In the Successful Farming magazine, engineer Ray Bohacz responds to the question 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?
Electrolysis from a poor ground can happen to any engine. There are many, many gas engines that suffer repeated pinholes in the heater core, radiator, or aluminium 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:
1. Higher amperage starter motor load. More current flow means the ground is taxed at a higher rate.

2. Extended running time at high working loads.

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 aluminium 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 a supplemental coolant additive (SCA) is used with a diesel 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, and electrolysis can also eat a cylinder liner in a similar fashion. 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 PM on all engines. If there is a problem, you can determine if it was caused due to a bad ground or due to depleted or poor-quality coolant SCA and catch it before it’s a major expense.