Diesel Control

Fernando DeMoura
October 2017

I can’t say I’ve ever been in a hurricane but as far as flooding I’ll say I’ve seen my fair share. The lakeside community I lived in as a kid was used to dealing with flooding. When the waves of lake Saint Clair started coming over the sea wall it was time to start laying sandbags. At night, I’d fall asleep to the sound of a dozen trash pumps running wide-open all around the neighborhood keeping the water level in check. As I write this article the news continues their coverage of Hurricane Irma and the flooding from Hurricane Harvey. I’m no civil engineer but it doesn’t look like that kind of flooding can be mitigated with sandbags. One video shown repeatedly by my local news broadcast was showing someone driving a 379 through flooded sections of Houston. He had water above his frame rails but his external air cleaners were still above the surface. Hopefully he had a 3406B or another mechanically governed engine because if he had a Series 60, or an electronic Cat then his ECM was underwater. Cummins mounts their Electronics up high on the block so I’ll give it to Cummins on this one. If I had to drive an electronic engine though 4 to 5 feet of water I’d pick the Cummins. Deeper than that Cummins ECMs are just as vulnerable to water intrusion as the rest when submerged.

This vulnerability is shared between Detroit, Cat, and Cummins because they all have a hole in the case known as a pressure equalization vent. This vent prevents the ECM case from blowing up like a balloon and pushing out its gaskets when heated or taken to high altitude. You don’t want to cover this vent. The only exception I can think of is if you were about to drive into enough water to submerge your ECM. These vents are designed to let air pass but block everything else but these vents can’t hold back much pressure and if the ECM is submerged odds are some water is going to get in. Just so I’m clear though, I strongly discourage operating your electronic engine submerged or partially submerged but if you had to in an emergency you would want to cover this vent on your ECM and even then, you are taking a risk. Many ECMs that are over 14 years old have a seal that’s deteriorated and isn’t keeping contaminants out anymore. Salt water conducts electricity, can bridge circuits, and transform the pins on a microprocessor control unit into green dust in minutes. Salt water can also bridge circuits not only inside your ECM but between sensor supply, return, and signal wires in your wiring harness especially if you have cracks in the wiring jacket. This could cause your timing sensor circuits to fowl up and stop reading RPM. That’ll stall the engine and result in a no start condition. Also make sure your fan clutch doesn’t engage. I’d hate to see what breaks first if that engages and bites into water. If your trucks wiring harness does get exposed to salt water I suggest washing off all the salt with fresh water then drying everything out with compressed air.

Fernando DeMoura

Diesel Control Service LLC.


Phone 412-327-9400