I'll turn this into kind of a query so it'll stay in the Q&A forum with all the overheating posts.
If you're running hot and looking for some answers, there are some simple things you can do on your own.
I'm not some all-knowing oracle who can solve the world's cooling problems but with basic info I (as well as many others here) can knock out 90% of them quickly with minimal time and money.
Number one, beyond any question, is to get a temp gun. Period. End of sentence.
Harbor Freight has them on sale for $37.
http://www.harborfreight.com/infrared-thermometer-with-laser-targeting-non-contact-69465.htmlThose things work great. Sure, they may be off a degree or two but who cares? You're looking for big swings in temperature and they will get the job done.
If you don't have one you obviously don't want to know why your car is overheating. Get one. Now. We'll wait for you. This thread should still be around when you get back from the store.
Don't have overheating problems? Go get one anyway.
If you have real temperatures of different parts of the cooling system it's really easy to track down any problems. Without those temps you're just guessing.
Use the temp gun to check the radiator temperatures. if your cooling system is working properly you will have about a 30 degree difference between the radiator inlet and outlet. If that isn't the case you have a problem up front.
Scan the radiator across the core. If there are cold spots you know the radiator is plugged and needs attention. Obviously, the radiator will be cooler where the fan is drawing air. If the fan clutch is slipping or the fan is too weak then you will not see a substantial drop in temperature in front of the fan.
Here's a BIG hint: A proper shroud will pull air from all parts of the radiator, not just the bit right in front of the fan. That's why shrouds are important.
You can use the temp gun on the temperature sending unit to confirm the gauge reading.
It can also spot colder spots on the engine if you have a misfire or dead hole. The temp will be cooler on that part of the exhaust manifold too.
You can shoot the cylinder heads to see if one side is cooler than the other. That would indicate problems inside the engine.
Trouble with the A/C? You can check air temperatures at the registers as well as line temperatures under the hood.
Don't have a candy thermometer? You can use the temp gun to monitor you cooking oil when frying hush puppies.
Back to trouble shooting...
If the temperature of the hoses is drastically lower than the temperature of the block and heads then you're not moving water. Check the lower hose to make sure it's not getting sucked closed when the engine is revved. Sometimes it's hard to see so you need to lay hands on it. Just don't get your arm caught in the belts or fan.
If the upper hose is drastically cooler than the thermostat housing and top of the water pump you know the thermostat isn't opening.
Engines without thermostats will sometimes move coolant too quickly. That doesn't allow the coolant to stay in the radiator long enough to lose temperature. You can spot that when the radiator temps drop smoothly across the radiator but don't change by more than 15 degrees or so.
If you want to know why something doesn't work you need to find out what part isn't working. When that's a cooling system you must know the temperatures you're dealing with. Without that basic info it's all guesswork.
Have a problem? Want help?
1) Get a temp gun.
2) Get numbers.
3) Get back with us.
Now, to form some sort of question to keep this in the appropriate forum...
What other tools do you guys use to diagnose cooling problems?
