Mystery Coolant Leak

Jeep Monkey

Jeep Newb
i had a coolant leak on my 2008 that i found was the lower intake manifold gasket. when it was apart i found that it hadn't been leaking long as there were no real witness marks from it. after replacing that the visible leak stopped, and my MPG went back up to normal. however, i still seem to be going through coolant. i only know this because after a week or two of driving i start hearing a rush of coolant into the heater core on a cold startup. i have replaced the radiator, due to an unfortunate drill bit incident, and that is when i noticed a leak was possible (not sure if i was hyper aware of the coolant system or if it is related). i have seen witness of a leak at the rad cap (and have a new one on order today) but it never seems to be wet when i check it. the temp is fine and i dont see anything around any of the hoses i removed from either job. also, the overflow is always full and i have never had to fill it the last 3 years i have owned the jeep. i am using the correct coolant but not sure what has been done before me. the water pump is also new. i am lost in the coolant system and am wondering if anyone could point me in a new direction.

thank you
 

WillysJKJeeper

Jeep Owner
Whats ur water temp running does stay around the 220 area?
If your still hearing the waterfall effect in the heater core means there air trapped in the engine needs to be bleed out theres a bleeder screw on top of the thermostat housing to get some of the air out. Another way which works for me is to put the jeep on wheel ramps in the front so the radiator is up higher and the air will move into the radiator when u have the cap off with it running up to temp.
This funnel also helps in the process just keep coolant in it so u can see the bubbles come out and is less messy.
 

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Jeep Monkey

Jeep Newb
i use the funnel. i dont think the 3.8 has the bleed screw. the air introduced itself after i had already used the funnel parked up a hill with the passenger tire on the curb. i replaced the cap this weekend and used the funnel again. i will wait to see what happens.

the temp is normal operating temperature. most likely 210
 
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