You have received counting your mechanic three wonderful answers NOT!!!! I have been a mechanic for over 45 years. If there was a blown head gasket you would experence the gushing problem in less than 10 minutes. The rust on the spark plugs is from bad gas (water in the fuel) Tell your mechanic to go back to basic spark plug diagnosis school!!! Believe it or not there is a chart with pictures from all the spark plug manufacturers that teach how to read deposits on spark plugs.
You should start with the most simple, replace the radiator cap. It many be bad and allowing pressure to escape lowering the boiling point. You have a pressurized system because water under pressure will NOT boil at 212 deg f. That is why the water temp gauge if you have one and not an idiot light, goes to 240 deg. If your still have a problem after that you will need to check a coulpe of things. If you have a fan clutch that is if your model has the fan assembly attached to the water pump and fan belts and pullies, you can determine that by (WITH THE ENGINE OFF) try to spin the coolant fan. If the fan spins freely change the fan clutch because the fan is not spinning fast enough to pull enough air through the radiator during city driving. If your car has an electric cooling fan ( you can tell because the fan is not attached to the engine) run the car in the driveway until it starts getting hot (over 225 deg) the electric fan should turn on. If it doesn't either the fan motor is bad, the temperature switch (Sensor) for the fan on the engine is bad or the fan relay is bad or the fuse for one or the other is blown and there is no electricity to run the fan. If you have AC turn the AC on with the ignition key on, as the system has an override relay that turns the fan on instantly when the AC is active.That will help you to troubleshoot. If the fan runs with the AC on then the engine fan temp sensor is the suspect. If the fan runs with the AC on the fan relay and fuse would be ok.
Be careful, your mechanic could be taking you for a ride. If your head gasket was blown, the coolant would be mixing with your oil and your car would stop running shortly after. Check the oil stick to see if you see the coolant mixed with the oil (muddy color not light or dark oil). If in doubt wet a second opinion. If you have been driving your car under this condition more than 2 or 3 days your care does not have a blown head gasket. Check to see if the oil is low, the thermostat may be defective or you have problems with the radiator (check for leaks). Start with the most simple solution.
Perhaps your overflow tank was filled with coolant above the full line. Some times the radiator may release some of the coolant into the overflow tank when the engine gets hot. But, if the over flow tank is to full it will be released out of the tank through the overflow hose.
Another reason may be because your oil may be low and as result your car over heats and the coolant gets deposited into the overflow tank in large quantity thus expleeling it through the overflow hose.
Where is my antifreeze going???
I have a 96 chrysler concord 3.5 L and it is somehow losing antifreeze. There are no visible external leaks, and the oil doesn't appear to have antifreeze in it, as it is brown like it should be. There is no white smoke at all, so the coolant is not leaking into the cylinders. I replaced the thermostat about a week ago and it didn't help with the disappearing antifreeze. In the past 2 days we've used probably close to a gallon of coolant, and we have no idea of what the problem is and where the coolant is going. Any suggestions at all would be great.
If you just added to it it may do that for awhile until it is at the correct level. If not
you have a cooling systen problem.
I have a 2005 dodge magnum that I just replaced one of the fans because it was making aloud noise. Now I'm having problems with my car over heating the only leak I can see is from the hose that is connected to the
Reservoir water tank. Could that be the cause of why the car is over heating?
Help: What would cause coolant to pour out of the back of the engine on 1999 Ford Ranger. This happened today while idling there hasn't been any signs that anything was wrong until the coolant started to flow out. The heater was on and air coming out of it smelled like coolant. There wasn't any signs of leaks on the garage floor underneath it.