- Joined
- Aug 9, 2022
- Messages
- 166
2015 Jeep Wrangler 3.6L V6 with 170K miles. I heard some gurgling sounds in the heater core a couple times upon starting the vehicle at work, so I decided to pull the radiator cap even though the coolant level in the overflow bottle was above min. There was no visible coolant in the radiator, and it probably took around a quart to refill. The bottom of the radiator cap and the radiator neck were covered fairly thickly in black particles that would smear when wiped off with a cloth. I am not sure how long the radiator was low on coolant, because the last time I had the cap off was around two years ago. I did have to refill the overflow bottle several times over the course of that period.
I have been driving it to work after I refilled and bled air from the system, and I am finding that the level in the radiator drops around 1 inch below the radiator neck after each drive, the overflow bottle has a higher level, and some of the black particles return under the radiator cap. I decided to pressure test the cooling system hot and also perform a block test. The test fluid turned a greenish color during the block test after 1 min, and I lost about 1 psi in 2 mins and 4 psi in 10 mins during the pressure test. I have identified a small pinhole leak in the radiator on driver side, so I believe that coolant is being pushed out to the overflow bottle and not getting drawn back into the radiator upon cooldown.
My main concern is the returning black particles under the radiator cap and the fluid color change during the block test. The instructions say the fluid should turn yellow, but I am seeing that it is more like a light green. When running the test I would squeeze the bulb, and it would stay like that for about 20 seconds when some air bubbles would come up through the tester to reinflate the bulb. I would squeeze the bulb again and it would repeat, but each time this happened you could start to notice the color change. Does this definitively indicate that I have a blown head gasket, and what I am seeing on the radiator cap is soot from combustion gas getting into the cooling system? The engine has never been overheated based on the coolant temp gauge, and if I monitor coolant temp with my scan tool while driving it will fluctuate in the normal range between 200-209.
I have been driving it to work after I refilled and bled air from the system, and I am finding that the level in the radiator drops around 1 inch below the radiator neck after each drive, the overflow bottle has a higher level, and some of the black particles return under the radiator cap. I decided to pressure test the cooling system hot and also perform a block test. The test fluid turned a greenish color during the block test after 1 min, and I lost about 1 psi in 2 mins and 4 psi in 10 mins during the pressure test. I have identified a small pinhole leak in the radiator on driver side, so I believe that coolant is being pushed out to the overflow bottle and not getting drawn back into the radiator upon cooldown.
My main concern is the returning black particles under the radiator cap and the fluid color change during the block test. The instructions say the fluid should turn yellow, but I am seeing that it is more like a light green. When running the test I would squeeze the bulb, and it would stay like that for about 20 seconds when some air bubbles would come up through the tester to reinflate the bulb. I would squeeze the bulb again and it would repeat, but each time this happened you could start to notice the color change. Does this definitively indicate that I have a blown head gasket, and what I am seeing on the radiator cap is soot from combustion gas getting into the cooling system? The engine has never been overheated based on the coolant temp gauge, and if I monitor coolant temp with my scan tool while driving it will fluctuate in the normal range between 200-209.
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