I have a 2003 Tracker with the 2.0 4 cyl engine....For the longest time I hear gurgling in the heater core with luke warm heat...Any threads or comments on this topic??

 

you have air in the heater core. does the cooling system use a pressurized surge tank?

best way to fix it is to vacuum fill the cooling system. without a vacuum filler...top up the system if its low and run the engine at 2000rpm until the thermostat opens, shut it off and leave it overnight...let it cool overnight. If air is still present you may have to remove the heater core outlet hose, start the engine to flow some coolant thru the core...just don't break the heater core taking the hose off 10 year old heater core tubes are fragile and you don't want to have to remove the dash to replace it.

 

You aint joking about that. Those plastic ends and tube heater cores that Chevy used on the pickups back in the 1990's were prone to leaking at the seals.

 

Thanks for the reply...I failed to state my efforts to resolve on what I have done....I purchased and used, a large funnel kit that had a radiator cap attachment so that the funnel could be connected firmly on the radiator...I then drove the vehicle on ramps so that the nose would be higher than the rest of the vehicle...I let it run, squeezing the top & bottom hoses to help it purge, shut it off. It sat over night & repeated the process....There is no way I will tamper with the heater hoses for fear of consequences. The hoses are clearly visible on the firewall but disappear towards the back of the engine... I guess one would have to be a magician to change them....The Tracker has 57,000 miles and is in excellent condition and well maintained... This gurgling has me stumped......

 

then buy the proper tools or pay for professional to vacuum fill the system. all new vehicles should be vacuum filled to avoid trapped air.