| Overheated Car Engine |
From "Ask DIY"
episode ADI-408 |
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Overheating is a common automotive problem. DIY's automotive expert Trisha Hessinger addresses some of the common questions that pertain to engine overheating. First, it's important to check your temperature gauge often, and be familiar with where the needle typically rests when the car is running under normal condition. Q: What should I do when my car overheats? A: If your temperature gauge starts approaching the red zone (figure A), you may have an engine-overheating problem. One thing you might try is to turn your car's heater on all the way, with the blower on full-blast (figure B). Obviously, if it's a hot day, you'll need to roll down the windows when you do this. The operating heater pulls hot air away from the engine, and may help cool the engine somewhat. You'll still want to have your engine and radiator checked at a service station to determine if you're low on coolant, or if there's another problem. If the needle on the temperature gauge does not begin to go back down, pull over right away. Don't wait until the needle reaches the red zone. Serious overheating can cause permanent engine damage.
Q: What causes a car to overheat? A: Overheating can be caused by driving in extremely hot conditions, but more often it's due to inadequate coolant in the engine cooling system. Check the level at the coolant recovery tank (figure C). Marks on the side of the tank indicate where the level should be when the engine is hot or when it is cold.
If your coolant is low, you'll need to top it off with a 50/50 mix of coolant (figure D) and water. Important Safety Alert: Do NOT open the radiator cap (figure E) to check the coolant on a car that's been running. The cooling system is pressurized, and opening the radiator cap could allow steam and hot fluid to escape suddenly and cause burns or injury.
Another area to check is the radiator hoses and connections. The hoses (figure F) should be supple and pliable, and there should be no cracks or leaks. Clamps should be tight, and connections should be in good condition. If your hoses or clamps are leaking, worn out or damaged, you'll need to replace them or have them replaced at a service center.
One more place to check is the thermostat (figure G), which is located at the engine and connects to the upper radiator hose. The thermostat regulates the flow of coolant between the engine and radiator. If your thermostat has gone bad, the cooling system will not operate properly, and the engine can overheat.
Q: How do I replace a thermostat? A: Replacing a thermostat is not that difficult, and if you're at all mechanically inclined, you can do it yourself. Following are the steps and safety precautions. Safety Alert: Disconnect the negative battery cable before you begin work. Safety Alert: Always wear safety glasses or goggles when working on engines, and particularly when working with batteries and the cooling system. Safety Alert: Coolant is toxic to humans and animals. Dispose of it responsibly, and keep it away from pets and children.
- To begin work on the thermostat, you may first need to remove the air filter and air-filter housing.
- Loosen the hose-clamp and disconnect the radiator hose from the thermostat housing (figure H). Some coolant may drip out when you disconnect the hose, so place a pan below to catch the coolant for proper disposal.
- With the radiator hose disconnected, loosen the three bolts (figure I) that hold the thermostat housing in place.
- Carefully lift out the thermostat assembly, and remove the old thermostat from the housing (figure J). Note the orientation of the old thermostat before removing it. You'll need to install the new thermostat so that it's facing in the same direction.
- Use a scraper (figure K) and some steel wool to remove any residue on the housing left by the old gasket.
- Use steel wool and rag to clean any residue from the corresponding surface on the engine block (figure L). Avoid letting any particles or residue get fall down into the engine.
- Install the new gasket on the thermostat housing, and install the new thermostat (figure M) making certain that it is oriented in the proper direction.
- With the new thermostat and gasket in place, re-install thermostat assembly onto the engine block (figure N), reconnect the radiator hose and tighten the clamp. Avoid over-tightening the clamp.
Remember, it's important to see to an overheating engine right away. Ignoring the problem could lead to a cracked engine block.
RESOURCES :
The Complete Idiot's Guide to Trouble-Free Car Care
Author: Dan Ramsey
ISBN: 0028635833
Alpha Books
How Cars Work
Author: Tom Newton
ISBN: 0966862309
Publisher: Black Apple Press
Auto Repair for Dummies
Author: Deanna Sclar
ISBN: 0764550896
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