I lost my first V12 motor to the eating action of electrolysis, apparently whilst the car sat for a period of time tied up in the legal system (1991-1993).

After I'd had the car for a few months, steam started coming out one of the tailpipes.

The problem was traced to electrolysis eating through the water jacket into the intake manifold ports or the intake ports in a cylinder head, can't remember which as this was 1993-94. Owing to the cost of repair, it was more cost-effective to replace the entire motor with one from a salvage yard.

1. Has anyone else had this occur? Is it common?

2. Is there some way to prevent this from occurring? I've got a fresh 1986 motor in the car now, and don't want this to happen. Currently, I disconnect the negative lead from the battery whenever the car is stored, but I don't know if this has anything to do with this kind of electrolysis or not.

Thanks for all input.

Lou

 

Lou, it sounds like a unlike metals in contact with each other. THis will cause galvanic corrosion (very similar to electrolysis) and that will eat up metal if not controlled. The only way to fix this issue is to get rid of the two different types of metal. Personally, it sounds like that one motor was not built correctly and had the wrong parts installed. The parts in question would more than likely have been near the point of the corrosion. So, it is possible (for example), that a brass head gasket was installed to a steel block. This could cause what you saw. But, it would have been very obvious what was wrong. As a general rule, if the metals are of different colors, galvanic corrosion is a high possibility. Even keeping the metal colors the same, is not a prevent all. Knowing what metals are where and doing a little bit of research is advisable. Sticking say stainless steel with conventional steel is normally safe, aluminum with steel isn't too bad.

Hopefully this gives you an idea of what happened. As for whether your current motor will suffer the same thing, I am not sure. But, atleast you know what to look for. Maybe you can see part of the head gasket sticking out and you can do the idiot check.

 

Thanks Chris!

...Maybe it would be helpful to fit a "sacrificial anode" out of zinc somewhere in the cooling system....?

 

Electrolysis is very different than galvanic action. Unless there was a source of stray DC current feeding into your engine, the problems were caused by galvanic action.

A properly maintained coolant system (ie fresh coolant and OEM components) will outlast the rest of the car. No need for gimmicky snake-oil anodes, sacrificial or otherwise.

 

There is no coolant anywhere near the intake manifolds on a V12. Worst case would be corroded cylinder heads at the block mating face, but I don't recall ever seeing a significant amount on an HE head, just earlier.

 

Mikey, galvanic and electrolysis are actually pretty close in nature. The big difference is how the current is produced in the two. In electrolysis, the current is supplied by an outside source and then through a conductive liquid, the interaction between the metals occurs. Where in galvanic corrosion, you have 2 dissimilar metals that in the presence of a salt (suspended in a liquid), they form a voltage difference between the two metals. Since the metals are in contact with each other, a current flows, again resulting in corrosion.

 

I think we're violently agreeing in every detail except that I consider the differences you noted between electrolysis and galvanic action to be fundamental due to the requirement for an outside source of current in electrolysis.

It is quite relevant in my 'other' car hobby and ongoing concern for the pocket book when aluminum radiators and coolant expansion tanks get eaten away within months due to an improper alternator path to ground.

Cheers!

 

Then I guess the mechanics were BSing me? What else could have caused this symptom...blown head gasket?

Hmm...I think he showed me a hole near one of the intake valve guides, but this was so long ago I cannot fully remember.

I distinctly recall them saying it was "electrolysis" but that doesn't really mean anything...hence my concern about disconnecting the battery. I had theorized that stray current had been flowing through the coolant as an electrolyte over an extended storage period.

Oh and I was kidding about the sacrificial anode. Those are used on MY other hobby...performance outboards.