Extending the breathers of the Suzuki Jimny

Extending the breathers of the Suzuki Jimny

By Daniel
- Updated 7 years ago
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1 comment

Simple modification that increases the under-water capabilities of the Suzuki Jimny.

The Suzuki Jinmny is a very robust and well built car for off-road purposes. If you have plans to go a little deeper than the standard factory wading depth limits you should consider this inexpensive modification to prevent water from getting inside the gear wheels.

The differentials and the transfer case box from the Suzuki Jimny have breathers fitted with a one-way valve inside the cap. This valve made of a coil spring and a rubber disk has the purpose to relief the internal pressure from the heated box blocking the entrance of dirt and water. The gearbox has it's own factory installed breather extension without any valves on it.

When crossing a deep river (water lever higher than the half of the wheel) there is the risk of water and solids get inside the differentials contaminating the oil, accelerating the oxidation process and the wear of the gears and bearings. There are many theories for the water entrance, some claim that the valve is so efficient that when the differential is quickly cooled it generates an intense vacuum that sucks the water thru the rubber seals. Others believe that the combination of the rubber disk and the tiny coil spring can't provide enough sealing in the presence of mud or other solids.

This article shows how to extend the original breathers from the wheel level to the engine compartment level using materials found in most of the DIY shops. This measure costs about 20 USD (if installed correctly), takes about 2 hours of your time and can avoid very expensive repairs.

Although I particularly never had problems with water inside the gears of my brand new Jimny I decided to extend the breather as a preventive action. With the caps/valves I took out from the differentials I did some experiences that drove to the conclusion they are very efficient when new.

NOTE 1: Sorry about the muddy parts. The Jimny had just completed a trail before I took the pictures. It's normally cleaner that that.

NOTE 2: It is impossible to get the oil sucked from a differential to the other or from the differential to the transfer case using a single line of breather extensions.

Materials and tools

  • Big pliers.
  • Screwdriver.
  • Piece of cloth for cleaning up the breather nipples.
  • 6 meters of reinforced rubber hose (300psi rated). Internal diameter of 1/2 inch.
  • 0.5 meter of reinforced rubber hose (300psi rated). Internal diameter of 1/4 inch.
  • 1 meter of reinforced rubber hose (300psi rated). Internal diameter of 3/8 inch.
  • Steel clamp for 1/2 inch hose.
  • 3 "T" hose adapters with 1/2".
  • 140mm length plastic lock straps .
  • 1/2" to 3/8" hose reduction adapter *.
  • 1/2" to 1/4" hose reduction adapter **.

* The 1/2" to 3/8" hose reduction adapter is not easy to find in some markets. Alternatively you can use 10mm external diameter pipe to fit both hoses.

** It is possible to fit the 1/4" hose inside the 1/2" hose. If you need lubrication use soap or glycerin since they don't attack the rubber.

Preventive maintenance

  • Every time you replace the engine oil or lift the car, verify the clamps and possible damages to the hoses. Remember that without the check valves the whole system can be compromised in case of failure of one the pipes.
  • To check if the hoses are properly connected and there are no leakages you can blow the end of the breather extension line. If the pressure increases everything is OK.

Step by step of the installation

Breather materials
Materials needed. 300psi reinforced hoses for water or air (1/2", 3/8" e 1/4"), "T" hose adapter, hose clamps, intermediary connecting pipe and locking straps.


Valve removal breather.
Carefully remove the caps (check valves) from the differential breathers. The cap holds directly to the nipple and requires pliers to be removed. Note that is not recommended to reinstall the caps once they were removed.


Rear breather installation
Start the installation from the rear diff to the front of the car. Clean the breather nipple before fitting the 1/2" hose. The differential moves so don't stretch the hose. From the rear differential follow over the top of the fuel tank. Avoid twisting the hose and the contact with the exhaust pipe.


Transfer case breathers.
The next step is the transfer case. It has two breathers.


Smaller breather connection.
For the smaller breather you can fit the original hose inside the 1/4" hose and then the 1/4" inside the 1/2 inch. There are many other ways to do that. Don't let any of the hoses to get in contact with the axles.


Smaller breather without the cap
The second transfer case breather is much more complicated to fit. It has a smaller nipple (about 4mm) and It's difficult to reach.


Larger breather after installation
Use the 3/8" and double check if the connection is tight enough.


Installation in the front differential
Placing the extension in the front differential is analog to the rear diff. For this one you should keep the hose away from the axle, the suspension spring and from the radiator line.


Holding the hoses
The best path for the hose is to follow the brake oil lines but don't use the pipes to hold the extension hose in place.


Hose split
Hose split for the front differential and the engine bay breather. Notice that no clamps were used, if something drags the line out we want it to be disconnected from here and not from the nipples that would expose the inner parts of the cases.


Final siphon
Final assembly on the engine compartment. The "siphon" curve offers extra protection in case of flooding. A piece of cloth at the end is enough to prevent the entrance of bugs or dust. Leave some extra centimeters of hose so you can blow inside to check for leakages.



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