Heater Core gurgling sound
#1
03-22-08, 10:45 AM
Heater Core gurgling sound
1994 Chevy P/U; 5.7 V8 engine. I was smelling antifreeze earlier after I had taken the truck for a drive. No signs of leaks on the floor or anywhere for that matter. The mechanic determined it was the water pump and replaced it as well as the radiator cap. I have since driven the truck about 200-300 miles. I now have a gurgling sound from the heater core area. Sounds like fluid passing through the coils. It seems to gurgle right after accellerating from a stop, or just really getting on the gas. Any ideas what is causing the noise?
#2
03-22-08, 11:07 AM
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I'm not a mechanic, so let the others chime in, but from experience, that gurgling has been a bad heater core for us. We've had two vehicles exhibit that sound and both needed a new core.
#3
03-22-08, 11:26 AM
Try backflushing the heater core by reversing the flow of water through it. You will have to take both heater hoses loose from the motor end and force water through it via a garden hose. You will probably get a group of crap out of it. I had a similar problem on a K1500 once, and it helped.
#5
03-22-08, 05:08 PM
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it's most likely low on coolant. check your expansion tank first when COLD 
if the tank is low, top it off with a 50/50 mixture of coolant and water. (ps, don't buy the premixed 50/50...it's the same price as anti freeze; therefore costs twice as much!). if the tank is at or close to the full mark...
then remove the rad cap and check the level in the radiator. if the radiator is low and the tank was ok, then the cap is bad...top off the coolant and replace the cap. if the rad is low and that tank is empty, top off both and, reinstall the cap and take a it for a drive. once up to operating temp you can park it on a level place and let it cool off...recheck the level in the tank and top off as necessary...letting it thermal cycle is the key to getting the rad all the way full. now keep an eye on it for a few days and all should be well.
if the tank is low, top it off with a 50/50 mixture of coolant and water. (ps, don't buy the premixed 50/50...it's the same price as anti freeze; therefore costs twice as much!). if the tank is at or close to the full mark...then remove the rad cap and check the level in the radiator. if the radiator is low and the tank was ok, then the cap is bad...top off the coolant and replace the cap. if the rad is low and that tank is empty, top off both and, reinstall the cap and take a it for a drive. once up to operating temp you can park it on a level place and let it cool off...recheck the level in the tank and top off as necessary...letting it thermal cycle is the key to getting the rad all the way full. now keep an eye on it for a few days and all should be well.
#6
03-22-08, 07:07 PM
The tank and radiator are both full. According to someother blogs, it might be an air pocket in the heater core.They suggested a couple different ways to purge the air out of the system that I'm going to try. If that doesn't work, I'll do as chandler suggested and flush the heater core.
#7
03-22-08, 08:14 PM
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Like Chandler said, back flush your heater core. My buddies Blazer was doing the same thing and black flushing cure it.
#9
03-24-08, 04:11 PM
I checked the antifreeze level in the radiator yesterday after the engine had cooled off from the previous day. It was a little low so I topped it off. Today I hardly noticed the gurgling sound. I will check the antifreeze againg later after the engine has cooled off again.
#10
03-24-08, 07:04 PM
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Both those cores I mentioned were leaky, and on acceleration and whatnot they made that same sound. Classic symptoms, antifreeze vapor from heat - that smell is unmistakable lol. First vehicle we were told that it was the head gasket. Had it done, and money well wasted.
