# Help! car overheating! **URL:** \ **Category:** Factual Questions\ **Created:** [October 3, 2011, 2:10pm UTC](https://boards.straightdope.com/t/help-car-overheating/598431 "2011-10-03T14:10:06Z")\ **Posts on this page:** 3\ **Page:** 2
**Author:** ![andyleonard](https://avatars.discourse-cdn.com/v4/letter/a/e19b73/32.png) [@andyleonard](https://boards.straightdope.com/u/andyleonard)\ **Post date:** [October 4, 2011, 1:34am UTC](https://boards.straightdope.com/t/help-car-overheating/598431/21 "2011-10-04T01:34:56Z")
IF the head gasket has failed, ONE of the places it could fail is between the combustion area and the coolant area. If your car were drinking the water - with no trace of where it went - you probably would have a leaking headgasket, allowing the intake stroke to suck in water and blow it out the tailpipe. When you put external pressure in the cooling system - whether it’s from the tester or from heat - you are forcing coolant into the cylinder…or wherever else it’s going. If you remove the sparkplugs and pump the radiator pressure up to 15psi and you sit there for 15 minutes, the pressure will either stay at 15psi - in which case your cooling system is tight and you need to look elsewhere for the problem - or the pressure will drop as the coolant and air leaks where ever it’s leaking to. If you see it dripping out of a crack in the radiator (common) or needling out of a hose (common) you can fix it. If the pressure is dropping and you don’t see the drips, since it has to be going somewhere, you suspect the inside of the motor…and you hit the starter, spin the motor and see if the missing water squirts out of one of the sparkplug holes. That’s the full diagnosis of a blown head gasket…and why you remove the plugs for the pressure check. ---
**Author:** ![excavating\_for\_a\_mind](https://avatars.discourse-cdn.com/v4/letter/e/e8c25b/32.png) [@excavating\_for\_a\_mind](https://boards.straightdope.com/u/excavating_for_a_mind)\ **Post date:** [October 4, 2011, 2:53am UTC](https://boards.straightdope.com/t/help-car-overheating/598431/22 "2011-10-04T02:53:22Z")
A minute of two of googling found this on the Misubishi 3.0 L V-6 [Chrysler Mitsubishi 3.0L V6 Engine](http://www.aa1car.com/library/2003/us100344.htm) > [@](#): > > Something else to pay close attention to is the radiator and cooling system. If the original engine failed due to overheating, the radiator may be clogged and may have to be cleaned or replaced. Also, when refilling the cooling system, make sure all of the air is out of the system before the vehicle is driven. Check the operation of the cooling fan, too, to make sure it comes on when the engine is hot and when the A/C is turned on. And at the bottom of the page > [@](#): > > Air Bubbles In Cooling System > > Many 3.0L alleged head gasket failures appear as air bubbles in the cooling system. The cause of these failures on the 3.0L Mitsubishi engine have typically been attributed to a cracked cylinder head or a leaking head gasket. However, this is not always the case. This engine has two inlet coolant pipes that connect from the heater core and the rear of the engine to the water pump. The pipes are located in the valley of the cylinder block. These pipes are sealed with O-rings on the ends and become easily distorted when the engine is disassembled. If the pipes become distorted or the O-rings are not replaced air can enter the cooling system immediately after start-up. > > To check for this after air is detected in a system, check for hydrocarbons in the coolant. If no hydrocarbons are present, look for these pipes to be leaking. Most autoparts store will have a device you can attach to the radiator that has a chemical you put in it that will change color if exhaust gasses are present. This is what they mean by 'hydrocarbons in the coolant". As mentioned above, you need to make sure it will fit your radiator, ask the autoparts guy when you buy it. Most local mechanics can do this test for you, probably for around the cost of the device. Ask for the test, since some may decide you have a head gasket problem (which you may have) without the test. Google around for some mini-van message boards. Most of the older models are being taken care of by backyard mechanics and they can be a wealth of information. You may even find some in your town that can help. excavating (for a mind) ---
**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\ **Post date:** [October 4, 2011, 3:33am UTC](https://boards.straightdope.com/t/help-car-overheating/598431/23 "2011-10-04T03:33:58Z")
I came back to say often head gaskets will not billow smoke or other obvious symptoms. I had a car in the shop last week, overheated, blown head gasket and no obvious symptoms except it used water. I came back to mention a hydrocarbon test. One word of warning about having a hydrocarbon test done, the colored fluid is only good for a period of time (a year?, I don’t recall) If the shop has a bottle older than that, it won’t detect a leak no matter how bad it is. [Previous page](https://boards.straightdope.com/t/help-car-overheating/598431.md?page=1)