What is causing a gurgling sound through my air vents

RAYRAYBABYBOI13

MEMBER
1999 JEEP LIBERTY
3.7L
V6
4WD
AUTOMATIC
152,000 MILES

When I sit inside the vehicle and turn it on and turn the heat on you can hear a running water like gurgling noise through the center dashboard air vents. I never heard it before. Also on the top of my coolant reservoir near one of the top air hoses I can see the coolant bubbling in there. I’ve looked underneath the car while I’ve had it on and I’m not seeing it leaking from anywhere. Does this mean something is the matter with my heater core?

Sunday, April 21st, 2019 AT 7:33 AM

3 Replies

ASEMASTER6371

MECHANIC
52,796 POSTS

Good morning,

The noise is the coolant boiling in the heater core from the coolant being too hot.

https://www.2carpros.com/articles/how-an-engine-thermostat-works

I would start with a thermostat replacement as it may not be controlling the temperature of the coolant.

https://www.2carpros.com/articles/replace-thermostat

I see no Liberty listed for 1999 so I looked up a 2009 which is the same for all 3.7 engines.

Roy

Do not waste reusable coolant. If solution is clean, drain coolant into a clean container for reuse.

If thermostat (3) is being replaced, be sure that replacement is specified thermostat for vehicle model and engine type.

1. Disconnect negative battery cable at battery.
2. Drain cooling system See: Cooling System > Procedures.
3. Raise vehicle on hoist.
4. Remove splash shield.
5. Remove lower radiator hose clamp and lower radiator hose at thermostat housing.
6. Remove thermostat housing mounting bolts, thermostat housing and thermostat.

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