Yes the vents can easily plug with undercoat and dirt etc . If in areas of road salt during winter the cap on the vent rusts and plugs. The resulting pressure forces the diff fluid past the seals creating leaks. Have 40 years in the trade and a common problem but overlooked as a root cause of leaks. My 2013 journey with 108,000 km is leaking, plus started the left hand turn grinding and often a wheel drag as well, either left front or rear starting from a stop with wheels slightly turned to the left. A new Viscous coulper is $2500 plus tax in Canada. So purchased a used unit with 6 month warranty, will replace the diff vent ( very difficult to get at , a push in fit ) drain and fill the diff and this rig will be traded. Plus no heat on passenger side due to the interior heat door not working in the heater housing. Another habit of journeys, this one has the shaft broken on the inside of the heater box. Estimate from dealer to repair is $2200.00 .
