Transmission Line Replacement -

Transmission Line Replacement

Transmission fluid likes to be at a constant temperature. If it is too hot or too cold for too long, the performance can fluctuate and potentially cause damage to the transmission.

0-istock_33002370_xxlargeTransmission fluid likes to be at a constant temperature. If it is too hot or too cold for too long, the performance can fluctuate and potentially cause damage to the transmission.

If the fluid is at a constant temperature, it behaves in a consistent manner in terms of its friction and lubrication properties. What can help control the temperature is the transmission cooling circuit.

The path of the fluid in the transmission lines is not as much about the destination as the journey. The size and length of the transmission lines, along with the size of the cooler, controls the temperature of the fluid. Also, the size of the engine and weight of the vehicle can determine the design of the transmission fluid cooling circuit.

Another thing to consider is how a modified transmission with a larger transmission cooling circuit might do more damage than good. On modern vehicles, the cooling circuit is designed to manage the fluid temperatures during startup. If the fluid can’t warm up quickly due to the increased volume, damage to the transmission friction surfaces can occur. The same goes for a bypassed cooling circuit. Why? Because fluid that is too hot can damage friction surfaces.

0-x05ar-ch010Replacement

With the complexities of today’s vehicles, it is always recommended that you replace a transmission oil cooler line with one that matched the original design. Patching or cobbling together a replacement line with a hose can change the thermodynamics of the cooling circuit.

While ATF was designed to operate at temperatures of 175°F, the reality is that transmission and cooling lines are routinely subjected to conditions that cause it to operate at 220° F or more, and up to 300° F intermittently. Essentially, as the heat goes up, assembly life goes down.

Transmission cooler lines are also subjected to high pressure. On older vehicles, 75 to 150 psi is standard. Surges up to 300 psi can be seen on newer electronically controlled transmissions. A small leak under these pressures can lead to serious problems.

It is recommended to always replace fittings when changing a line. If the opportunity to change fittings does not exist, you should make sure you can install new clips, O-rings and washers.

Engine cavitations, road vibration and reduced underhood space can have an effect on your hydraulic hoses.

0-x07st_ot030-copyFlushing Lines

If a transmission has failed catastrophically and the vehicle has high miles, it is a good idea to replace the cooler lines.

Cleaning out the cooler is essential for completing a line or transmission replacement. The cooler can hold a large volume of debris in the passages. If the transmission has “grenade,” it might be impossible to backflush all the debris from the cooler. If the transmission cooler is a standalone unit, replacing it might be a good investment to make sure the replacement transmission is not damaged. There are some machines that can backflush the cooler and lines, and some machines can pulse the cleaning fluid to help dislodge debris.

The future of the transmission cooling circuit is getting hot. On some new hybrid and diesel vehicles, the transmission fluid is heated with exhaust gasses. This can help heat the fluid, increase the efficiency of the transmission and reduce wear caused by start-up.

Article courtesy Brake & Front End.

You May Also Like

Ball Joint Inspection

It’s important to remember not to miss a worn joint. If a ball joint fails, the driver loses control of the vehicle.

Don’t miss a worn joint!

Detecting and measuring wear in a ball joint is critical to ensuring the safety of a vehicle. 

Types of Ball Joints

A ball joint is made up of a housing, ball stud, bearings, end cover and Belleville washer or spring. A Belleville washer is a conical-shaped spring designed to be loaded in the axial direction. The joint is attached to a control arm by pressing or riveting the joint into the arm. If the joint is pressed into the arm, it will require a special tool to remove the old joint and install the new one. 

Ignition System Do’s and Don’ts

Why do ignition systems give technicians problems when diagnosing ignition-related misfires? The answer is that some technicians use tests that might give inconclusive results or do damage to the coil or drivers inside a module.

BMW N54 Cooling System Problems

Let’s take a closer look at this water pump, how to replace it efficiently and what other components should be replaced along with it.

BMW Dual Clutch Transmissions

BMW uses a wet clutch with separate inboard and outboard sections for the two sub-transmissions.

Brake Pad Edge Codes – What Can They Tell You?

The “Edge Code” can tell you information about a brake pad’s friction material.

Other Posts

A Closer Look At Key Programming

When it comes to key programming, there are different levels of security access depending on the year, make and model of the vehicle.

Steering Angle Sensor Service

Ninety percent of the time when a steering angle sensor code is active, it means the sensor needs to be calibrated.

Belt Service For Hybrid and Stop/Start Systems

Knowing how to “force start” a hybrid vehicle can be helpful if you are trying to diagnose a noise problem that involves the accessory belt drive system.

Fuel Pumps and Cranking

Diagnosing the problem comes down to understanding what causes a loss of fuel pressure.