Mysterious Coolant Leak

[hoe]

I've been chasing the mystery leak for years despite 2 new pumps. The resisvor will run low enough to trigger the light. Radiator is always full however.

I found my leak the other day as I seen it drip from the back firewall. The 2 metal hard lines that route to the rear heating. One of those lines drips coolant. There is no fitting to fix, need to change the lines itself.

Just another place for people to look. The lines bend under the body from firewall.

 

[smcnair]

I've been chasing the mystery leak for years despite 2 new pumps. The resisvor will run low enough to trigger the light. Radiator is always full however.

I found my leak the other day as I seen it drip from the back firewall. The 2 metal hard lines that route to the rear heating. One of those lines drips coolant. There is no fitting to fix, need to change the lines itself.

Just another place for people to look. The lines bend under the body from firewall.

those connectors suck to replace. Have fun with that.

 

[Chizzychase]

I would deffinetly start by looking into the water pump as mentioned before. My water pump developed a crack in it for no known reason I just noticed that it was dripping coolant everytime I parked it.

 

[oldchev]

Wish I had better news but this is what I have heard:
Its only the Castech 706 5.3/4.8 head that has issues. Not all 706's are made by Castech though so you have to pull the valve covers and check. Use this link below to a service bulletin on it.
http://ww2.justanswer.com/uploads/Bluegorilla/2008-12-05_142924_Coolant_loss_5.3.pdf

Sounds like you are not the only one if you have the 5.3 or 4.8 engine size in your vehicle.

 

[jacam7610]

those connectors suck to replace. Have fun with that.

I just changed the coolan bypss fitting yesterday. It was a bear. I eventually had to cut the fittings because there was little to no room and the tools i had did not work.
I drained and replaced coolant and ran it for a bit and it ended up running hot again. Reservoir drained, added more coolant and water mix and let it sit. Ran hot again.
I and trying to figure out what the problem is myself. I was thinking the thermostat but will check the water pump.
Thanks for the information and i'll keep reading and posting if i have any updates.
2004 Z71, 206,000 miles.