Hey everyone, I have a friend who owned a 2010 Hyundai Elantra, great little car up until recently when she was informed it has a small head gasket leak. It’s up there in miles and cosmetically not perfect, so she was going to scrap it… But, I told her I’d buy it for scrap price so I can screw around with it. Anyways, no oil/coolant mixture, very slowly lost coolant. First thing I did was drain and fill x 3 the coolant, then I added Blue Devil gasket sealer. I’m super pissed because I used the version that doesn’t require you to remove the thermostat, but I’m pretty sure it screwed it up anyways because after putting the sealer in and following the instructions exactly, letting the car go cold again, I took it for a test drive and now the car is overheating AFTER the sealer was put in, which is never did before. So at this point, I pay $150 to tow it home, and I put a new thermostat in. I know I need to “burp” the cooling system, so I let the car idle with the heat on and the radiator cap open, and added coolant till it stayed at a consistent level. Is there anything else I need to do as far as making sure all the air is out, I figured I’d fill the radiator to the top if it’s low after I let the car get cold again. Anything else I need to check or do before trying to drive it again? And if it’s overheating while I have it idling and am adding coolant to the radiator, would the temp light still illuminate even tho the radiator cap is off? For whatever reason, the geniuses at Hyundai decided to skip a temp gauge on this year of the Elantra. Thanks so much in advance, and yes I know gasket sealer isn’t usually smart but the car was going to be scrapped anyways so figured why not lol.