On the Iveco Daily 4×4 the axels and transfer gearbox are fitted with non-return valves which allow gas out but not in.  However, having had both axels and transfer gearbox oil seals replaced due to oil leaks, I have lost confidence in this breather system.  I have therefore installed an ‘ARB Differential Breather Kit’.  The ARB kit allows you to join all the breather pipes into a common manifold fitted with an air filter.  The advantage of this axle breathers and gearbox breathers system is that it allows air in and out of the ‘sealed’ axels and gearboxes.

When the axels and gearboxes heat up, the air inside gets hot and expands; the hot air is then allowed to escape through the breathers.  If the axel or gearbox gets cold (when you park up or drive through a river) the air is cooled and contracts, thereby lowering the pressure in the axel or gearbox.  As the standard breathers are fitted with non-return valves, air cannot enter the ‘sealed’ axel or transfer gearbox.  Therefore the lower pressure in the sealed axel or gearbox, tries to draw in air or water (if in a river) past the oil seals as the valve on the breather will not let in air.  However with the ARB kit, clean air is drawn in through the air filter and there is no danger of air or water being drawn past the oil seals.

The Axle Breathers

I found that the original valve on the end of the axel breather pipes could be replaced with a 1/8” BSP to 8 mm push fitting. This allowed the ARB supplied 8 mm breather pipes to be connected to the existing breather pipes.  When I removed the rear axle breather valve I found it had rusted badly and was very close to being blocked!  For the transfer gearbox I used a 90 degree M20 to 8 mm push fitting to connect the ARB breather pipe.

 

 

 

 

 

 

 

The main gearbox is already fitted with a breather pipe that is routed up behind the engine to the top of the engine compartment.  This breather was also fitted with a free flow (not a non-return valve) air filter, so I did not connect this to the ARB manifold.

I mounted the ARB manifold behind the left wheel arch liner, near the ABS unit.  This was a convenient location for all the pipes to route to, but was not high enough should I encounter deep water.  The air filter has to be kept above the water, so I installed a 90 degree ¼” NPT to 8 mm push fitting in the place of the air filter on the ARB manifold.  I then used an 8 mm pipe to connect the air filter to the manifold.  This meant that I could mount the breather air filter high in the engine compartment.

 

 

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