[CAR] Radiator Fans issue - im stuck! (SOLVED)

[Hawkeye1250FA]

Afternoon all,

Opening this up to the world of BCF as I have exhausted everything I can think of.

Car: Honda Civic 57 plate petrol 1.8
Problem : Overheating
Cause : Radiator fan and AC fan not kicking in when up to temp

Stuff tried so far:

1) replaced ECT2 sensor
2) replaced both relays
3) Fans kick in when I complete the circuit from the relay to ground
4) Fuses ok in engine bay
5) Fuses ok in cockpit

Based on the above - I have figured that it was the ECT2 sensor causing the problem, but when I've replaced that, and it still doesnt work - im stumped!

I'm left with two options:

1) Blocked coolant pipes causing no heated coolant to get to the sensor to trigger it
2) Electric issue / damaged wires / etc in the cabling to the ECT sensor

If anyone has any advice on how likely the above is - or if there is another simpler thing to test first, please let me know! Im not working on it again until the weekend, so just getting stuff together now.

Thanks!
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1993 RF400R - 2002 Bandit 1200 - 2012 1250 FA

[Easy-X]

What sort of situations is the overheating happening? Just stationary in traffic or even when you're moving and getting natural airflow?

Things I find helpful to check: get a Bluetooth/WiFi OBDC dongle and you can plot the temperature sensor(s) on a nice graph in the Torque app. Also, when up to temp, whack on your heater. The heater matrix is like a tiny rad that dumps some of the heat from the water system so getting no heating hints at an airlock. It's also interesting to see if turning on the heater (fan on max) makes any odds to the coolant temp.

If you're okay with auto electrics you could rig up a temporary switch and, coupled with a monitoring app, switch on the fan as you see fit. Not practical but it might help to decide whether it's a coolant flow issue or actually a coolant monitoring issue.
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Royal Enfield Continental GT 535, Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[Hawkeye1250FA]

[WD Forte]

https://honda-tech.com/how-tos/a/honda-why-wont-my-my-radiator-fan-work-377261
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bikers smell of wee

[Hawkeye1250FA]

[Copycat73]

thermostat fitted wrong way round..
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Whatever I post I have no citation and no intention of providing one..
caveat emptor

[Hawkeye1250FA]

[jaffa90]

What tells you it is overheating???????

[Hawkeye1250FA]

[Nobby the Bastard]

How many wires to the sensor? Can you bypass it?
____________________
trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Triumph Sprint ST 1050

[Hawkeye1250FA]

[Nobby the Bastard]

If he shorted out the switch (disconnect ting it and using a it of metal to the two ends of the wires) doesn't switch the fan on it's not the sensor.
____________________
trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Triumph Sprint ST 1050

[Hawkeye1250FA]

[Nobby the Bastard]

There should be a trigger wire from the control unit (this could be the sensor or it could be the ecu.)

Is there a.voltage there when the engine is hot?

The other positive on the relay will always be live when the ignition is on.
____________________
trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Triumph Sprint ST 1050

[Hawkeye1250FA]

[Nobby the Bastard]

Energise the relay by providing 12 from the battery directly to the trigger with the ignition on.

If it's easier, apply the voltage to the sensor end of the trigger wire.
____________________
trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Triumph Sprint ST 1050

[Hawkeye1250FA]

[yen_powell]

Not an iffy thermostat is it?
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Blackmail is a nasty word........but not as nasty as phlegm!
XT1200Z and a DR350 in bits

[jaffa90]

"""""""Overheats in all situations, but takes longer if I keep the revs at idling speed. But eventually gets to the red."""""

If it overheats on the move then a fan won`t make any difference.

Can air get to the rad?
Is the rad front full of crap?
Is the top hose hot first and then the rad and then the bottom hose warm last?
Any bleed valves? (air pockets)
Does the engine perform ok from cold and when heating up (thinking of a weak mixture).?
You may have to remove top & bottom hoses to check engine & rad circulation,( get the hose pipe out).

[WD Forte]

have you tried turning it off and back on again?
____________________
bikers smell of wee

[Sister Sledge]

[Hawkeye1250FA]

Ok Thanks gents,

Are you confident in that statement across all car makes and models? Ive purposely overheated the engine and then shorted the fan to run - which then brought the temps back down.

Top hose gets hot first - then lower hoses, although thinking about it, I didnt spend much time on that - so Ill re-investigate that - a blockage could be the culprit.

Dont know of any bleed valves, the only valve I know is the coolant drain under the engine which id imagine wont do the job

Can you expand on the hosepipe test for me? Not done that before but sounds fun
____________________
1993 RF400R - 2002 Bandit 1200 - 2012 1250 FA

[Nobby the Bastard]

If the fan is cooling it down then that's airflow through the radiator. The coolant system is doing its job.

I'm inclined to think it's actually the relay.

Is it a normal 4 prong one? For the sake of 6 quid theres an easy test....

https://www.halfords.com/webapp/wcs/stores/servlet/ProductMobileDisplay?catalogId=10151&langId=-1&categoryId=310504&productId=756415&storeId=10001
____________________
trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Triumph Sprint ST 1050

[Hawkeye1250FA]

[Hawkeye1250FA]

Another thing to note is the air con fan never kicks in either, which is why im being mentally led down the dodgy elecrics route.
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1993 RF400R - 2002 Bandit 1200 - 2012 1250 FA