If mods want to make this a sticky or something please do. If wish to edit let me know as well. ** I don't have access to the hot keys to bold and such to make reading easier, feel free to edit for easier reading **
Major Components: Radiator, Water Pump, Thermostat, Hoses, Heater Core, Engine.
Question: "My car overheats, what's wrong?"
1. Does your car have a leak? Is it losing coolant? The BEST way to figure this out is to use a pressure tester, or have your car pressure tested. What this does it pressurises your cooling system and allows you to look for a leak. Don't forgett to look in the heater core area (coolant on passenger side floor, or smell of coolant when heater is on, fogged up windows).
If you find your leak, fix it first. If you're loosing coolant and you can't see the leak, you either A. Missed it. or B. It could be leaking internally (headgasket, radiator/trans cooler, etc.)
Please fix your leak first. Running low on coolant will cause the car to overheat, and also introduce air into the system, air pockets can cause overheating, and even cause oveheating while the guage shows correct tempurature, and ALSO not allow your fans to kick on (Coolant sensors and fan switches work off of COOLANT tempuratures, not AIR temps. In other words, if there is an air pocket at 600 degress and it's in the area of a sensor, the sensor doesn't care and recognise it).
Note: Headgaskets USUALLY go between the #2 and #3 Cylinder. If your loosing coolant and don't see it, pull the plugs and especially look at the #2 and #3 cylinders. One clue may be to compare them to the others. If one piston looks Shiny and/or Super Clean. Chances are you have a headgasket issue and the coolant/water is steam cleaning your piston. That's just one check.
Another common symptom of headgasket failure is the immediate pressurizing of the cooling system. If the coolant is FULL and you start the car with the radiator cap OFF, it will shoot out the radiator. If so, it's not good news for your headgasket.
Yet another test is a Carbon Monoxide test. Some SLOW or just starting headgasket leaks can be found with a tester that goes on your radiator, the car is started, and if carbon monoxide is in the system, the liquid will change color, if so, the headgasket is bad and allowing combustion fumes into the cooling system.
Headgaskets don't always rear they're ugly head all the time. Sometimes it's while the car is cooling down it will leak, sometimes under heavy load, etc. It's not always a "as soon as it leaks it keeps leaking" type thing. It can come and go with tempurature change in the engine. But either way, as soon as it starts to go, it needs replaced, it will not get better.
If you replace a headgasket, ALWAYS have a machine shop check it and surface if needed. If you don't have the proper surface, your just causing yourself problems in the future.
2. No leaks, my car still overheats, what's wrong?
A. Does your fan kick on?
1. NO. My fan does not kick on.
The fan on most Honda's kicks on around 190° and off between 182°-188°. Most Domistic cars fans don't kick on till about 224°.
If the fan is NOT coming on and you DON'T have a leak, you need to check Grounds, Relays, Fan, and Coolant Temp Switch, perferably in that order. Check a Honda manual on how to check some of these. There are some simple steps you can do with a multimeter.
2. YES. My fan does kick on.
Ok, so your fan is working, and you you DON'T have a coolant leak. Well it could be a headgasket right? If your not losing coolant then NO, it's not likely a headgasket.
a. A thermostat is a possibility, but haven't seen to many problems in a Honda. If you replace the t-stat (inexpensive) then make sure you get a Honda Part.
Note: Please just put a Honda T-stat in your car and knock that out of the overheating equation. NOT running a T-stat is not a good idea at all. For one, the system was DESIGNED for the t-stat to be there and working properly. Removing the stat on SOME CARS can disrupt the proper flow (not going to get into this right now, but it does happen). Not running a T-stat also causes the Engine Management to run differently. You'll use more gas, and possibly hurt power. Just don't do it.
b. Another possibility is the radiator. But it doesn't leak right? Doesn't matter. A radiator can cause overheating in 3 ways.
1. It leaks (duh
2. The fins are VERY corroded and missing. Missing fins and a half corroded away radiator does not allow it to cool the coolant properly, and YES, can cause overheating.
2. Blockage. ONE way to check for blockage is a "Infared" Temp Gun. You can check the radiator in several area's and see if there is a major difference.
Now you can STILL have flow, but blockage at the same time. Don't be misled. Partial Blockage can block MUCH of the flow of coolant, but you can still see it "flowing". Years of corrossion and "stop leak" contribute to blockage. If while taking the radiator out you notice it's EXTRA heavy, chances are it has a lot of sediment and should consider replacing. If you do, consider flushing the system well.
c. A water pump usually does not cause overheating (if not leaking) on a Honda. There are some other cars in which the Water Pump "impellers" disinagrate over time, but not usually on Jap. cars. MAJOR sediment gumming up the impellers would be the only case. I'd say darn near unseen on a Honda, but possible.
Cooling System Tips: If your car is coming close to overheating. Turn on your heater, and put the blower on full blast. Your heater core is another small radiator more or less, it can assist in cooling.
If your car goes into the red. PLEASE SHUT THE CAR OFF NOW! Don't drive your car, pull over and shut it off. Why? Because it could be something very simple, but if you keep driving while overheating, you can quickly destroy everything, YES, you can destroy just about everything depending on the extent and temp. Headgasket, head, rings, etc etc etc.
If you really care, use only Honda coolant and parts. Now many backyard hacks on hear don't have a clue, but it has been proven time and again, not just with the cooling system.
Honda Coolant for example has a much less corrosive nature than most other coolants, and last longer. There have been studies that show this. Why do you care? Because less corrossion means less eating away of the gaskets, hoses, radiator, etc. It really does make a difference in the long run.
Use a Honda T-stat as well. Don't cheap out on this.
Last Tips: I see many on HT cheap out and try to "Hack" their way to freedom. I understand some like to keep things cheap, but you usually cause more problems. Do things right, do them once, and it is THEN much easier to solve problems. This goes for the cooling system and many other aspects of the car.
The less you do things properly, the more variables and problems you introduce into the equation.
More basics to come...........
Modified by juevi at 4:11 PM 5/23/2007
Modified by juevi at 7:24 PM 5/23/2007