I just went out to lunch. Not far and while it is a hot day, not the worst. I got coolant over temp and 260 degrees. I had to limp back to work, coasting and getting as much air as i could flowing. It did come down and of course fans are running. I dont see any leaks right now and will let cool off for a a while. Any suggestions where to go? This is first time ever showing this. Thermostat? Water pump? I do have fuild in over flow. Thanks

 

I'd start with checking to make sure there isn't anything blocking air to your radiator or a/c condenser. Then move on to your hoses and make sure they are intact. Move on to your the rest of the engine bay and check for any coolant leaks.

 

Thanks, I've looked and no leaks that I can see so far. It just seemed to go all of the sudden. Really went bad (fans kicking in) right before I got into a drive thru line, and then just climbed. Almost took off without food. I was moveing 35 mph for a 2 miles or so before I turnned into line. I had made one stop, turnned car off, to run into a store (2 mins) then back out for this 2 mile drive to the drive thru. Didn't notice a thing until the fans started going and then checking gauages.

I've gone back out to car and to check over flow box but it's way too hot to open right now. All hoses look good. I don't see any leaks. When I start to undo the cap on over flow box, it's still to hot. It starts to boil a bit so I'm Letting it sit for now. I started the car and don't hear any wierd or bad rattling. 85k miles on stock 2002

Something went. This car was not running more than 15 mins before this happened. The car was great this mornings drive to work, but I did have higher speeds and little traffic to deal with. No signs of any problems before this. I guess something went all at once, and that's the way it happens sometime.

 

Is the hose going to the water pump hot? If not then you have a stuck tstat or bad water pump. If it is hot, take a towel or rag and squeeze the hose if the car is still hot. Can you hear the antifreeze swish around in the tank? When you get off work check that same hose. If it's sucked in then you have a radiator cap that needs replaced. Turn on the heat if the car is still hot. Is it hot or cold?

 

Thanks. Im at shop now. On drive down in slow traffic it jiumped up. Then i was able to run at 60mph and it cooled to 190 and stayed normal. When i got back in slow traffic it went to 220. And even cooled a little as traffic moved again. So now its in the hands of the pros. We'll see soon. I hope. Its just stst.

 

Sounds like a bad thermostat to me... Mine had similar symptoms before i swapped it out.

 

 

Shop pro thinks it's a bad fan. I'm going to start my search now, but I'm not sure if the fans are suppose to work they way he described. But if anyone wants to joint in, please do. I know I had one fan turning when it started over heating, very noticeable, like high speed fan. I also know that one fan runs when A/C is on and speeds are less than 35 (i thought). I did not see both fans running. The fan that is not working (so said tech) is the driver's side (LHS) fan. So far as I know he did not check fuse/relay for that fan. I think there should be one. RHS side fan runs with A/C on, but temps were about 220 when I checked that. LHS was not running at 220. Anyway I'm going to search for cooling system and fan operation on here. What is stock stat temp?



I was just reading another thread. Someone suggested jumping the fan relays to check fan operation. Anyone know how that's done..

 

Here you go

Fan 1 on temp 226
Fan 1 off temp 219
Fan 1 enable 30mph
Fan 1 disable 35 mph
Fan 1 on temp A/C on 185

Fan 2 on temp 235
Fan 2 off temp 227

 

Dont know how it posted twice..

 

I hope you, or they, checked to see if a bag or debris got sucked up into the area between the radiator and condenser. Happens all the time.

 

Thanks.

I take it fan 1 is LHS and fan 2 is RHS fan. RHS is working. LHS side may not be working. It's raining now and car is cooling off. I'll go play with it some later.

So fan 1 comes on with A/C? Right now only fan 2 comes on with A/C. temps around 230, best I could tell from outside car.

I was looking at schematics from another thread. While fan1 control is separate (low fan) from fan2 (high fan), the current flow for fan1 is through the fan, then through UN-energized coolfan3 relay (44), through fan2, to GND. This would indicate that relay 44 has to be good also, and both fans operate with low fans control signal. Once the highfan control is set, fan2 is turned on the current from coolfan2 relay flows through fan2 and fan1 current is taken direct to ground (via coolfan3 relay) and no longer going through fan2. Would both fans be on at this time, with lowfan control signal?

I tried to copy schematic to this thread. No luck.

Just so more info is on this thread. fan1 or coolfan1, fuse is fuse 49, relay is 45.

fan 2 has two fuses and relays associated with it. One set called coolfan2 and the other called coolfan3. coolfan2, fuse is 46, relay 43.

coolfan3, fuse is 14, relay 44.

Here's a cooling fan schematic.

Click the image to open in full size.

second try, idk

 

Thanks. I was typing up my last post and trying to post the schematics while you both responded.

The way it looks to me is fan1's (RHS FAN) current has to flow through fan2 motor. This to me means both fans are on with the low fan control signal at PCM. High fan looks like only one fan runs, fan2 (LHS FAN). Does this sound right?


Yep, time to pull and replace relays and fuses. Anyone know/want to post the relay part number?
Thanks

 

So if both fans operate in low fan and high fan mode (fan1/fan2 above).

Then the only way that (low fan) cooling fan left, wont work is an open starting from coolfan1 fuse, relay, cooling fan left, coolfan3 relay, all the way through cooling fan right to GND. low fan control allows 30 amps to run both fans. High fan control allows 30 amps to each fan, if low fan control is still set at PCM.

If cooling fan right works then I can eliminate that fan as open. Now I only have to verify/find open in coolfan1 circuits, coolfan3 circuits, and cooling fan left.

 

I forgot. First, Thanks Bill for posting info/schematics and help. Second, thanks everyone for help too

I did check for debris in radiator, nothing big, got some bugs. I can clean that up.

 

Thanks.... What a much better way to describe the operation than my pitiful attempt. I should know better. I do understand the terms series and parallel.

The only thing I did not know, was if the coolfan1 relay would be energized in addition to the high fan mode, but I assumed it did. Thus operating both fans (in parallel) with their own 12 volt/30 amp circuit. I will have to do this tomorrow, as things did not work out for this tonight. I will get a few relays and fuses tomorrow and start the plug n' play. I'll get a voltmeter too. Thanks for your input and help.

 

It took me a while but I can verify that both fans work. In Low fan mode both seem to be turning. If the schematic is true about LHfan and RHfan, then I can see and hear my RHfan go into high and low modes. The LHfan (drivers side), it's just too damn hard to see it turning, too much stuff in the way.

So I got some long cardboard and managed to get it into the fan (LHfan) and feel/hear the turning fan hit the cardboard. But I only got this done in low fan mode. Man, it's hot over this motor. So I think that fan is OK. Wife suggested I use my fingers. hehehe Sure, go ahead honey.

I have checked fuses and swapped relays 45 and 43. Same conditions above, so they are OK. Or just pulling and resetting fixed it. I assume that 44 is working. There could be a problem with that relay, but haven't totally verified yet. If it is, I would loose the LHfan in parallel or high fan mode. I ran the car long enough to think that it would over heat like yesterday, but it has stayed rather cool so far. I gotta go to work. I hope it stays together. Thanks for help and explanations on operation.

So I still wonder why the big jump yesterday and if it's a sticky stat problem.

 

Nice info...finally somebody.with a wonderful technical explaination

 

Finally?
This information has been readily available on this forum and posted hundreds of times since 2001.

 

Doesn't hurt to repost or revive a thread, especially good info. It's not like there is a lack of storage space on the 'ol CF forum website.