By now you’re probably aware that you should be carrying a portable air compressor like the Thumper or Thumper Max 12v air compressors that we sell here at 4WD Supacentre. Having the ability to re-inflate your tyres, an air mattress or even the kids’ footballs when you’re out in the bush is extremely handy, but that’s not where the usefulness of a 4wd air compressor ends. There’s a million and one uses for a portable air compressor when you’re 4WDing. Previously we’ve talked about how to clean and reseat a tyre back onto the wheel when you roll it off the rim, which is an excellent skill to have. This time around, let’s talk about another use for your air compressor, which is to help dry out a waterlogged engine bay after failed water crossing or bog hole.

Water and engines definitely don’t mix. That’s why we fit snorkels to our 4x4s, to let them breathe in air instead of sucking in water during deep water crossings. Even if you have a snorkel, there is still a way for water to cause havoc in an engine bay, and that is by getting into engine electrics. When water gets into wiring looms and plugs, it can create open circuits within the loom that can do anything from cause Check Engine Lights to come on, to completely stopping the engine altogether. So where does your 12v air compressor come into the picture?

The Thumper air compressor and Thumper Max air compressor both can rescue a waterlogged engine bay by letting you blow excess remaining water from all sorts of nooks and crannies. After a failed water crossing or bog hole where you’ve had to either winch yourself out or have someone winch you out, assuming the motor had a dunk under water, you need to act as fast as possible. That’s especially true if it was salt water or that horrible silty muddy water because if either of those are allowed to naturally dry, they leave behind salty, silty deposits that can cause all sorts of dramas. What’s even worse, is the cause of those dramas isn’t always immediately apparent, meaning that it may take hours and hours of diagnosis to find the root cause of the problem.

So how should you use your air compressor in your engine bay after a failed water crossing or bog hole? Once the vehicle is back on dry land, start by removing the air filter and checking for moisture in the air intake. If your snorkel did its job there should be no water in there and the filter element should not be damp. Ideally you should have a mate bring his vehicle up next to yours and leave it idling for you to connect your air compressor to. You can run an air compressor off a battery in an engine that isn’t running, but it’s much preferable to have the motor running to supply the 12v air compressor with plenty of power for maximum performance.

Hook up your air compressor and connect the hose so it’s blowing air. Start at the top of the motor on the driver’s side and methodically work your way across the top of the engine, blowing out any sort of water you can see that has pooled anywhere. Pay particular attention to electrical connections and plugs. Where possible, unplug each connection, give it a good blow out with the air compressor and then before you plug it back in, give it a hit with some water dispersant spray like WD40 or CRC. Plug it back in before you move onto the next plug, and only have one plug undone at a time. This will prevent any confusion as to which plug goes where if there are similar ones.

If it is a petrol-powered 4WD, pay close attention to the ignition system – any distributors, coils or high tension leads. It’s worth pulling each plug lead off – again, one at a time – and using your air compressor to blow out in the inside of the lead boot before fitting it back onto the spark plug. Once you’ve covered the top of the motor, check down each side of the engine for extra sensors that may need drying out.

Finally, use your air compressor to blow out as much water as possible from any fan belts or belt pulleys across the front of the motor and give anything a decent spray of water dispersant spray. This will give your motor a fighting chance of continuing to function normally even after an unexpected bath!