Antifreeze Leak

My 2001 Durango has a 5.9 V8 and I have a antifreeze leak. I took it to my mechanic and he says that he actually can't see where the leak is coming from so he will have to split the engine and transmisson to get a better look. But he thinks it's coming from what they call a "Blow out plug"? He says it's an alumunum plug that's driven into the engine and is designed to blow out if your antifreeze mixture has too much water and starts to freeze then the plug will give way to allow for expansion so it doesn't damage your engine block. Any way to make a long story short has anyone else experienced this, and if so is there an easier way to fix it. I have also tried various stop leaks and nothing. So I'm open for suggestions.

Do you smell antifreeze when you are driving? I had a similar problem and it turned out to be my heater core. You could not see where it was leaking only smell antifreeze when the heater was on. This is quite a job to do just so you know as you will have to pull the dash if the heater core is bad.

I found that there is a tube that runs through the firewall from where the heater core is located. The tube is located on the firewall just behind the transmission dipstick. If you look you will see it. I would suggest sticking your finger in that tube and seeing if you can feel any antifreeze, if you do your heater core is toast. If you can't get your finger in there try something else like string or something that will come in contact and soak up the antifreeze so you can verify.

This is not documented anywhere that I can find, only discovered it after I replaced my heater core.

By the way the mechanic I took it to could not find the leak either, but thought it might be the heater core.

Hey thanks for the tip I'll try it. So were you getting puddles of antifreeze under your vehicle before you changed the heater core. And yes after you drive the vehicle you do smell a strong antifreeze oder especially if its been driven for a long period of time. Also after he changed the heater core did the problem go away?