Electrolysis Issue

Hey, after spending quite a bit of time searching over the past few weeks regarding an apparent electrolysis issue with my XJ I figured I'll just ask as I can't seem to find the answers to my question.

I have a 1997 Cherokee (4L, AW4, NP242 if this makes a difference) over the past year I've been having some radiator issues resulting in several replacements under warranty from my local mechanic (unfortunately I don't have enough experience nor the tools/space to do this type of work). They have determined it is an electrolysis issue causing the repeated failure of these radiators.

Though when I measure the voltage difference between my negative battery terminal and coolant overflow bottle I get a voltage reading between -0.1V and -0.2V depending on coolant temperature (Voltmeter's negative probe on neg battery post and voltmeter's positive probe in coolant overflow). Am I incorrect in thinking I don't have an electrolysis issue by having a - voltage reading, or am I measuring it incorrectly?


Thanks for your time!

Have you renewed your grounds?

I've replaced B- to fenderwell and block to firewall with 4AWG. Planning on replacing B- to block as well, just need another warm day to do so but the snow keeps falling.

I was also going to replace the B+ to starter as the reading does temporarily drop to 0 while starting.

Electrolysis Failure ? Que?

I have never heard of that...
What construction is the radiator (plastic tanks/ aluminum core, or copper)?
Where does the radiator leak?

As far as the potential from the coolant to the battery goes...
Frankly, the potential is minimal. As long as the ground strap from the engine to the fire wall is golden, your engine is grounded to the same potential as the radiator support.

I'm trying to recall, but I seem to remember the radiator being isolated from the frame, but it shouldn't make any difference.

-Ron

The radiator was an aluminium core with plastic tanks, I can grab the model number if need be. As per the shop it was pin hole leaks where the aluminium core meets the tanks.

Are you sure your mechanic is not using tap water/antifreeze mix to fill the cooling system? Distilled water/antifreeze mix is recommended with many here. Also, diesel engines have problems with electrolysis I think due to the vibration they make. So there is a cooling additive called supplemental coolant additive (SCA). I would recommend adding this stuff after you flush your coolant out again. I remember when I replaced the heater core on my dodge cummins that the manufacturer would void the warranty if the voltage was .3v or more.

I had a bad block ground from the battery and it ended up using my cooling system to ground itself which at the waterpump.

Sounds to me like they are just shitty radiators.
Order up a single or double core copper one. I know OEM is plastic tanks attached to an aluminum core, but I don't trust them.
Also replace radiator cap with a new one. Over pressuring can cause issues.

I have never used distiller water on radiators, but then except for sandstone, we don't have mineral deposits in the water. Using distiller water eliminates those impurities and is recommended practice.

-Ron

I agree with what's said directly above...... It's possible for a bad head gasket to leak combustion gasses into the cooling system and over pressurize with or without overheating symptoms. Got brown crud in the overflow tank? This is likely not the problem but ya never know...

I would measure the ph of the coolant. A leak of exhaust gas into the coolant will turn it acidic.

You can cure an electrolysis issue by simply grounding the core. A ground strap sandwiched under one of the upper mounts and the other end to body ground will work well.

I had an issue on my last cherokee... I mounted a york compressor for OBA. In doing so, I sectioned the upper rad hose with a piece of brass pipe. Electrolysis at through the pipe in about 6 weeks. Granted it was thin wall but... Anyway, cured it by using a ground strap.

old_man said:

I would measure the ph of the coolant. A leak of exhaust gas into the coolant will turn it acidic.

Click to expand...

Any particular brand / type of PH test strips you would recommend. I was just browsing online and see a huge sway in reviews for different test strips.