Most modern cars have a pressurized engine-cooling system that uses a thermostat to control the flow of coolant throughout the engine. The thermostat stops coolant from flowing until the engine is warm and then regulates the coolant temperature.Why is the cooling system pressurized? Because the boiling point of a pressurized liquid is higher than that of a nonpressurized one. So the engine can safely operate at higher temperatures without boiling over. Unfortunately, a pressurized system means that all parts, including hoses, must be strong enough to withstand the higher pressure.The procedures in this article are typical for most modern cars. Refer to the manufacturer’s manual or an aftermarket service manual for specific instructions and details.As with other repairs, grab your handy-dandy car care toolbox. I’ll let you know if there’s anything special you need to make the repairs in this article.
What to Do with a Hot Car
Relax-I’m not going to tell you how to get rid of a stolen car, but your car may occasionally get too hot in other ways.
To make life somewhat easier, here are a few guidelines for troubleshooting cooling and lubrication systems:
- If your car always seems to run hot, first look for debris blocking the front of the radiator. Also check the seal on the radiator cap, test the radiator hoses, and then consider replacing the thermostat or water pump.
- If your car warms up slowly, the thermostat may be stuck open.
- If you must remove the radiator from your car to have it rebuilt, consider buying a replacement unit instead. It might be cheaper.
- Check the sides of the engine block for signs of coolant leaking through round metal parts called freeze plugs or core plugs. Refer to the service manual for instructions on replacing core plugs.
If you car’s heater doesn’t work after not being used for a while, find the heater under the hood or dashboard and check to see if the hose to it has a spigot or valve that’s closed.
If Your Car Is Radiating Too Much Heat … chances are you don’t have the specialty tools needed to repair your car’s radiator. If it needs repair, the best you can do is remove it and reinstall it. Radiators for most modem cars are a commodity; you can order a new one through an auto parts store and pick it up on Tuesday. The price is cheaper if you bring your old radiator in for an exchange. Until you do, most auto parts stores or radiator shops require a deposit called a core charge.
To remove and reinstall a radiator, follow these steps:
- Drain the car’s cooling system, If the coolant is relatively new and clean, save and reuse it. Some coolants can be poisonous to your pets.
- If your car is equipped with an automatic transaxle, disconnect the coolant lines from the radiator.
- Loosen the hose clamps on the radiator and detach the hoses. Some hose clamps require you to unscrew them; others require you to use a special pair of pliers to squeeze the wires until the clamp opens.
- Remove the engine cooling fan if it’s attached to the radiator.
- Loosen and remove the bolts holding the radiator to its frame.
- Look around for any other components that are attached to the radiator and remove them. Mark their locations and sources to make reinstallation easier.
- Lift the radiator from the frame, being careful not to spill coolant or to damage paint. Drain any coolant left in the radiator before taking it to the radiator shop or auto parts store.
- Reinstall the radiator in the reverse order in which you took it out.
- Refill the system with coolant, a SO/SO mixture of water and antifreeze.
- Start the engine. As it’s warming up, look for leaks.
- To adequately test the new radiator, drive to an ice cream parlor at least 25 miles away, park and check for leaks, and then go in and order while the system is cooling. When you system is cool, check it again, get a quart to go, and drive home. Warning: Rocky Road is a bad omen!
When Your Water Pump Doesn’t
The water pump’s job is to pump coolant through the engine and radiator. A water pump is actually a pretty simple part. A belt wrapped around the crankshaft pulley also turns the water pump shaft. Inside the pump, the shaft has a bunch (technical mechanic’s term) of blades. As the shaft rotates, the blades go around, moving the coolant forward. Pretty slick! The most common problem with a water pump is that the shaft wears out. On newer cars, there’s a sealed bearing on the shaft. On older cars, the water pump has a zerk or lubrication fitting that needs a shot of grease once in a while. A water pump that is going out tells everyone so, making lots of racket and leaking coolant all over the place. It’s a pretty effective warning system.
To replace a water pump, follow these steps:
- When the engine is cool, drain the cooling system. If the coolant is relatively new and clean, save and reuse it.
- Remove the drivebelts and, if necessary, the timing belt.
- Remove any other parts attached to the water pump.
- Remove the bolts holding the water pump in place. If one bolt is longer than others, make sure you remember which hole it’s from. Clean away any gasket or O-ring material on the housing or engine block.
- Install a new gasket and/or O-ring.
- Install the replacement water pump. Hand-tighten all bolts and then use a torque wrench to tighten them to the manufacturer’s specifications.
- Reinstall all parts removed to get to the water pump.
- Refill the system with coolant.
- Adjust the drivebelt tension.
- Just kidding. There’s no step 10. You’re finished.
Turning Up the Heat
A car’s heater simply circulates some of the hot coolant from the engine through a device that looks like a small radiator and then blows the resulting warm air to heat the interior of the car (see the figure illustrating this process). By this description, you can identify the main parts of a car’s heater: the heater core (radiator), blower motor (fan), and hoses. The first step to repairing a car’s heating system is to describe the problem (“Doctor, it hurts when … “). This helps define the solution. If the heater is leaking coolant into the car’s interior, for example, you know that replacing the blower motor is probably not the solution. Chances are the problem involves a hose or the heater core. Knowing that makes your repair job easier. Common sense will probably dictate the cure. Coolant leaking into the passenger compartment suggests there’s a leak in the heater or an attached hose. If you don’t hear the motor or feel air movement with the heater switch on, the blower should be checked.The second step is to apply the easiest solution first. In the example, check and, if needed, replace the heater hose or clamps before replacing the heater core. Cars really do make sense. Just don’t take their advice on money matters.
A car’s heater can be repaired following these steps:
- Inspect the heater system for blockages and broken parts. Make sure the heater hoses are in good condition. If your car has a summer valve on the engine block (which lets you shut off circulation to the heater core), make sure the valve is open.
- If necessary, check the blower circuit and motor. If the blower motor isn’t operating, check the fuse and all switches and wire connections. Some blower motors also have resistors that can bum out and need replacement; you can check them with an ohmmeter.
- If the blower motor needs to be replaced, follow the instructions in the service manual for doing so. In some cases, the dashboard must be partially disassembled. In all cases, you must first drain the cooling system.
- If the heater core needs to be replaced, again, follow the instructions in your car’s service manual. There are just too many ways of doing so to cover them all here. The heater core is typically found in a housing unit under the dashboard or in the engine compartment against the firewall. Disconnect, disassemble, replace, and assemble.
- To test your car’s heater, repeat the earlier procedure for purchasing ice cream. If it melts before you get back home, the heater works fine.
You Own an Oil Pump
Unfortunately, you probably don’t own an oil well under your oil pump. Your oil pump, like mine, is probably in your car. Your car’s lubrication system is simple. Oil held in the oil pan is pumped through the engine’s oil passages. The oil pump does the work. If it doesn’t, you’ve got a problem. Without lubricating oil, your car’s engine soon becomes expensive scrap metal. So it’s important to replace an oil pump that doesn’t work as it should before the engine is damaged.
So where the heck’s the oil pump?
Good question! On some cars, the oil pump is located on the side of the engine. On others, it’s in the oil pan (see the figure showing the lubrication system). After the oil pump is found and removed, you can repair it using a rebuild kit available from a parts store, or you can buy a new or rebuilt one.And why would you need to replace an oil pump? Because the car’s idiot light or oil gauge says oil pressure is low, suggesting that the pump isn’t working efficiently. Your car’s owner’s manual will tell you what normal operating pressure should be.
An oil pump is typically replaced following these steps:
- Check the service manual to locate the oil pump.
- If the oil pump is in the oil pan, drain the oil, remove the pan and its gasket, and then remove the pump. If the oil pump is mounted on the side of the engine block, remove the bolts holding the pump in place, and then remove the pump.
- Rebuild, repair, or replace the oil pump by following the manufacturer’s instructions.
- Replace the oil pump in the reverse order in which you removed it. If oil was drained from the oil pan, clean out any built-up sludge in the bottom of the pan, replace the gasket, and reinstall the oil pan.
You’re ready to begin pumping oil again. Well, at least your car is.