Blown HG? - Lexus IS Forum
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post #1 of 2 (permalink) Old 07-12-2019, 10:37 AM Thread Starter
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Blown HG?

I was driving the freeway and when I look down I notice my temp gauge is at the beginning of the “RED” therefore I jumped off the freeway parked and let the car sit. I go out to find coolant all over the ground in which it flowed out of the rad cap and from the bottom of the radiator. I believed it was my thermostat so I had replaced it, but that was not the case. The car still overheats and now has a misfire. It is throwing the code P0300, which I have found to be a (random misfire) correct me if I’m wrong. I have just replaced the spark plugs and wires, and valve cover gaskets just to be safe. Is it possible my head gasket is blown? Or my water pump is not working correctly? We had checked the rad hoses when running to find that they were both scorchingly hot. Any advice would be greatly appreciated. T
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post #2 of 2 (permalink) Old 07-12-2019, 11:59 AM
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You may have a blown head gasket, but it is likely a symptom of your cooling system failure, and not the cause.

You need to perform a leakdown or compression test; preferably a leakdown test. That will tell you if you have a blown head gasket. Repair/replace as necessary.

Once you have confirmed the head gasket isn't an issue, you need to find the source of your cooling system leak, which is likely a cracked radiator.
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