overheating issues, but only at idle

[greddy339]

has anyone tried turning the fans by hand with car off of course to see if the fans are seized up or somehow being binded up?

[Omnistryder]

I had this problem constantly in the summer because when I installed my 4-1 header, that involved me removing the OEM exhaust header and heatshield and my new headers have semi melted my fan on the belt side. it still operates but with that heat shield gone... all the heat transfer from the exhaust is crazy hot.

[lduran]

I have a short header and have had it since 2003. I haven't had this problem until recently though.

[dc_johnson45]

lduran - I'm having a very similar problem with my '02 ZX3 2.0L Zetec. I've replaced the low speed fan relays - fans seem to be kicking on correctly, still heats up.

I replaced the water pump with a stock Ford pump - this helped significantly, but it will still heat up.

Thermostat has been replaced, coolant flushed, etc.

It's still happening, and I'm a bit stuck as to why.. I'm going to try replacing the Cylinder Head Temp sensor, but I'm kind of doubting this is the issue - when I put the dash into diagnostic mode it reports temps.

I'm stuck and have little else to replace other than pulling out the entire radiator!

[lduran]

I had the coolant temp sensor replaced again, in case the first one was faulty. I did notice that the coolant overflow tank has a hairline crack and is seeping coolant. I have ordered a new one from Mike (b16sir). Not sure if this could be contributing to my ordeal. The car has not over heated this week, but I have been using the defroster a great deal.

[penguin]

> has anyone tried turning the fans by hand with car off of course

That's the way to see if the fan motor bearing etc. is frozen... but... be VERY careful!!

I'm not sure about the Focus, but a lot of new cars can start their fans with the engine off and the key removed if the temperature sensor is hot enough, e.g., if hotter coolant moves up after the engine is off, the fans can start. I'd hate to have my fingers in there when it started.

So... don't do it immediately after shutting the engine down, or disconnect the battery to be sure.

[whynotthinkwhynot]

^ Been there done that, you'll be fine, maybe a blood bruise at worst- it's a plastic blade, and it's not like the motor is all that powerful. Once it's spinning it would have some force behind it though.

[greddy339]

i didn't mean try to turn the fans right after shutting off the car! hehe...i meant to say but didn't was to wait til the mourning and then try to turn them by hand.

[lduran]

I replaced the coolant tank and lid because I noticed that there was a very small amount of coolant coming from the side of the tank. When I took it off, I found a small hairline crack. The car has not overheated since then, but today, towards the end of my commute, I noticed the temp gauge move a bit. When I got home, I place the car in park and opened the hood. The coolant level was fine, but I saw two small bubbles form in the tank (like it was going to start boiling). I went back and looked at the gauge and it had moved just a little bit towards hot, but not much. I turned the car off and felt all three hoses that come off the over flow tank and they were all scorching hot. Also, the tanks itself was pretty hot. Does anyone have any more ideas? I would hate to change out the spark plugs only to find out that it still does it. I like my car and would love to keep it, especially since it is paid for, but after $700 in repair bills in the last two months, I have to know when to throw in the towel. Any help would be greatly appreciated.

[lduran]

I just went out and got a water wetter to see if it helps. I know this is just like putting a band aid on the problem, but if I can't find the culprit, I am not sure what to else to do. I turned on the defroster for 5 minutes and ran it to try to circulate the water wetter and to see if the car would get hot. The fan kicked on around 4-5 times during this period. Is this a normal event? I know it is supposed to kick on, but I did not think it would happen so frequently. The car had been off for about 2.5 hours before this.

[pliznyk]

ive had the same overheating problem, it seemed to help when i key banged while driving, the temp would drop right back down after starting it back up. then I found that my fuse was blown, so i changed that and checked for the problem that could cause the fuse to blow, finding that the wiring to the fans had been melted by the header, i pulled the whole harness and began to seperate and repair the wires. ive hard wired my fans and they do work but im yet to hear them kick on on thier own. i got the wires hooked back up, and still nothing. i have noticed though that when my car first starts overheating and i check out the coolant im a little below minimum, i fill it and then im good for another week. as long as i add water once a week keeping the tank full, to the max line. i have no problems. im gonna try changing out the coolant cap, that makes sense to me cause ive had similar problems with older vehicles and thats all it was is the radiator cap. i also need to check the relay. hope ive helped someone get further in thier own diagnostics, you've all helped me. ill keep you informed as i progress.

[whynotthinkwhynot]

Originally Posted by lduran

I replaced the coolant tank and lid because I noticed that there was a very small amount of coolant coming from the side of the tank. When I took it off, I found a small hairline crack. The car has not overheated since then, but today, towards the end of my commute, I noticed the temp gauge move a bit. When I got home, I place the car in park and opened the hood. The coolant level was fine, but I saw two small bubbles form in the tank (like it was going to start boiling). I went back and looked at the gauge and it had moved just a little bit towards hot, but not much. I turned the car off and felt all three hoses that come off the over flow tank and they were all scorching hot. Also, the tanks itself was pretty hot. Does anyone have any more ideas? I would hate to change out the spark plugs only to find out that it still does it. I like my car and would love to keep it, especially since it is paid for, but after $700 in repair bills in the last two months, I have to know when to throw in the towel. Any help would be greatly appreciate.

Darn, I haven't checked to see if I mentioned that rare problem or not, but a leak from the coolant fill tank or the fill tank cap will cause you to over heat. That's one of the first things I check for weird problems.

The spark plug crack is a VERY RARE problem- one in a million, so don't be surprised if it's not your problem.

Have you flushed your radiator yourself? It's really not hard, all you have to do is remove the upper and lower hose, then use a garden hose to force water through the radiator until it is no longer full of rust. Reverse flushing is simply putting the garden hose on the lower radiator hose and trying to push enough water backwards to come out the top.

A radiator shop can pressure test your radiator for you and bench flush it, but you'll have to remove it. As far as a mechanic shop, they are going to do basically what I wrote about as removing the radiator to bench flush it would be too much labor.