Hi...what did the mechanic say about the leak you found? That appears to be a trans cooling line.....
Did your car overheat just the one time?

 

It happened twice in about 10 minutes...but after I put coolant in it, it was fine. But then I found that leak the next day and now he can't get it to do it again...frustrating.

 

What exactly was the alarm's OBDII code?
Did the CHECK ENGINE light illuminate too?

What does the leaking fluid feel like?
Slippery and/or thick like fluid?
Or not slippery like coolant/water?
Touch a white paper towel to it: what color?

Do these in sequence together same time, AFTER HAVING DRIVEN CAR EARLIER SAME DAY. Not first start in early morning dampness: drive it until warm then let the entire vehicle go cold.
1. Cold, pull motor oil dipstick looking at color and clarity: is it clear/golden or milky?
2. Shine a light into the cold tailpipe, look and feel for any wetness.
3. Get help: at cold start-up dangle a clean white sheet of paper about 6" from exhaust tail pipe, start motor normally no revving and hold paper for a full minute and check for moisture splatter.
4. Drive vehicle a few miles, then park and leave motor idling and repeat #3 with fresh sheet of paper if needed.
5. Get help: raise rpm above idle (with fresh sheet of paper if needed) for half a minute. No need to go crazy, normal around-town rpm is fine.
6. Raise hood, keep hands away, look for any active leaks using bright light. Is there a faint smell of something hot burning?

 

Thank you so much for your reply! I honestly don't recall if the check engine light came on...I was having a bit of a panic moment. LOL The information center in the dash just said something about it overheating and to "idle the engine." My oil isn't milky...I touched the leaking fluid, but honestly it was more gritty and dirty feeling than anything...and now it's not there so I can't inspect that again.

 

Those radiator tanks are known to hairline crack and hold pressure when cool only to leak when hot and under pressure. Chased this one around in mine for a while.

 

Thank you! Makes sense!

 

Thank you!

 

Same issue here but no leak 😐

 

Check reservoir make sure its full, follow up on post #3 and report back with what you find

 

2016 impala Ltz. Coolant goes down when I put it in but I don’t see any leaks

 

Welcome. Have you looked into the suggestions throughout this thread yet?