Suggestions I have so far.... check fuse (could it really be that simple?) check fluid levels (water and oil) TO CHECK FAN turn on AC. If fan kicks on, you know it's not a prob with fan. If it doesn't, you know it is. TO CHECK THERMOSTAT Touch each hose very carefully (they can be extremely hot). If the temperature gauge is indicating that the engine is warmed up but one hose is hot and the other is cold, the thermostat is probably stuck closed, and the coolant isn't circulating through the radiator. another way to check thermostat... Remove your radiator cap (when it is cool), then start your engine. When your engine warms up to operating temperature your thermostat should open and if your water pump is working you will see water move across the top of your radiator. The thermostat acts like a valve the lets the water flow when the engine needs to be cooler and closes when the engine needs to be warmer. IF NONE OF THE ABOVE REVEALS A CLEAR PROBLEM Fan clutch may not be working properly
If its a car, and not a truck, more than likely you have an electrical fan. It will be either the fan motor itself (especially if its a GM product) or the fan relay. Won't be a water pump or a thermostat.
I just read something online that says... "turn on the heat. If the heat comes out cool, the thermostat is stuck." This reminded me of something. One or two weeks ago, when it was cold, I tuned on the heat and it was sometimes-hot, sometimes-cold. I'm suspecting the thermostat more and more after reading that.
Its not going to be your thermostat because your vehicle wouldn't cool down when in motion or @ a stop. The electric fan is designed to come on where there is no air flow passing through the radiator (i.e. when the car is not in motion). When you are @ a stop, there is no air flow to cool down the fluid passing through the radiator tubes ..that is when the electric fan should come on. This is why you are not overheating when in motion, but are overheating when @ a stop. The fan is not coming on like it is supposed to.
I was also going to suggest the fan clutch, but it seems that you have an electric fan. I don't know anything about electric fans, so I'm not any help here. I had this exact problem years ago and it was my fan clutch. May as well try the suggestion re: starting the car (while cold....wait overnight) with the radiator cap off, let the car heat up, and see if it cycles....its an easy enough thing to do. I wouldn't think the thermostat would be the problem if it cools off while driving. As FT and codell said, it ought to be stuck either open or closed were it to fail and thus wouldn't matter a bit if you're driving or standing still. How old is your car, and thus your radiator? Have you noted whether or not you're losing coolant or anything like that? Even if you haven't noticed any stains in the driveway, its a pressurized system and may not leak until its under pressure.
hmmmm... okay... sounds like the fan or fan clutch is probably the culprit, then. I don't believe it's lost any water/coolant - haven't seen any puddles under it anywhere. When I get back to it, I'll check the level, though. it's a 1997.
It was a 10 yr old Ford engine... I was told it was a fairly common problem. But basically sealed up the gasket and the car wouldnt stall out anymore. Ofcourse that seal only lasted another month or two...
an electric fan doesn't have a "clutch" persay, but rather a switch/relay, so you can rule that out if you have a manual for your car, it should have a relay/fuse diagram and it wil show you which relay controls the fan ......you can get a new one @ Auto Zone, NAPA, etc. for less than $10 ....once you find where it goes, it takes about 5 seconds to replace im going to go with the fan motor itself ......after 10 years of turning off an on, dozens of times each time you drive, its going to eventually fail ......because it is electrical, it is a pretty common item to fail over time you can get new fans from NAPA, Auto Zone, etc. for pretty cheap and a mechanic shouldnt charge you more than 1.0 to 1.5 hours labor to install it
Thanks! Is the fan something I can install my self? (I'm quite capable of doing simple remove-and-replace work).
If you are mechanically inclined, sure. Its not complicated. Buy a repair manual online for your car (find them cheap on ebay) and just follow the directions. Cooling fan replacement should be in there. I'd plan on spending a couple of hours on it at least.
I fixed the car. I would like to thank the following users for their help: DOMINATOR, McGradySNKT, adeelsiddiqui, Fatty, Rookie, VooDooPope, Falcons Talon, codell, Lynus302, tigermission1, KingCheetah and meggoleggo Guys, it was meggoleggo who was the first person to predict the problem; it was the thermostat. First, I checked oil and fuses. No problems. Then I checked the fans by turning on the AC. They worked fine. That meant it was probably the thermostat or water pump. I figured the thermostat was the next thing to try, and something told that this is what it was. I went down to AutoZone and bought a new thermostat and gasket for $7. Had to drain the coolant from the system. Removed lower hose from radiator and unscrewed the thermostat cap. Pulled out the old thermostat and put in the new. Put it all back together. Started it up and coolant was spewing out of it; I didn't get a good seat on the thermostat. Took it apart and put it together again, focusing on getting a good seat on the thermostat. Worked great. Haven't overheated since. Total cost: $7 for parts, and a couple hours of repair time. Thanks, everybody! You saved me money!
Yeah just because it only overheats at a standstill does not rule out a coolant (waterpump, thermostat, coolant leak) problem. Most of the cars on the road wouldn;t even need coolant in most conditions and without coolant run cool except when no air is passed across them. Modern car's fans only cool the radiator they don't blow air on the engine like driving does.
