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Prevent Premature Engine Failure by Testing for Electrolysis

Engine electrolysis is one of those issues that can grow to become a major problem if ignored.

The term describes electrical current on the ground side of a circuit passing through the engine coolant as a conduit. This is due to a poor ground connection somewhere on the machine or vehicle.

When electrolysis is evoked, there is no way to predict where the final ground path will be.

Eventually you will be able to see where the ground path is since electrolysis attacks and destroys the surface it uses for a ground. It is responsible for mysteriously pitted cylinder liners, destroyed radiators and heater cores, abnormal water pump or head gasket failures, and diesel injector cup degradation, among other problems. 

The hallmark is extreme pitting or pinholes that can often be found in aluminum manifolds and radiator tanks or cores (copper or brass also). Electrical current also uses coolant as a ground path. This destroys the nitrate in the antifreeze and enables the production of ammonia. The ammonia attacks and degrades any copper component in the cooling system.

This failure caused by electrolysis produces different results, and it degrades the copper rather that producing the common pinholes. 

Supplemental coolant additives (SCA) can replenish the nitrates, and that will arrest the production of ammonia. Additives won’t stop the electrolysis. In severe cases, an engine can be destroyed in as little as 30 days of use. 

The method of testing for electrolysis is to employ a volt-ohm meter test using a voltmeter (DC scale). Place the positive lead of the meter in the engine coolant without touching the radiator sides. Clamp the negative lead on the battery ground.

For the test to be valid, there needs to be an electrical load. To get that load, first disable the engine so it does not start. (Either pull the wire off the fuel solenoid on the injection pump or ground the coil wire.)

Crank the engine over while reading the voltage in the coolant.

Next, start the engine and retest loading individual electrical circuits by turning off the lights, heater, air conditioning, etc.

With a cast-iron engine, the reading should be no more than 0.3 (3∕10) volt. A reading of 0.5 volts will destroy a cast-iron engine over time, and 0.15 volts will damage any aluminum component or engine.

If voltage is discovered, shut off one electrical load at a time until the reading drops to zero. Then, identify and fix the ground path and change the engine coolant.

An electrolysis test should be part of a preventive maintenance schedule since it is very easy to perform. 


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