SOURCE: No interior heat / engine overheated 97 dodge ram 1500
Coolant runs through the heater core regardless of whether or not the thermostat is open or closed. Otherwise your heat would work poorly in cold weather as the heater would stop working each time the thermostat closed to let the vehicles engine maintain the necessary temperature for efficient operation.
Thermostats also don't make noise when they open or close, so the noise you're hearing is not the thermostat.
The noise you're hearing is probably air moving through the cooling system. This happens when you're radiator is low on coolant. The same coolant that keeps your engine cool is also what delivers heat to your heater core. When the system becomes too low on coolant, there's nothing to transfer that heat away from the engine so the engine overheats and the heater stops working. There is probably a little coolant still in the system, which is why you're hearing noises as the water pump continues to try and pump whatever it can. As bubbles of coolant make it through the system, you'll notice the engine temperature fluctuate up and down.
Often times in older vehicles, the fill line that runs from the plastic reservoir to the radiator becomes plugged, so you may have plenty of fluid in the reservoir while the radiator may be nearly empty. You have a very slow leak somewhere. I have a slow leak on an old Jeep of mine, and it runs fine until one day the level of coolant drops below the point where the water pump can easily pump it, and I begin to experience the exact symptoms you describe: Strange noises, heater doesn't work, engine temp runs hot then falls, etc.
Another possibility is that your water pump is damaged. A damaged water pump will not pump well, preventing coolant from flowing through the system. As the pump spins very quickly since it's driven off the engine, a damaged or out of balance pump can often make pretty noticeable noises.
SOURCE: Heater Problums with the smell of burning Antifreeze.EXTRA Detail
Hi!
I really feel you could be losing a small amount of coolant from the heater matrix/core.
It
appears we have an Air lock scenario due to this and you will need to perform a
system Bleed.
Park
the vehicle on level ground, when cold remove coolant filler cap,
start engine and leave to idle, turn heater on full and blower to
max. When engine reaches operating temperature watch and listen near
coolant filler, keep clear as gurgling and hopefully a boil over
should occur. Top up with very warm coolant and wait as it may do it
again.
Check
for heat inside vehicle if warm replace coolant cap but keep an eye
on temperature gauge as the ~Air lock may have moved on from heater
matrix/core so proceedure needs to be carried out again from COLD.
Also with your temp gauge reading 1/2 this is normal, possibly the core is blocked or as already suggested leaking, a Radiator sealing additive might help BUT it may be the cause of your cold/warm air?
TOO MUCH SEALER blocking the Matrix/Core?
I hope all this helps!
Please
press the Blue button to appraise my FREE Efforts, Thank You!
Paul
'W' U.K.
SOURCE: had antifreeze leak now car wont start
ur vehicle overheated.. ur timing belt and or water pump may be broken and or worn..take the vehicle to a reputable repair shop or dealership
SOURCE: Frontier 2000 2.4L King Cab 100K miles. Temp
I've had problems with Datsun (later Nissan) engines hanging the closed thermostat until it boiled, then the thermostat released and operated normally. If you increase the small vent hole in the thermostat valve plate a small amount, the problem disappears. It seems that steam from engine operation gathers behind the thermostat sensing bulb and delays opening. The increase in vent hole size lets the steam through and allows the hot water to open the valve. Hope this helps!
Testimonial: "Thanks for this possible solution. I'll give it a shot."
SOURCE: coolant smell inside cab when you turn on car/heat
Likely you are in the beginning stage of a heater core leak. at this point, you may be able to temporarily solve the problem by using a good system sealer (I'm partial to the kind that comes as a silver powder) Since we don't actually know the condition of the core, temporary may mean a week or several years, but replacement is expensive and time consuming so I'd definitely give it a try.
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