How to Replace a Transmission Hose Going Into the Radiator

by Gary Proulx
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young red-haired woman with her broken car. image by ta_samaya from

The hoses traveling from the transmission to the radiator are called transmission cooler lines. They channel hot transmission fluid to the radiator, where it is cooled, then return it back to the transmission. They typically resemble brake lines and are made of metal. Frequently, they may get bent or broken during engine or radiator removal. Older vehicles often have these lines patched with rubber fuel lines. When the line is broken or kinked, the entire line should be replaced.

Step 1

Raise the vehicle with a jack and set it on jack stands.

Step 2

Locate the transmission cooler line fitting at the back of the radiator and remove it by turning it counterclockwise. Have a rag ready as transmission fluid will seep out.

Step 3

Follow the line back to its insertion point in the transmission. With the appropriate sized wrench, unscrew the fitting from the transmission by turning it counterclockwise. Catch any leaking fluid with the rag. If there are any frame clamps holding the line, loosen them then slip the line under them.

Step 4

Compare the old line to the new one. Lay them both on the floor and be certain that they are identical. Make any bends or adjustments before putting the line in place.

Step 5

Place the new line into position, being careful not to bend or kink it. Tighten the fittings on both ends by turning them clockwise. Verify that the new line follows the path of the old one. Reconnect any frame clamps holding the line in place if necessary.

Step 6

Lower the vehicle from the jack stands with the jack then start the engine. Check for any leaks. Check the transmission fluid level and add fluid if necessary. Always use the type of transmission fluid recommended in the owner's manual.

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