Haven't had much luck with the eBay alloy radiators, have killed 2 in the last 6 months so I've gone with an adrad copper/brass unit. Not sure if they died because of stray currents so I've purchased an analogue multi meter to test the system. Digital multimeters are no good for this test, but basically it's a matter of pulling the radiator cap off, negative probe onto the negative battery terminal and positive probe into the filler neck so it contacts the coolant but not any metallic parts, ie the filler neck. Shouldn't register a voltage of 0.05v or more, otherwise the radiator will have a shortened life span. Done with the engine running and all electrical items on, such as hazards, lights, radios. Etc. If a voltage of 0.05v or more is registered, turning off each electrical item one at a time may isolate the problem and get sorted from there. Just waiting for the multimeter to arrive so I can get to the bottom of this.

Here's the new radiator(again but an adrad one at least)


The 2nd alloy radiator


The first alloy radiator


Both leaked in similar fashion. I was lucky that they were replaced under warranty. Actually they just sent me new units. I ended up selling the 3rd when it arrived.