Direct connection radiator fan is harmful

[Xulfiqar]

But the socket for radiator fan is with two wires, and if connect these two wires, fan goes OFF. Thereare two temperature switches, one on the thermostat housing and flange, and other in head near waterbody. The manual say these two are single wire gauges, and fan switch is a two wired thing.
BTW, she has a 2A engine (with 8 valves)

its the same classic toyota wiring system, the radiator fan relay operates backwards, meaning that when it switches off the fan runs.

The 2 wire switch has 2 wires in it one ground (earth) and one signal to the relay, when the switch heats up the connection disconnects from ground, switches the relay off and the fan runs.

more easy is

relay on = fan not running
relay off = fan running

the relay is in the fuse box and is identified by its odd shape. If your fan switches off when you short the wires the system is working correctly. If the fan does not operate when the engine temp gauge reads half - replace the sensor. (it does not go bad often, its very sturdy)

later toyotas used the exact same system with the only difference being the sensor wires, the older ones had 2 and the later ones had 1 the sensor itself takes ground from the engine block in the later ones while ground is supplied via a wire in the early ones.

the relay is switched on when the ignition is switched on, if you are wondering why the fan does not all the time because it activates when the relay is switched off, the relay routed power is supplied by the main relay which routes all power to the fuse box when the ignition is switched on. This main relay can play tricks with you as it grounds all output circuits when it switches off.

anyway - just thought that you might need this information when you start troubleshooting

[afarooqi]

its the same classic toyota wiring system, the radiator fan relay operates backwards, meaning that when it switches off the fan runs.

The 2 wire switch has 2 wires in it one ground (earth) and one signal to the relay, when the switch heats up the connection disconnects from ground, switches the relay off and the fan runs.

more easy is

relay on = fan not running
relay off = fan running

the relay is in the fuse box and is identified by its odd shape. If your fan switches off when you short the wires the system is working correctly. If the fan does not operate when the engine temp gauge reads half - replace the sensor. (it does not go bad often, its very sturdy)

later toyotas used the exact same system with the only difference being the sensor wires, the older ones had 2 and the later ones had 1 the sensor itself takes ground from the engine block in the later ones while ground is supplied via a wire in the early ones.

the relay is switched on when the ignition is switched on, if you are wondering why the fan does not all the time because it activates when the relay is switched off, the relay routed power is supplied by the main relay which routes all power to the fuse box when the ignition is switched on. This main relay can play tricks with you as it grounds all output circuits when it switches off.

anyway - just thought that you might need this information when you start troubleshooting

Xulfiqar bhai,

Its an excellent explanation of electrics for the fan working. But I want to know that where is this thermo-switch installed. bcuz someone has previously removed the switch. Is it on the housing in which thermostat is installed or somewhere else? That is the question.

Rest of the wiring is already sorted out and it is working. Only have to install switch and hookit up to wires to get the things done. Waiting for your reply.

Please check the picture, I found it over internet. Circled thing is the thermostat housing, and it has a temparature gauge as well. Question: where is the switch for fan is installed?

[PKTUN]

ap ki gari kon si hai ?

[afarooqi]

ap ki gari kon si hai ?

Corolla 1984 (AE80)

The above mentioned pic is not of my car, but it is same model.

[Xulfiqar]

the picture shows the radiator fan thermoswitch in the red circle - but it seems like a single wire version.

[MoizIrfan]

the hose pipe seems to be of very good quality

[usmanulamin]

can anyone plz shorter the whole story written by the poster ... simply plz tell the drawback of doing the direct radiator fan ...

[imran2d]

The following are the problems summarized keeping in mind that if engine is not running on its normal working temperature.

(1) It will decrease the air/petrol mixing efficiency .
(2) It will effect the distribution of petrol/air mixture to each cylinder.
(3) This will decrease the volumetric efficiency of the engine resulting in increased fuel consumption .
(4) The engine oil will get fouled prematurely resulting in more oil changes .
(5) The fouled engine oil will result in the premature engine wear shortening the engine life.
(6) Vibrant and rough idle (low speed running).
(7) Engine will never give its full power and torque .
(8) It will increase the fuel consumption without increasing the output of the engine .

[ziddipathan]

I must say that the subject mentioned in the post is very elaborately explained but i must say that every car has a different scenario keeping in view its components. Although its very much right that standard SOP is exactly the same as explained in this thread but in my opinion it cant be applied to all cars which have different aged components totally dependent upon owners pocket.
Another important factor is we dont get good quality parts as compared to past times when auto parts were directly imported from japan, these days written "made in japan" is hardly japan originated as japan these days dont have manufacturing facilities for older models spare parts, the car is up for export to our third world countries just after use of 4-5 years which are only 50K driven maximum.
Mostly the parts which are called "made in japan" are made in china, made in taiwan, made in thailand, made in korea etc etc. One more interesting factor China has different quality parts like A, B, C, i suppose the A quality comes in a supreme packaging with the label "made in japan" the B quality comes in a different wrap under the label of "made in taiwan/korea/thailand) and the C quality is accordingly named finally "made in china".
i must also mention here that i belong to shipping industry here in pakistan working in the sector of imports from overseas. In the commodity of automotives, my major clients are:
Indus motor company
Gandhara Nissan
Atlas Honda
Pak Suzuki motor company
Hinopak
90% of there import sectors are:
China (Shanghai, Ningbo, Qingdao, Guangzhou, Dalian, Foshan, Shenzhen etc)
Thailand (Bangkok/Laem Chabang)
Taiwan (Kaoshioung, Keelung, Taichung)
Korea (Busan/Pusan)

Remaining 10% of there imports are manufacturing machinery from europe and usa.

Major commodities imported from Japan these days are mainly JDM vehicles or the scrap automotive parts from japan which we buy from our kabaddi bazar in Shershah Karachi.

Again i must say that the advice written is absolutely correct for engine temperature's importance but its also important to consider your cars components as well before putting your car on advised cooling system with auto fans and thermostat valve etc.

[Xulfiqar]

the problem is not of the chinese sourced parts, this problem has been in effect since the 70s as my elders I have told me. Its more about technique, e.g. its not a bad quality concern that nissan FWD and nearly all Honda FWD engines have a bleeder nipple to remove air pockets.

The biggest problem is short cutting everything, you can see it everywhere that an average person driving a car in Pakistan thinks that the temperature needle should always stay at C. The mechanics have a standard procedure passed down by their ustaads that remove the Tstat, dump the coolant, fill with plain water, lock the fan to run all the time and set the customer on his way. The mechanics are to blame - they have become lazy and refuse to be educated with new techniques, to top the cherry the average customers are too aloof to discuss common sense now.

speaking of chinese parts - I have had good experience with them, but not all, some of the cheap knock-offs are downright criminally bad - Its in the hand of the buyer though.

[imran2d]

I liked the above two posts written by Mr.Xulfiqar and Ziddipathan but again I agree with Mr.Xulfiqar that mechanics have changed the trend and second thing we say commonly that my car is very nice I just change oil filter and fill the fuel, no maintenance is required, but in actual we should think about car parts in relation to the mileage and the car age, for example if we have mileage above 60,000 we should inspect or change rubber hose pipes connected to radiator and we should observe if any abnormal sound comes from electric cooling fans and we should change the coolant atleast every two years, so with this we can have a guarantee that we will never stop on highway without help.

these Rubber hose and fan stuff will not be so expensive for poeple if they change these things after 5 years but poeple only change when they have breakdowns.

[faziljaved]

both running engine at high temperature and runing it at low temperature is equally harmfull.
running engine at higher than recommended temperature can cause the thinning of oil which can lead to seizure of engine as the thin oil looses its lubricity. it can also cause premature combustion which can damage the crank bearings and low efficiency. the engine can be damaged very badly
running engine at a lower than recommended temperature is also very bad. as the oil is thicker than it should be so there is more resistance between the moving parts of the engine therefor it runs under load. which causes bad feul efficiency. as you mentioned the pistons are also loose and not properly fed the feul contaminates the oil beneath the pistons and there is excessive blowby.
the feul burns properly when the engine reaches its optimum temperature. therefor when the engine is colder, the feul does not burn fully leaving you with low milleage.
these were a few points i just wanted to make. and yes never run your car with the fan directly connected and running all the time.

[MoizIrfan]

To be honest i am afraid of adding expensive coolant just because I can't detect why the radiator is reducing water even though my radiator and all hose pipes are new.

[afarooqi]

the picture shows the radiator fan thermoswitch in the red circle - but it seems like a single wire version.

Xulfiqar, that what I am saying that this single wire thing is the gauge that moves temp gauge and not fan. Fan switch is two wire in my wire whose female end is present but uplugged.

[afarooqi]

the problem is not of the chinese sourced parts, this problem has been in effect since the 70s as my elders I have told me. Its more about technique, e.g. its not a bad quality concern that nissan FWD and nearly all Honda FWD engines have a bleeder nipple to remove air pockets.

The biggest problem is short cutting everything, you can see it everywhere that an average person driving a car in Pakistan thinks that the temperature needle should always stay at C. The mechanics have a standard procedure passed down by their ustaads that remove the Tstat, dump the coolant, fill with plain water, lock the fan to run all the time and set the customer on his way. The mechanics are to blame - they have become lazy and refuse to be educated with new techniques, to top the cherry the average customers are too aloof to discuss common sense now.

speaking of chinese parts - I have had good experience with them, but not all, some of the cheap knock-offs are downright criminally bad - Its in the hand of the buyer though.

I 2nd to xulfiqar bhai, as hardly you are able to find any mechanic who is working upon standards. they are all just jugadoo's.

[Xulfiqar]

Xulfiqar, that what I am saying that this single wire thing is the gauge that moves temp gauge and not fan. Fan switch is two wire in my wire whose female end is present but uplugged.

then I have already posted the wiring scheme for you, trace the one wire that switches off the relay - it should be coming from the fuse/relay box and that wire should be connected to one pin of the coupler, the other wire should be ground.

[2468]

if direct fan has so many disadvantages then why so many mechanics suggest that and so many cars running with direct fan

[afarooqi]

then I have already posted the wiring scheme for you, trace the one wire that switches off the relay - it should be coming from the fuse/relay box and that wire should be connected to one pin of the coupler, the other wire should be ground.

Sir jee, wiring scheme to samj aa gayee, magar switch kahan lagay ga? jis ko ap fan switch keh rahay thay (diagram may wo to sensor hai). aik or hole hai wahan magr usko kisi nay block kya hoa hai. muje yeh confirm karna hai k fan switch wahan lagay ga ya nahi.

[afarooqi]

Xulfiqar bhai, thanks for ur replies and sorry for bothering you again and again with silly questions.

[dr3vil]

i got my previous car with a direct Fan and when i did it auto my self performance was good
it was a mehran and with direct fan it was always faulty with water body etc and it had T valve removed
our local mechnics are to blame