I grabbed a new to me cooler line from the junkyard which appeared to be in perfect shape (after my engine fan exploded killing mine.) Twice now it has popped off with the engine running and made a huge mess and dumped all my oil out.
The last time I put it on I pushed hard and felt and heard it click. I drove it for my long test drive of about 20 minutes, and about 2 minutes before I made it back home the oil light came on and I shut it off and coasted to a stop.

This time around I made extra special sure the hard line (male) was perfect and clean, and I made sure the clamp works on the female and cleaned it up. I pushed it on until it clicked, I visually watched the black plastic circle move forward. I pushed the line in and out as hard as was prudent a number of times. Pulled very hard and wiggled and it wouldn't budge. I ran it 30 minutes in the garage and it doesn't leak and is still tight.

Is there anything else I need to do or look for?? I obviously can't have this keep happening.

 

Make sure the plastic release is all the way forward after installing.

 

This happened to my wife after replacing the radiator on our Disco, with the ATF one, and left her stranded in a target parking lot. I swore I clicked them on all the way when I reinstalled them, but alas...was wrong...there's like a false click and then the REAL click. That's when they're actually on.