"Electrolysis Ate My Matrix" Shock

rg · Unread post by rg » 04 Feb 2003, 18:24

Hello Folks,
Apart from wise advice on changing coolant with deionised water and decent glycol, does anyone have any suggests to stop the electrolytic effect on my 2.5 XM? I have just replaced a small radiator after 40,000 miles. A bit too soon, I think.
rg

tomsheppard · Unread post by **tomsheppard** » 04 Feb 2003, 19:17

Electrolytic corrosion occurs between dissimilar metals with different electropotential voltages. I've had a theory that half filling the coolant with copper Sulphate and fitting a pure copper ring in one of the hoses, connected to battery+ would copper plate the cooling system over the life of the engine. It is a nice idea but a little fanciful. Normal practice is to use a sacrificial anode as is used on boats to ensure that it corrodes before the rest of the boat's skin fittings. What you are looking for is a lump of something even more likely to corrode than aluminium-probably a bit of magnesium bought from a ship's chandler but where to connect it? There's the rub. Maybe the answer lies in the conductivity of the corrosion inhibitor.If the system ran only distilled water,then there would be no conductivity and hence no electrolyte would exist until salts leached out of the metals. check the conductivity of your coolant- You may benefit from running 100% glycol.

tomsheppard · Unread post by **tomsheppard** » 04 Feb 2003, 20:30

Two thoughts by way of follow up. 1. Some suggestions have been made that the matrix should be earthed. If there is voltage between the matrix and the engine block, (test using a good digital multimeter with a 220k Ohm resistor in parallel across the probes) then do it.
2. Modern motorcycles use engine oil as a coolant. I bet they don't corrode...

DLM · Unread post by **DLM** » 05 Feb 2003, 14:30

On the subject of oil in cooling systems, my ex once concluded on a BX16RS that the radiator filler was the correct orifice for topping up the oil being burnt by the worn valve stem seals. I wasn't there to clean up the resulting mess, but the engine survived...

DLM · Unread post by **DLM** » 05 Feb 2003, 14:34

....and the heater matrix that I've just removed from a scrap diesel BX was in good condition apart fom the tube end nearest the driver. This, and only this, had corroded away for reasons I confess I can't fathom.

tomsheppard · Unread post by **tomsheppard** » 05 Feb 2003, 14:48

Probably where the tube is welded on and there is a junction between two dissimilar metals. It is a guaranteed method of getting electrolytic corrosion which is why it is rotten there.

alexx · Unread post by **alexx** » 05 Feb 2003, 15:07

Tom, old-fashioned GS also used engine oil (+ air) as coolant! It's cooling system didn't corrode either.
Edited by - alexx on 05 Feb 2003 10:08:30

batbay · Unread post by **batbay** » 06 Feb 2003, 02:37

Anodes are used in boat engines(as well as in other areas to protect skin fittings,etc). When used in engines the anode sits in the coolant and has no electrical connection. The principle is that the "less noble" anode will protect the rest of the system. The anodes do work, and have to be replaced regularly.