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Hey Engine Man: Does Electrolysis Affect Gas Engines, As Well?

Successful Farming Engine Man Ray Bohacz has engine grease and field dirt under his fingernails from a life spent repairing vehicles and running a farm. When he’s not busy in the shop, he's working on maintenance articles and videos for Successful Farming magazine and answering questions from readers. The following is a letter the Engine Man received from Bruce Whitaker:

Thank you very much for addressing the serious issue of electrolysis in Successful Farming magazine. I grew up on a farm and still maintain my dad’s equipment, along with owning my own heavy-duty trucks. In all my years of wrench-twisting, I never had anyone mention the electrolysis test you described in your article.

I always relied on coolant additive to control this issue along with other tests performed during preventative maintenance. The test you shared is one that takes the guessing and insecurity of not being certain about this silent killer completely out of all equations!

I am curious why it seems diesel engines are more subject to electrolysis over gasoline engines? Is it simply that gasoline engines are better grounded in most cases?
 

Response from the Engine Man:

Though the main focus of that article was directed at diesel engines, know that electrolysis from a poor ground can happen to any engine. There are many gas engines that suffer repeated pinholes in the heater core, radiator, or aluminum intake manifold due to a poor ground. Depending on where the high impedance ground is found, a diesel is usually more prone to electrolysis due to the following that has nothing to do with the fuel it uses:

  1. Higher amperage starter motor load vs. a gas engine. More current flow means the ground is taxed at a higher rate.
  2. Extended running time and use vs. most gas engines.
  3. Wet liner design in most applications.
  4. A higher rate of aftermarket or upfitter equipment that, when installed, may not be grounded properly.

In contrast, due to the lack of aluminum in many heavy-duty diesel engines, in some ways, they are actually less impacted by electrolysis from a poor ground.

The coolant’s ability to be a conductor of electricity comes into play, too. Please note, the major reason supplemental coolant additives (SCA) are used within the radiator of a diesel engine is due to the nature of the wet cylinder liner to vibrate and create air bubbles in the coolant. These bubbles then attack the cylinder liner and eventually eat it away and ruin the engine. This is known as cavitation erosion (CE). The hallmark of CE is a series of pinholes and degradation of the liner in a straight row (top to bottom) and on the thrust side of the bore. The bad thing is,  electrolysis can also eat a cylinder liner in a like fashion as CE.

Electrolysis at the cylinder liner is usually more random in its spacing and not dedicated to the thrust side of the bore. For this reason, use the voltage test as a preventative maintenance test on all engines. If there is a problem, you can determine if it was caused due to a bad ground or from depleted or poor-quality coolant SCA and catch it before it is a major expense. 

Interestingly enough, many heavy-duty trucks, when not having a good chassis-to-engine ground, are damaged by electrolysis due to the static charge built up from the tires rolling on the pavement.

Do you have a maintenance question? Email Ray Bohacz at  SFEngineman@agriculture.com .​

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