If you’re operating equipment in wet weather, especially at full highway speeds, it’s possible that water is finding its way into your air intake system. If not addressed, water can lead to costly problems both on and off-road.
What can you expect when moisture gets into the air intake?
- Some or all of the filter media may get saturated
- Air intake restriction readings increase, indicating a blocked air filter
- Dust on the filter and in the housing will turn to mud and set hard when dried
- Vacuator valves will block
- Ongoing exposure may cause the filter media to weaken and break down
- The intake system could corrode
- Extreme quantities of water can cause catastrophic engine failures
Luckily, there are simple, practical ways to minimise the ingress of moisture.
Common water prevention intake accessories: air ram, rain cap, inline separator, and in-line moisture skimmer
Moisture Control Solutions
For On-Highway Equipment
The first line of defence can be an appropriately sized forward facing air ram, installed correctly on the vertical intake pipe. Air rams provide the added benefit of forcing air into the intake and at highway speeds, reducing the overall intake restriction.
Rain Caps or are used on housings not suited to air rams. These are effective at minimising moisture while adding little additional restriction.
Horizontal and Vertical Inline Separators: Always installed before the air cleaner assembly. While separators do not provide the efficiency of dust and water removal you expect from a Donaldson off-road air cleaner assembly, they are extremely valuable on highway-style trucks subject to adverse conditions.
Inline moisture skimmers: Designed for horizontal installation before the air cleaner assembly, moisture skimmers can be a simple installation that replaces an existing hump hose.
These options:
- Have no moving parts
- Are virtually maintenance-free
- Generally require occasional inspection during routine service works
By reducing water in the air intake, you can expect longer filter life, lower maintenance costs, and improved engine performance.
For Off-Road Equipment
Except for air rams, the above solutions, including stack-top moisture eliminators, can be applied to many off-road, stationary or slow-moving applications.
Commonly, off-road equipment is delivered with a type of pre-cleaner to separate coarse dust before it enters the air cleaner assembly. Water droplets behave like dust and are readily separated by functioning pre-cleaners.
Heavy-duty off-road SSG and SRG housings have optional rain shields to prevent moisture from saturating dust-loaded pre-cleaning tubes. Water and dust will always make mud that dries, blocking tubes and dramatically reducing air filter service life.
Remember
Leaks before the air cleaner can allow water to be drawn in, saturating air filters.
Leaks after the air cleaner will allow water and dust into your engine, leading to serious and expensive damage.
The Bottom Line
Moisture in your air intake system isn’t just annoying — it’s a genuine threat to engine health. With the right tools and a few simple checks, you can minimise water intrusion, protecting your equipment and saving maintenance costs.
