wyattearp29

So I put a new tranny line on last week. This the line to the heat exchanger from the tranny. Everything was good for a few days. After i get home from work last night I notice it leaking again. What would cause it to crack again. It has only been on for a week. Could my tranny and motor be flexing.

j-fox

Vibration!!!

cdennyb

ABSOLUTELY, what he said. In order to prevent unwanted flex and fatigue cracking of steel lines it is necessary to clamp them within a few inches of the port so that any flex is absorbed by the longer upstream area of the tubing. What's probably happening is the flex is being concentrated at the flare and causing the failure. Try to find a good tight line clamp and spot to put it as close to the port as you can, usually within 6-8". That will no doubt eliminate your issues. Take a look at the lines up front, for the A/C, for the oil cooler, etc. and try to duplicate what they did there as far as clamps go. Also under the truck near the main fram rails you can see how they clamped the fuel lines coming from the tank.
Remember they spent a BIG sack of money researching and designing those clamps to eliminate failures. Extra parts are costly and less parts are failure prone. Just a financial thing as far as the truck company is concerned. They clamp as little as they can to achieve the required stability without spending any more money than they have to on the vehicle.

wyattearp29

Yea I understand about clamping but why know. There was never a stock clamp on there. Maybe it is from the added pressure from the aftermarket valve body. Dave goerend says they make an updated line with a a piece of hose in between to take the shock out of the tube.

wyattearp29

So I ended up just putting on some barb fittings with some hose. So far so good. The fiitting going into the transmission does have a tapered thread. I thought in all the posts I read , they were both straight.