radiator fan not running

[jspec civic]

Hi guys,

i have notice on my civic my rad fan does not run when temperature is reached. I have done some trouble shooting. checked fuses under the dash and fuse at the bay all ok. swaped relay with the next one beside it & fan doesnt come on. I have flushed all the coolant and also tested the thermostat and it opens fine at required temperature. The I unplug the thermoswitch and plug a pin between the contacts and fan runs with ignition on so there for my fan motor is fine. What I found out was that the bottom rad hose isn't hot atfer the car has been idling for awhile, temp gauge sits below half.

Does this mean that I have a fault switch and a bad thermostat (not opening to circulate the coolant)?

Thnks

[flipfire]

Exactly what temperature has it reached? I changed the coolant on my EK and it was quite hard to get the fan to come on even after a hard drive. The needle just sat below the halfway mark and wouldnt go any higher.

If your thermostat was stuck at the closed position, your engine would overheat eventually. If it was stuck open, your temp guage would drop when your on a highway.

Unscrew the fan switch out, see if theres a build up of crud on it.

[jspec civic]

there were a little bit around the threads of the switch...i have let the motor run for over 10mins with heater on...

[flipfire]

Close the heater switch off, ur only supposed to open it when changing coolant so everything gets flushed out.

Thats why its not building up any heat. Heater core dissipates it out of the coolant.


there were a little bit around the threads of the switch...i have let the motor run for over 10mins with heater on...

Did you unscrew the switch from the engine block and looked?

[jspec civic]

i had a look at the switch when i was testing the thermostat, i didnt unscrewed the switch...like i said thermostat opened fine when i heated it up in hot water. any more inputs any1???

[GenesisEG]

Well, from the little I understand about this, it would seem that the thermostat is not reaching the required temperature to close the switch.

Flipfire might be right, the temperature might not be high enough?

Try leaving the car running without the heater going. The heater runs the coolant through the heater core and helps to reduce engine temperature. It simply acts like a second radiator. That too was mentioned by Flipfire.

They would be my first two ports of call. If the coolant simply isn't reaching the necessary temperature, then you have no problem. Has your car overheated yet?

[90LAN]

just run 12 volts to fan and see if it turns on

if it doesnt you have busted fan motor

[GenesisEG]

The I unplug the thermoswitch and plug a pin between the contacts and fan runs with ignition on so there for my fan motor is fine.

I think the fan works.

[Bludger]

dude, its trial and error.

you have figured out that the fan motor works.

so eliminate what is in between.

you have mentioned you checked everything exept the fan switch.

change to new one and see how you go.

[jspec civic]

i would like to know that if its the switch than i would look into getting one..what does cold bottom hose mean? thermostat not opening right?

car overheated two weeks ago due to no coolant..fan doesnt work after coolant has been flushed..lan fan motor works for sure..im sure the left the car idling for ages...i will try again..

[GenesisEG]

It could be operating properly now and the engine is simply not reaching the temperature required to trigger the thermostat.

The only problem I can think of that might be causing a lack of coolant circulation is a busted water pump. Did you check the operation of the pump? Running it dry might have damaged the pump, meaning the coolant is not circulating, meaning there is no heated coolant running past the thermostat, or through the hoses.

I'm no mechanic, but maybe you should test the pump.

[jspec civic]

just an update..i replaced the thermostat n switch with new ones...when i start the car the the top hose gets hot 1st and after approx 5mins the bottom gets hot..they both very hot after awhile..fan isnt coming on...what next???

[markismaximus]

just an update..i replaced the thermostat n switch with new ones...when i start the car the the top hose gets hot 1st and after approx 5mins the bottom gets hot..they both very hot after awhile..fan isnt coming on...what next???

fans wont turn on after starting a cold car and running it for 5 mins. go for a 15-20min drive. When you stop driving let it idle for 5 mins, the fans should come on

[GenesisEG]

Do you read the responses posted here?

[jspec civic]

Do you read the responses posted here?you refering to me?

had car idle for ages mate..

[ekcoupe]

I have the same problem, my fan ain't turning on, i worked out my coolant temp sensor was broken so getting that tomorrow an hopefully that fixes it, maybe that could be your problem aswell?

[flipfire]

?

Isnt coolant temp sensor just for the temp guage in the cluster?

Its the fan switch & thermostat that would make a difference

[ekcoupe]

that's what i thought aswell, but it was never plugged in an the temp guage was still working,

took it to an auto electrician an said that could most probably be your problem.

[GenesisEG]

Yes, I was referring to you.

I've already asked several questions and given you a couple of possibilities that seem to have fallen into oblivion.

Does the car overheat? That is, has your temperature gauge hit the red zone and steam come barrelling out of your radiator?

If you are going to post a question, you need to pay attention and read the responses. It's quite possible that you have no problem, and that the reason the fan isn't turning on is because the engine isn't getting hot enough. If that's the case, you could spend thousands of dollars replacing parts that are working just fine. Confirm that you have a problem before you try to fix it.

The only time your car has overheated so far, judging by the posts you have made, is the time you let the radiator run dry. The biggest risk of damage in this case is the water pump. If the car has not overheated again since then, it's likely that you got lucky and no damage has occurred. If the car is overheating, the first place I'd be looking is the water pump.

Please go and check these things and come back to me with a response. I want to know if you can get your gauge to get into the red (drive hard for 30 minutes), and once you have achieved that, we can discuss the possibilities.

[jspec civic]

Gauge not hitting the red zone doesn’t mean the car is not going to over heat does it (can be a faulty gauge) Wouldn’t you think driving it hard could cause more damage that’s already been made. 30mins it’s a long time. I would have to think about that one, but diffinetly will drive it. I will have a look at the water pump for any leaks. thnks

[markismaximus]

Gauge not hitting the red zone doesn’t mean the car is not going to over heat does it (can be a faulty gauge)

test the gauge then, easy as. Takes about 5 mins.

http://i225.photobucket.com/albums/dd121/mx83cressida/Honda%20FSM%20Pages/DC2.jpg

[mr180sx]

Do you have a stock radiator or have you upgraded

[GenesisEG]

Gauge not hitting the red zone doesn’t mean the car is not going to over heat does it (can be a faulty gauge) Wouldn’t you think driving it hard could cause more damage that’s already been made.

Faulty gauge would be unlikely to work at all. If it's going up to the middle and sitting there, there's a good chance that your engine is running at optimum temperature.

Driving it hard may cause damage, indeed, but letting it sit there idling may not be raising the temperature enough to cause the fan to cut in.


30mins it’s a long time. I would have to think about that one, but diffinetly will drive it. I will have a look at the water pump for any leaks. thnks

I'm not so concerned about leaks, I'm more concerned about the pump not pumping at all. Pump failure means a total lack of coolant circulation, meaning that the water won't be flowing through the pipes at all, which would explain the lack of heat you were experiencing earlier. I had a pump go on me once, steam started coming out of the radiator within minutes of driving. Trust me, if the engine is overheating, you can tell.

The reason I am getting you to check these things first, is because this is the basic principle of fault finding. It's something everyone should learn to do.

First, you need to establish that you have a problem. Far too many people jump up and down about a fault before actually establishing that there is one. I once got called up to Coffs Harbour from Sydney for an emergency service call on a building access control system. Apparently the main entrance into the building had a proximity card reader that was not working. It took me 7 hours to drive there, and I had to stay overnight, only to find out that the card reader worked fine, and it was actually the door that had bowed due to the moisture in the air, causing it to jam. Make sure that you have a problem before you get worked up about it.

Second, once you have established that you have a problem, sit down and work out exactly what the problem is, and list all the possible causes.

Third, go through the list of possible causes and rearrange them in order of easiest to test through to hardest to test.

Once you have this rearranged list, work your way through testing it. The easiest possibilities may not always be the most likely, but fault finding is a process of elimination, and the best way to solve a problem is to eliminate the simple things first. If a circuit in your house is constantly tripping off, you don't rewire your house immediately, you check to make sure that you don't have any faulty appliances plugged in. It's far easier to remove corded appliances than it is to rewire a house. It may well be that the wiring is faulty, but if you rewire your house and the problem persists, you've gone through alot of effort and expense for nothing. The same logic goes for automotive fault finding.

So, make sure that you have an overheating problem. If there's no problem, the reason for the fan not activating is simple; the ECU hasn't asked it to. The fan will only come on to help cool the car, and only then if it needs to be cooled. Don't be so quick to assume that because you haven't seen the fan operating that there's something wrong.

If you are able to establish that there's a problem with the car, then work out what could be causing it. Rearrange that list and start testing components, starting from the most simple and working your way through.

Don't start replacing parts willy-nilly in the hopes you'll fix something. You'll end up spending an absolute fortune, and you may just find out in the end that you never had a problem to begin with. DIY repairs are a matter of patience and thought, if you just want to throw money at your car, take it to an auto-electrician and let him do the hard work. It's quicker and easier to get someone else to do the work, but you won't feel the satisfaction that you do with DIY repairs, and you won't learn a thing about your car.

I hope I haven't offended, but I'm trying to do more than just help you fix your car. I'm trying to show you, and whoever else may be reading, how to go about fixing anything. There's a process, and it can be applied to anything, anything at all. I really hope that what I've posted helps you to solve your problem. I think you'll be much more satisfied if you fix it using your (hopefully) newly acquired problem solving skills than you would if someone gave you the answer or if you threw a wad of cash at it.

[najdi]

have a similiar problem to

[jspec civic]

Do you have a stock radiator or have you upgradedi'm running stock..

thanks GenesisEG...
i ran the car yesterday night..had it on idling for 30mins and than took it for a quick ride..steped on it abit. when i got back there isn't any coolant left in the reservior tank (no over heat). Before i check the water pump, will I be able to see any leaks near the timing belt cover without taking the timing belt cover off to check the water pump? and how do i tell if i got a block rad?

[flipfire]

Its normal for it to suck coolant from the reservoir after a coolant change. If you didnt bleed it 100% then theres some air pockets left in the system and that goes away eventually and gets replaced by more coolant.

To be honest your engine sounds fine man, its not overheating or playing up. If your gauge isnt going past half way then theres no reason for the fan to kick in. If your pump or radiator was the problem it would overheat.

[markismaximus]

To be honest your engine sounds fine man, its not overheating or playing up. If your gauge isnt going past half way then theres no reason for the fan to kick in. If your pump or radiator was the problem it would overheat.

Agree with this too

[GenesisEG]

Try topping up the reservoir. If it keeps dropping, there's a possible leak, but just top it up and see what happens.

I think that if the water pump had fallen over, you would have noticed it. The car would have overheated very quickly if the pump had seized up, because the coolant would not have been pushed through the radiator at all. The same would be true if the radiator was blocked.

I don't think your car is malfunctioning, I think it just runs cool enough that it doesn't need the fan to moderate the engine temperature.

[markismaximus]

The car would have overheated very quickly if the pump had seized up, because the coolant would not have been pushed through the radiator at all.

if the water pump seized the timing belt would snap.

[GenesisEG]

Learn something new every day!

Please forgive me, I know nothing of the actual operation of specific mechanical parts. All of my problem solving is based on logic with a very small degree of experience with faults I have encountered in my own cars.

I had a Commodore that overheated once, turned out to be a faulty pump. Perhaps it didn't seize, or perhaps the timing belt did not drive it, I was just applying it to this problem.

I'm bound to make mistakes sooner or later given that I'm operating purely from my own imagination. Seem to solve enough problems to justify it though.

[90LAN]

blocked radiator ?
what colant are you running ?

a normal operating temp gauge on a honda temp gauge is not half
its more like 3/4 under the half way mark pointing down

try turning your car ac on no need to go for drives
fan will come on quicker

i believe he is running a oem ek9 radiator

[jspec civic]

the only thing i have checked is the water pump...GensisEg u might be right car havnt over heated since.

Lan, i bought 50/50 antifreeze castrol coolant. How do I tell u rad is blocked?

[Bludger]

the only thing i have checked is the water pump...GensisEg u might be right car havnt over heated since.

Lan, i bought 50/50 antifreeze castrol coolant. How do I tell u rad is blocked?
go get it tested at radiator specialist.

pretty cheap.

[90LAN]

use honda coolant
i never had any issues with this stuff

[beeza]

Timmy just had this same problem.

We just ordered a 2 wire sensor,sits next to where the thermostat is on his b16.

The sensor sends the coolant temp signals to the ecu which in turn will activate the radiator fan.

There's another 1 wire sensor for the temp guage next to the oil filter.


We ordered the sensor from 'efi global' @ Burleigh.

Not sure if that's the cause but the sensor shows no resistance at all when tested with the multimeter.

Hope that helps..

[jspec civic]

UPDATE...yesterday i decided to have the car idling again but this time i had the car on for over 40mins with the rad cap off. this got rid off all my bubbles in the coolant system, finely the fan came on but not for long (30sec)..and than 10mins later fan came back on again..with the rad cap on fan came on too..i think i dont have any leaks..so i think the car is running normal. but this morning I checkd the res tank ans it was empty. Whats wrong this time?

[ekcoupe]

Don't think you have the same problem as me (beeza posted) because your fan is coming on.

Go to your mechanic and ask if they can do a pressure test on your car if you haven't already, That will find any leaks if there is any...

[jspec civic]

getting compression test and rad pressure test tomorrow..hope every is fine

[jspec civic]

update....car is running normal...done the rad pressure test and theres no leaks...coolant in res tank is not empty now..i mustd off have bubbles in the system and the coolant probably replaced it.


thanks for everyones input...CASE CLOSED!!!!! ;)

[GenesisEG]

Good to hear, glad it's fixed.

[beeza]

Alll-righty then! :)

[Sexc86]

Sorry to hijack... Is your radiator fan suppose to come on initially when you second click your ignition? (just for a few secs)