Cooling system repair on most cars ranges from fairly simple to quite difficult. As backyard mechanic, you may want to go slow in doing cooling system repairs if you complete the easy stuff and still have a problem. It might be time to turn it over to the professionals for help. However, depending on your experience level and bravery, you might find that you can tackle bigger cooling system problems than you realized.
Look for the obvious.
All cooling system repairs should start with raising the hood while the car is hot and looking for leaks. This may seem remedial, but it is often the best way to determine if the leak is going to be easy to deal with or difficult. If you see steam rising from a hose, you know that it will need to be replaced. That will usually be the end your problem. You need to be aware that frequently hose leaks can only be seen when the car is hot. The coolant that leaks out will evaporate from the engine heat and be tough to see when the car cools.
Locate the water pump and inspect it for coolant leaks.
On forward mounted engines, the water pump will usually be where the fan attaches to the motor. On sideways mounted engines, the water pump will usually be in roughly the center of the engine on the end where the belts are located. You can recognize most water pumps because the heater hoses are attached to them. Normally, the thermostat will be located at the end of the upper radiator hose and be right above the water pump. If you cannot be sure, go to your auto parts store and they can generally give you guidance.
Water pumps weep coolant or may have a gasket leak.
The water pump on your car is designed to leak coolant if the internal seals begin to fail. This signals the end of the water pump’s life. It also alerts you to the fact that the pump has become inefficient and will no longer circulate your coolant to keep your car’s temperature in check. The only solution is to remove everything that is in the way and remove and replace the water pump. On some cars, this is a job that takes about 45 minutes. On others, it can require a few hours. Make sure that you get the gasket for the water pump on correctly to prevent leaks. You will need to work to completely remove all the remnants of the old gasket. Use a scraper to do a good job with this.
Put a large piece of card board under you car when you park it.
You may have a problem with the freeze plug on the lower part of your engine block. If it is leaking, a big piece of card board placed under your car beneath the engine will show spots from engine coolant. If all of the coolant seems to hit the same spot, take your car to a mechanic and have it checked with the car up on a rack. This is the best way to access the freeze plug and replace it.
With the car warmed up, check the radiator for leaks.
If the rest of your cooling system is in good shape, a radiator leak will manifest itself as either stream of fluid spraying out or running down the radiator. Sometimes, the sprays will be vaporized and be steam. Never inhale steam that is coming from any part of the cooling system. It contains antifreeze which is extremely dangerous to humans when breathed or ingested. Not all radiator leaks are easy to spot.
You may need to have your system pressurized to find them. At times, the only sure way to find them is to remove your radiator and pressurize it under water and look for air bubbles. At this point, you can repair or replace it. Replacement is almost always the better and more certain solution.
Having eliminated hoses, the freeze plug, and the radiator, look at the thermostat.
This might actually be one of the first things you should check. Removing two or three bolts will give you access to the thermostat. Lift the cover away from the top of the engine. You will need to replace this gasket and scrape off the old one before bolting things back together. Pull out the old thermostat and drop in a new one. Replace the gasket and cover and bolt it down. This fix is over.
You may need to bleed the cooling system.
On some cars, trapped air can cause the car to overheat. Some Chrysler products and other types of cars have bleed valves on the cover for the thermostat or somewhere nearby. It is a simple process to loosen the valve and bleed the air until coolant flows out. Re-tighten the valve to close the system and you are finished. Most of the time this needs to be done after you have completed other work on the cooling system and allowed air into it.
If you are really unlucky, you may have a head gasket issue.
When head gaskets fail, several ugly problems can result. You can develop a cracked head that has to be replaced. The best case happens when the gasket fails to the outside and lets coolant leak from your engine. If the head does not crack, you will still have either a costly repair or lose many hours replacing the gasket. On most cars, you will have to replace the bolts that hold the head to the block also. If it leaks to the inside, you will not see coolant. Your car may have excessive amounts of white smoke pouring from the exhaust as coolant is vaporized in the car’s cylinders and pumped into the exhaust system. This type of leak allows coolant into your crankcase and requires an oil change at the same time that the gasket is replaced. It is almost always a good idea to change the oil after a head gasket leak as a safety precaution.
Hot coolant leaking into the cabin of the car is another problem.
This almost always happens on the passenger side of the front floorboard. Coolant will drip from beneath the dash and hit your passenger on the feet. This signals a heater core leak. The only solution is to replace the heater core. Take your time and figure out how difficult that this process is going to be. Most of the time, if you are not really a skilled mechanic, it is best to take it to a professional for installation.
Sometimes, your system just needs a good flushing.
Flushing the cooling system used to be more popular than it is today. However, you cooling system can accumulate a build up of material in the same way the your body can build up plaque in your veins and arteries. The only way to remove this from your cooling system is to give it a good flush with a high quality product. This is not a hard thing to do, but it does require time.