Out of know where my car keeps over heating. It did it like twice a few months ago, and didn't do it since then. Now, yesterday and today it did it again. I noticed the temp gauge is real sporadic, and goes up and down a lot. Also, when it overheats I notice there is antifreeze coming out of the hose by the spark plug closest to the firewall, on the passenger side.

Anyone have any idea what this is?

Oh, it's a 99 grand marquis.

 

sounds like you've either got a glob of goop flowing around and sporatically plugging the system in spots, stuff plugging the heater core, or a bad thermostat. sounds like it's time for replacing the thermostat and giving it a through coolant flush. You may need to replace the hoses too.

 

Heres a couple more symptoms I don't really get. I was running the heat on full blast but it was blowing cold air. All of the sudden it would start BLASTING heat out, and then the temp gauge would drop really fast.

I was also thinking the thermostat, but it just seems different than the regular old sticky thermostat.

 

if you have the automatic controls, the heater control valve could have issues (could be called something different... but it's the one on the heater hose that has a vacuum line plugged into it and a wire harness on the other end inline on one of the heater hoses).

You'll definitely want to take care of that before it overheats again. those aluminum heads like to warp when they get hot and that can lead to massive headaches (blown head gaskets). It sounds like the pump is fine, but does sound like the thermostat is sticking and being blown open due to excessive pressure in the system. The same issue may be affecting the heater valve as well. taking excessive pressure build up to open it.

 

So you think I just need to replace the thermostat? Not sure what you mean by automatic controls. If you mean the A/C heater *****, then they are manual. I don't have a digital automatic thing.

 

it would say automatic temperature control on the control panel if it was. I think you may need to replace the thermostat AND have the system flushed for good measure to help prevent other problems. And since you've been having this problem, check the hoses for cracks, bulges, and leaks. If you don't get this fixed soon, it may lead to way more costly repairs.