I got out of my car (96 civic ex auto) this morning and noticed coolant coming from under my car. I went to check under the hood and the overflow was gurgling and spitting out coolant. Later today I bought a new radiator cap but that didn't help. I got home and it was still gurgling but this time I noticed a pinhole leak in a metal line that goes to the bottom of the throttle body.

Is it possible that this pinhole leak is causing this gurgling? All temps are normal all the time, I just want to rule out the pinhole leak before I go and replace the head gasket.

 

Doubtful.

 

yeah I don't think that would cause the gurgle time for a new hg anyone?


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May be multiple problems. You can pressurize each cylinder with air and watch for air bubbles in the radiator, also check for signs of coolant in the oil.

Keep in mind, if coolant is getting out through a pinhole, air can get sucked back in through the same hole

 

I suppose fixing the hole will not hurt and trying that out. If, as I expect, it doesn't work then it'll be head gasket time.

 

After running for a bit, this is the condition of my coolant. Apparently the previous owner liked to run tap water. I disconnected the upper and lower to the radiator, removed the thermostat and disconnected the heater core hoses, which hasn't been used in a few months. The heater core was the worst, but I got all of the red/corrosion out by manual flushing with a hose (forward and reverse flushing). I then got some coolant system flush and connected all hoses and left the thermostat out, filled with water and flush and ran for about 8 to 10 miles total.

Returned and took the cap off, and this is what started again below

 

HG right?

 

try putting compressed air in each cylinder and watch for the gurgle as the final test if it gurgles it could be a hg, cracked sleeve, or warped head/block. if its not gurgling then back to the drawing board


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Unfortunately I do not have access to an air compressor as of this moment. I did go and rent a combustion leak tester to see if the gurgling is combustion gas leaking through the head gasket into the coolant system. The test came up negative after about 10 minutes of sniffing with the tester.

Blue means no gas was detected, yellow would signify that combustion gas was detected.

After copious amounts of fresh water flowing through the cooling system (by way of water hose), I believe I may have dislodged a obstruction or two. As of today, after filling the system back up with flush and water, the cooling system is acting as it should. I am going to run the flush on my way to work tomorrow and come back and do a fresh water manual flush to ensure all deposits are out of the system and fill with 50/50.

I'll continue updating this for others to reference if they have the same symptoms.

 

To conclude: the issue ended up being a corroded radiator, courtesy of previous owner's tap water in coolant system. Replaced radiator, one month later still no issues. I highly recommend the leak down test.