Dealing with diesel bug in Mindelo
When the wind completely died off 5 days into our crossing to Cape Verde, and we had tried every possible sail combination to at least stabilize the boat in the swell, we reluctantly turned the engine on.
A day later, we started hearing our engine loose power inexplicably. We looked at all possible causes for our troubles, changed the fuel filters (a couple of times) and limped our way to Mindelo marina.
We had three suspicions: Diesel bug, clogging in the pipes or the injector, or broken diaphragm.
Diesel bug is a common name for a few different types of bacteria, algae or fungus, that can grow in between the layer of diesel and water that can appear in the fuel tank.
Diesel bug reproduces VERY rapidly in the tank and creates slime or crud in the fuel, which eventually clogs the fuel pipes in the engine, starves the engine from diesel and prevents it from functioning.
Every time we fueled up, we would pour some additive in our tanks to prevent it, and would try to keep our tank as full as possible to avoid a buildup of condensation in our tanks, which in turn would create a layer of water the bottom of our diesel, in which diesel bug could develop.
Our first instinct when the engine lost power was to look at our diesel tank to check the state of our fuel and change the filters. Everything seemed to look alright, and we broadened our troubleshooting to issues of a more mechanical nature.
The diesel bug ranked the lowest on our suspicion list when we arrived in Mindelo Marina.
But taking the little pipe that sucks the diesel from our tank into the engine left very little doubt: against all our precautions, we had caught the diesel bug! 🥴
A thick layer of slimy crud had developed at the end of it, and there was no wonder why our engine was losing power. At that moment, we even felt lucky that we could operate the engine for small periods of time at low revs, which allowed us to dock Polar Seal at the marina upon arrival. The bug could have completely clogged a pipe and prevent the engine from functioning at all.
Getting rid of the diesel bug involves:
- Sucking all the diesel out of the tank.
- Removing the tank out of the boat (which itself involves tearing the boat apart)
- Cleaning the diesel tank
- Putting the diesel tank back in.
- Getting new diesel and try to not get the diesel bug again!
Mindelo marina turns out to be a great place to deal with diesel bug. We immediately found very skilled mechanicians to help us troubleshoot and deal with the issue. They came early, were very professional, let us do what we could do ourselves and lent us a hand when we needed it. They took our diesel tank away and cleaned it off-site, to re-deliver it early in the morning a day later.
We are putting the tank back in the boat as we speak, and will hopefully get our boat back by the end of the day!