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2002 Honda Civic.
* With temperature control set to full “HOT”, if I rev the engine, I hear the gurgling/bubbling sound from behind the dash. I’ve read before that this is often because of air trapped in the system.
* No visible coolant leak. No “wet carpet”. No window-fogging while using defroster. No engine overheat.
* I get heat when the car’s moving. While standing still it’s run coldish on me a few times. Not always.
* My noise goes away when the temperature control is at full “COLD”. Should I infer from this that the air is in the heater core and not in other parts of the cooling system?
* I tried “burping” the system, and bubbles emerged from the radiator. The bubbling noise reduced somewhat after this, but is back now.
* MOST DISTRESSINGLY – with temperature control to full “HOT”, I’ve driven around for a week. And now I noticed that my coolant reservoir was almost empty, even though I’d filled it to the line a few weeks back. Note – I always check coolant level first thing in the morning, completely cold engine.
* I’ve decided to drive for one week with the temperature at full “COLD” to see if I lose any coolant. If I don’t, is it safe to say that the leak, if any, is in the heater core part of the circuit?Any advice would be appreciated. Need to fix this on a budget, without throwing a bunch of parts at it!
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If you had air in the engine’s cooling system, each time the engine was allowed to cool, the cooling system by itself will pull coolant from the jug. Better you start off with a full cooling system but this will also get you there. So disappearing coolant from the jug doesn’t necessarily mean you have a leak. So, refill the jug to the full mark.
I make a habit of keeping my garage floor clean enough so anytime I back out, if I see a puddle, I stop and investigate. This means I investigate plenty of condensed water puddles during the summer A/C season but it also means I catch any leak as soon as it starts.
[quote=”Chakraborty” post=82434]2002 Honda Civic.
* With temperature control set to full “HOT”, if I rev the engine, I hear the gurgling/bubbling sound from behind the dash. I’ve read before that this is often because of air trapped in the system.
* No visible coolant leak. No “wet carpet”. No window-fogging while using defroster. No engine overheat.
* I get heat when the car’s moving. While standing still it’s run coldish on me a few times. Not always.
* My noise goes away when the temperature control is at full “COLD”. Should I infer from this that the air is in the heater core and not in other parts of the cooling system?
* I tried “burping” the system, and bubbles emerged from the radiator. The bubbling noise reduced somewhat after this, but is back now.
* MOST DISTRESSINGLY – with temperature control to full “HOT”, I’ve driven around for a week. And now I noticed that my coolant reservoir was almost empty, even though I’d filled it to the line a few weeks back. Note – I always check coolant level first thing in the morning, completely cold engine.
* I’ve decided to drive for one week with the temperature at full “COLD” to see if I lose any coolant. If I don’t, is it safe to say that the leak, if any, is in the heater core part of the circuit?Any advice would be appreciated. Need to fix this on a budget, without throwing a bunch of parts at it![/quote]
Try this first
You may need to do a pressure check to find if you have a leak (which I suspect you do)
I really like the basic advice to properly burp the system and do a pressure test looking for the source of a small leak. I once had a pinhole leak (in one of the heater hoses) that had a ball valve effect, such that it would only leak when the system cooled at night, under negative pressure. Air was drawn in at night after the engine cooled, and my only symptom was a gurgling heater core. One place you might check would be at the radiator cap, which would be an inexpensive fix if it’s leaking there. Also have a look at the rubber hose joining the coolant reservoir and the radiator.
The thing is nobody has a pressure tester. If you do buy one you then find you need to order the adapter for your car.
I wish this was a common tool because most vehicles are operating with defective pressure caps.
What you describe are the CLASSIC symptoms of air in your cooling system. Follow the steps in the video that was posted and then recheck for the problem. Sometimes coolant just gets low. You don’t always need a pressure tester to find the source of a coolant leak. Coolant is very good about leaving stains where it leaks from. Many times you can find a coolant leak with just a good visual inspection. Keep us posted.
http://www.ericthecarguy.com/faq/solving-automotive-hvac-problems
http://www.ericthecarguy.com/faq/what-to-do-when-your-engine-overheats
Hi Eric,
Thanks for your advice. I’d already seen your Youtube video and tried burping the system, although it was a little more difficult for me because I didn’t have the no-spill funnel that you used. Where did you get that by the way?
In your opinion, what could be causing the gurgling sound only when the heater knob is set to full HOT, but not when it is set to full COLD? And is it ever possible that the drop in coolant level happens only with the full HOT setting, but not the full COLD?
Unsure where you live. But I’ve used the O’Reilly’s loan a tool program to rent their coolant pressure tester for my 98 Accord maybe similar to your Honda cap fit? They just hit your credit card while you borrow the tool and return it in 48 Hours. If no O’Reilly – Napa, PepBoys and Autozone all loan this type of tool.
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