All transmissions have a vent to maintain equal barometric pressure inside of the transmission. If the vehicle is driven through water (as in a flood) and the water level is at or above the vent, the water will cool the unit lowering the internal temperature and water is drawn inside of the transmission.

This hose is a vent hose for the transmission and would not be connected to anything. The vent is used by the transmission so it will not build up internal pressure and push oil out of any seals.

Car transmission lines connect your vehicle’s transmission to the vehicle’s radiator. Also known as transmission cooling lines, they are typically made of metal or composite aluminium and rubber hoses because they can handle the flow of hot transmission fluid.

Transmission Breather Evaluation 2019-26-0339 Breather assembly is mounted on transmission to maintain the pressure equilibrium inside transmission. Breather allows the transmission to breathe air when the air inside transmission expands or contracts due to heating and cooling of lubricating oil during vehicle running.

In conventional automatic transmissions, air flows into and out of the transmission housing through a vent or a breather tube during transmission operation. The in and out flow of air can be characterized as transmission breathing. This requires the transmission operating fluid be changed periodically.

A breather is an essential component of a gearbox. Oil loss from the reducer can increase heat generation, lead to more wear of internal components, and ultimately gearbox failure. A typical breather prevents this pressure from building by allowing hot air to escape and fresh, cooler air to come in.

A breather plug is a device that allows the gearbox to breathe, thus equalizing internal and external pressure (Air inside the reducer expands during operation and contracts when not in operation).

As the air in your diff housings heats up, it expands, and pressurises the diff. The breather lets it release this pressure out into the atmosphere, instead of out via your axle seals.

Why are Diff Breathers important? Extended diff breathers are extremely important insurance for your 4WD if you drive through water. By fitting diff breathers, when your diff gets dunked in water it will contract, and suck air in through the breather (as a pose to water through the seals!).

one way is to drain fluid with the fill port closed (crack open the fill first just in cast it is suck then close ti again) if the fluid comes out “goes glug glug glug….” as it alternately flows oil out then air back in then the breather still has the OEM evil little flapper or is otherwise plugged, if it pours out …

• The Harrop universal breather kit is a simple installation for a variety of different vehicles.
• First mount the breather block manifold to the firewall or inner front guard in the engine bay using the self-drilling screws supplied.

all diffs , transfer cases/gearbox’s have factory breathers as far as I know, problem is they are usually positioned too low and get covered with water during crossings, or they get clogged up with mud and don’t “breath” anymore causing any seal to suck in water or blow out oil.

ARB Diff Breather Kit A diff breather kit stops your differentials (as well as gearbox and transfer case) from sucking in water when driving through river crossings and large water hazards, leading to serious and expensive repairs.

A differential / axle breather serves the important purpose on a 4WD vehicle of venting the air pressure in drivetrain assemblies such as the differentials, transmission and transfer case.

A clogged breather can absolutely cause a failed axle seal. As the differential heats up, there is a build-up of pressure and the pressure needs to go somewhere. If the breather isn’t working, the pressure will find the path of least resistance and that’s the oil seals on either ends of the axle housing.

It’s set to open at 0.7 psi (4.8 kPa). However, this vent doesn’t allow air back in during cooldown, to prevent water intrusion. As the air cools down, it can pull a vacuum of between 3 and 5 psi (20-34 kPa).

All gearboxes in your car must be vented to the atmosphere. This includes transmissions, transfer cases, and axles. The primary function of the vent system is to make certain that the axle housing is never exposed to vacuum or pressurization.