trackspeedengineering.com/Cooling/trackspeed-radiator-cap.html).

I ended up buying an aluminium barb and using that since I had to buy a few other bits & pieces at the time - it's an expensive radiator so I figured it's all good insurance.

[97 MXV]

Hey 3gress your under bonnet looking good ! Engine brace is brilliantly mounted to body so neatly.
I like to hark back to some basics about corrosion starting with the nobility of metals working what is sacrificial to what and how long in time that sacrifice would actually take, given the presence of strong oxidizing layers, voltage gradient, stray currents and chemical concentrations of inhibitors and water purity (presence of high PH mineral salt sodium and calcium hydroxides which love to eat aluminium).

But more fun is a golden opportunity for some underbonnet bling in the process. Imagine the under bonnet eye candy of a rats nest of Earthing Cables loved by the Japs.



and even a Polariser loved by the Aussies !


and now a sacrificial anode in the radiator cap loved by the Yanks !


Obviously all these things are good if they pass appropriate tests of significance. Otherwise they are a placebo or nice bling with internet bragging rights included in the price.

First up should there not be some kind of focus on what is failing, and work the Problem starting with dumb questions rather than guessing Solutions as there can be many Solutions to a Problem, a few Solutions proving significant, while the myriad of other Solutions placebos.

Dumb questions might be, is the issue electrolysis from faulty circuit earth leakage rather than simply galvanic corrosion of dissimilar metals due to their relative nobility on Periodic Table ? Aluminium usually is protected by its oxide layer normally...what is happening to it and can it reform in the presence of oxidizing agents and in crevices ? The presence of refreshing oxygen in the coolant passing over the surfaces inside the radiator is probably a good thing. (Stagnant flow a bad thing.)

Now with electrical currents causing electrolysis than a sacrificial anode is sending zinc somewhere to complete the circuit isn't it ?....where ?...and what happens when the zinc runs out ?. Sounds dodgy if it needs anodes.

Speaking of zinc anodes, exposed aluminium dissolves in alkaline environments (high PH) whereas exposed zinc dissolves in acidic environments (low PH) What is the PH of the coolant proposed ? I imagine you might want a PH a touch lower than 7.2 for aluminium but that may not suit zinc. Mineral salts (Sodium and Calcium) in water used to mix coolant may be an issue for aluminium. Premix would be the answer to that I assume.

3gress, are such questions answered in your research so far on aluminium radiators vs zinc anodes vs stray currents ?

[3gress]

Always enjoy your links Keith.
With the exorbitant price of polarizer boxes these days i can count that option out .
The two issues i can see are first the reaction between the brass alloy temp sensors and aluminium radiator.
Secondly stray currents through the AN fittings and stainless braided line.
Assuming PH concerns are taken care of by using premix with corrosion inhibitor additives and distilled water, i cannot find any definative advice on how to protect the radiator from corroding.
The sacrificial anode would simply be there to corrode first but what type to use, zinc alloy or such?
Should I earth the radiator? This would allow me to fit the one wire temp gauge sensor in rad.
I can't have my awesome revlimiter gauges not fully working.
On a good note i found how to spell 'electrolysis' and identified my rad as a koyorad and not mishimoto!

[97 MXV]

3gress this is amateur attempt to address problems you raised:

The idea is to accept that current will always be in the coolant, but levels kept so low and electrolysis so slow that the sun will run out of hydrogen before the radiator rots out. This is because resistance through coolant much greater than through any available metal path.

Remember some MX5 radiators with plastic tanks are rubber mounted so rubber mounting an alloy tank radiator and putting current into the tanks through brass sendors with the only path to ground being via the coolant path with the engine is bound to have issues.

With regard to the brass fittings in the alloy rad, I would try and use a waterproof thread sealant compound that keeps the coolant out of the thread area, keeping that crevice area "dry" enough to slow corrosion to practically zero.

With regard to the single wire sensors grounding through the rad, if the current is significant, ensure the rad is properly grounded and the fitting grounded to the radiator or separately grounded. The idea would be to ensure any current path is via a dry path metal to metal with zero resistance so keeping most of that current out of coolant.

With regard to the braided hose if the radiator is grounded, and the engine is grounded then the zero resistance braid is not carrying any potential so any current will likely not go into coolant where resistance is higher....happy days

[bruce]

I changed the anode in my house hot water heater. It's a 1.1 metre rod. The old one was almost completely gone.
I bet no one else has done it.

[3gress]

Aeroflow offer a zinc anode plug with 1/4"npt thread, part no. #AF49-2500.
Along with Keiths' suggestions, a couple of these fitted into the rad' might be the go.

[97 MXV]

OMG my suggestions were intended to provide a low cost way to avoid the high cost of fitting anodes to a radiator, not as a reason to spend good money on modifying the rad for them.

It might not be worth the bragging rights to modify and pressure test a rad to make it anode friendly for anodes when we know such anodes will be deprived of most of their relevance by nice and fresh, pure clean electrolysis free coolant, not found in a hot water system.

[3gress]

Too late! Rad' has already had extra bungs welded in some time ago along with pressure testing to ensure no leaks. The rad' had a bung in top tank as standard and i had more added to match threads of the different sensors. The only $ outlay would be the cost of the anode and there is a spare bung for it.
Belt and braces eh'?

[97 MXV]

Belt and braces eh'?

Tragic the lengths some go to to keep their ar$e covered.

[Jaspers dad]

I would think that as zinc is so close to aluminium on the scale that a zinc anode, while it would do no harm, would be of dubious value. If it were me, i would ensure that I used distilled water with the glycol as the coolant and do all that I could to insulate the brass from the aluminum by finding,if possible, another place for it or,if not to use a good quality PTFE tape,such as the yellow ones used for gas, carefully put on so as there is just two thicknesses and in the direction of the thread so that it doesn't wind itself off. I would also keep the radiator isolated above earth if possible.

[97 MXV]

I would think that as zinc is so close to aluminium on the scale that a zinc anode, while it would do no harm, would be of dubious value.

Very close indeed. If you can believe this chart, it would be the aluminium not the zinc starting off as the anode.
Also brass (Cu) is much more noble than aluminium so aluminium would likely be the one to rot out from electrolysis.

If it were me, i would...do all that I could to insulate the brass from the aluminum by finding,if possible, another place for it or,if not to use a good quality PTFE tape,such as the yellow ones used for gas, carefully put on so as there is just two thicknesses and in the direction of the thread so that it doesn't wind itself off. I would also keep the radiator isolated above earth if possible.

For proper functioning of the sensors, this total insulation approach would require unbraided hose and a separate earth wire from the brass fitting of the sensor to earth, or alternatively remote location of sensors away from insulated radiator as suggested.

So 3gress you now have a couple of approaches, one simple earthed radiator (belt) and this one based on a fully insulated radiator (belt and braces).