Transmission cooler lines on Diesels with Automatic Transmissions

Like many things on the diesel engine, the transmission cooler lines are subject to much vibration. The clamps that support them along each side of the engine pan have plastic inserts that prevent chaffing. Over time these plastic inserts break out and all you have left is a metal clamp rubbing against the aluminum tubing.

On a number of occasions I have seen these clamps wear right through the tubing thus depositing your transmission fluid on the road as you drive. Check your lines soon. A good preventative repair is to take the clamps off and cut 8 mm rubber fuel line to make new soft inserts. Reclamp the lines and you will not have to worry about them again.