Adding a proper breather kit is an easy and great way to prevent water from entering into differentials and the transmission when driving through deep water. The kit also includes filters to prevent dirt and debris from entering into the respective components. The original breathers have no filtration.
I purchased a Universal 4 Port Breather Kit for about $30. This is perfect for the 4 major components:
-Front Differential
-Rear Differential
-Transmission
-Transfer Case
Tools & Parts:
- 4 Port Breather Kit
- 3/8″ ID Fuel Line
- 1/4″ ID Fuel Line
- Hose Clamps
- Pliers
- Zip-ties (if not supplied with kit)
- 10mm Wrench
- 3/8 hose to 1/8″ NPT adapter (stainless steel)
- 5/16 hose to 1/8″ NPT adapter (stainless steel)
- Automotive Thread Sealant
- RTV
Front Differential
The front differential is the most problematic. It is the lowest breather in the system and only has a small metal cap, not great for preventing water from entering if the differential housing is submerged.
Note: We did this install while replacing the radiator. This makes access easier, but it can still be done with the radiator in place.
1. Adapting this cap style breather to work with the breather kit is simple. First the cap must be removed. This can be done with a pare of pliers. The cap is floating and lightly crimped on to that breather port. Just pull it off gently.
2. The nylon breather port is now exposed. It is a male hose barb like feature of 10mm (3/8″) diameter. This is extremely convenient, as a hose with matching ID (3/8″) can be clamped on. Using fuel line or NBR hose is recommended, since gear oil is petroleum based. Using heater hose or non-fuel rated line could result in premature hose failure.
A stainless steel crimp style hose clamp was used to attache the 3/8″ ID hose to the breather port. Take care when crimping or tightening hose clamps, as the breather fitting is made of nylon.
3. Next, the 3/8″ hose needs to be adapted to the pneumatic fittings supplied with the kit. The pneumatic fittings are technically 1/8″ non-tapered BSP (28 TPI), not 1/8″ tapered NPT (27 TPI). BSP size adapters are harder to find hardware for, but for this application, which has no pressure, the two threads are close enough. Thread sealant was added in addition to the included o-ring to ensure we get a good seal.
4. Install the adapter fitting on the breather line and run the pneumatic tubing to your breather location. I was able to re-use the existing brake and fuel line clips. It is important to keep the tubing sloping upward from the differential. Thesis eliminates low spots known as traps. If oil or water enters the breather tubing it will get stuck at the low spot and the breather will not function as well.
5. Alternatively, you can remove the plastic breather and rubber seal entirely and weld in a proper hose barb. We did this later on when replacing our differential.
Rear Differential
Transmission & Transfer-Case
The automatic transmission and transfer-case breather system is connected from the factory. The transmission breathes into the transfer-case, and then the transfer-case has a breather plug. I am not sure why Mitstubishi choose to do this as the fluids in the transmission and transfer case are different an this could lead to some cross contamination.
1. To work with our breather kit the hose between the transmission and transfer-case was simply cut and adapted to the supplied tubing. There is now one line for the transmission and one line for the transfer-case. Having individual breather lines eliminates the possibility of fluid cross contamination
2. The OE breather cap was simply filled with RTV and replaced. The OE location is now sealed.
Rear Differential
Unlike the front differential, the rear has a proper breather hose. It is just a matter of tying this hose into the breather kit.
1. The rear breather line was dry rot, and a little too short to keep with our lift. A new silicone line used with the fittings:
2. The SS hose fitting was welded to some bar stock to create a bulk head style mount.
3. Everything was tied together. I used a left over P-clip to move the breather hose inboard.
Breather Filter
The breather filter assembly was mounted in the air filter compartment:
1. route the hoses from the breather kit to their various components:
