sisters car wont start?

If the engine won't start because of a bad head gasket, the head gasket would have to be very bad. That's easy enough to check. Take the pressure cap off the plastic coolant tank and watch the coolant level inside while you have a helper crank the engine. If the coolant pumps up and down when the engine is cranked the head gasket is in very bad shape and is preventing the engine from starting. If not, the engine is refusing to start for some other reason. I've seen lots of bad head gaskets but only the ones that actually pump coolant are bad enough to keep the engine from starting.

From that point it is the normal troubleshooting procedure. A burst (about a 2 second spray) of starting fluid on the air filter before closing up the air cleaner box is a good place to start. If the engine runs for a couple seconds and dies that means all it needs is fuel to the engine. Otherwise it is time to look at the spark.

Her 2004 Malibu has the GM Passlock system that has been used by GM since 1996. It can be very problematic but if it is killing the engine it should flash a red light on the dash, with a label like "Theft Warning." If that is happening, use the procedure in the first source.

Did she drive the vehicle until it stopped when overheated?

If so she probably seized the engine, check the oil cap for white gray matter, if so, there is water in the engine.

Did she see white smoke coming out of the exhaust before the engine stopped? If she did, she blew a engine head gasket.

First, ensure all connections from the battery to the motor are tight and blank. There aren't any unfastened hoses or wires or connectors and the dipsticks are seated appropriately of their holders. The water stage within the battery is proper. Second, have the vehicle pc codes checked to look if there's some thing incorrect with the ignition or consumption methods. Third, take out the battery and notice if it begins one other vehicle comfortably. If the battery has difficulty commencing one other vehicle, the charging approach demands to be checked and the battery would possibly want changing. If the battery begins one other vehicle comfortably then it could be regarded to be OK. If the battery is OK the following factor that would be incorrect is the starter motor, it demands to be checked to look whether it is drawing an excessive amount of vigour from the battery. Carefully consider it after the vehicle begins, is it very scorching? if this is the case, the starter would possibly want changing.

more details would help but yes it could be a bad head gasket or cracked block or head and it also could be the thermostat is casing the problem but she should have go ting it checked out be for she overheated her car but the damage is done now and it will take some time to get it repaired now over a 25 doll are thermostat that was midsection its going to cast Alto more now hope that it isn't the case but dint look good for her right now

check the oil if its milky white you probably blew a head gasket but if the car wont turn over your seased up and out of luck.

even if it wont turn over, it dont mean its siezed. it could be hydrolocked