Vehicle engines are meant to run well at a certain temperature. It could be 80, 90 or 95 degree centigrate, depending on the engine. only when it warms at the operating temperature that longevity of the engine is ensured.

your engine is emiting black smoke from the exhaust now, I believe, because its running rich (excessive fueling). its running rich because its no longer warming to the operating temperature which is the work of thermostat. as long as your engine keeps running cold, the ecu will signal the injectors to spray excess fuel, believing that the engine is still cold.

Your raditor electric cooling fan is no longer coming on frequently as it used to because the fluid/coolant in your radiotor are always cold & the sensor on raditor that is suppose to on the fan when coolant temperture starts exceeding the normal operating temperature its always sensing the engine temp very cold.

If i were you, I would replace the thermo like you said you would do & have a piece of mind.

Ikenna.

ikeyman00:

ikenna

then if thats the case going by what u have written fuel consumption comes down to the climate the car is driven ( hot or cold weather)

wonder the reason it never shows up on the car manual.

since the sensors triggers off the ECU to pump more fuel when it reaches cut off temperature abi

as for good mechanics for injector in naija, well im aware of thats, like they say once its gone replace it? once open thats it for them

Ikenna351:

It depends on your car, Honda, wiring system. On Peugeot cars, like 2 of my cars, they have sensor on all their radiators, known as radiator sensors. The electric radiator fans & A/C fans are connected to the radiator sensor. The sensor serves as a trigger or switch to the fans. When you start the engine. The temp will still be cold or warm. The fans will be off. When the temp rises to beyond the normal engine operating temp (when you are in traffic jam or the car stationary & engine idling), the thermostat will open, & the hot coolant in the engine walls & cylinder heads, with the help of water pump, will flow into the radiator, while the cold or warm coolant in the radiator will flow into the engine walls. As soon as the thermostat senses or feels the coolant with lower temp, it will close & the coolant will remain in the engine walls. When the hot coolant flows into the radiator, the radiator sensor will sense the hot or high temp coolant. The radiator sensor will then switch on the radiator fans & sometimes the A/C condenser fans, to cool the hot coolant in the radiator. After some seconds or a minute, the coolant temp in the radiator will come low & the sensor will switch off the fans, since the radiator temp has come down to low temp. The fans will remain off for a long time until the thermostat opens again, if the car remains stationary/not moving while engine is on. Breeze that comes in through car front grille while car is moving, especially while on speed, is enough to cool both coolant in the radiator & coolant in the engine walls . So if the car is moving, the thermostat will not open & the fans wont spin. It ensure the lifespan of the fan motor.

But am not sure Hondas have radiator sensor. I think they use CTS (coolant Temperature Sensor) or temperature sensor on thermostat housing to trigger on/switch on the radiator electric cooling fans. If your fans runs constantly, it could be that it has been bypassed & connected to ignition switch to run whenever the ignition is switched on.

Also remember that if the tthermostat is removed, the engine will always run cold & the cts will always send signal to ecu that the engine is always cold. Cts determines the amount of fuel that goes into the combustion chambers via injectors, when engine cold & hot. Engine needs excess fuel to start a cold engine. Cts that senses temperature of coolant, will signal to ecu when starting a cold engine that the engine is cold. The ecu will command injectors to spray in excess fuel for the engine to be able to start, when clanking a cold engine. But when the coolant temp risese, with the help of thermostat, the cts will sense the high coolant temp & will signal to ecu the hot temp of the engine & the ecu will lean or reduce the amount of fuel that injectors spray into the cylinders. That is why thermostat are put in the cooling systems to warm the coolant for cts to lean fuel into the engine. So if thermostat is removed, the cts will always signal to ecu that engine is cold (even if the car has run for two hrs) & the ecu will always command the injectors to spray in excess fuel, believing that the engine is cold all the time. So, thats why removal of thermostat makes engine to consume excess fuel via cts.

Hope that helps?

Ikenna.

kc007: Can a thermostat work normally, that is opening @ required temperature if coolant temperature sensor is malfuntioning?

Ikenna351:
@ Poster,

Did you at any time flushed & refilled the car cooling system/radiator without bleeding the cooling system? To be honest, your thermostat might not actually be faulty. if you change your car coolant without bleeding the system, the system will have what we call airlock. The airlock will make the engine to suffer what we call airpocket(overheating of cooling system). what & how do I mean? When you flush your radiator or cooling system, air will fill the vacuum, formely filled with fluid. Then, while pouring in fresh coolant, the air in the engine walls will be trapped, since the thermostat is shut/close. The air trapped is called "airlock". If one run the engine with the airlock, the air trapped around the engine walls will be boiling the coolant beyond the operating temperature & the boiled air ( in fumes) wont be able to pass the hole on the thermo when it opens. Thus, the engine will be overheating, few minutes after the engine starts. The engine will be regarded as suffering from "airpocket", which can easily blow up the Cylinder head gasket, if care is not taken.

Whenever you decide to replace/fix back the thermo, make sure you bleed the cooling system from the bleed screw. You should be able to locate the bleed screw when you refer to your car owner's manual. If you dont have the manual, Trace the screw on all the hoses linked to the radiator, you will see it. Your manual should be able to guide you on how to bleed the cooling system. If you dont know how to bleed, ask & I will explain.

There is a way you can find out if a thermostat works or is ok. Pour some water in a kitchen pot, put the thermo in the pot filled with water & boil. As the temperature rises to the temperature the thermostat is supposed to open to pass fluid, it will open right there inside the pot, even before the water start boiling. But like I noted in the earlier post, you need to check your car owner's manual to know the operting temperture of your car cooling system, which will tell you the temperture when your thermo should open.

Like I would always tell people, stop listening to clowns/destroyers that call themselves auto mechanics/rewires here in Nigeria. Bunch of Clowns! Arm yourself with the your car owners manual, workshop manual & wiring diagram. Start to learn how to fix your car, at least, the basics by yourself (DIY). We cant be too busy or too big than the western world that diagnose & fix their vehicles by themselves. It can be scarely in the begining, but with time, you will know more than those clowns. You have access to internet which is a big impotant tool those clowns dont have to update themselves with the modern way of diagnosing a car. I dont remember the last time a mechanic or rewire touched my car. It feels very good/satisfactory when one diagnosed & fixed his/her car by him/herself. Its is the best way of ensuring PREVENTATIVE MAINTENANCE.

I would also advice that you search for an online community or forum of your car .e.g. Honda Accord, Honda Civic, Toyota Camry,etc. No matter the make or model of your car, you will find a forum online where you will see your fellow owners of the car discussing & suggesting to a fellow member what to do & how to go about fixing his car problem, with a similar experience. you will learn a lot from others experience. There you can also get & download free owners & workshop manual from fellow members. Its so unfortunate that we are not getting such good things here in Nairaland autos. Instead, cars for sale. Unlike other forums that have sections for cars for sale & sections for discussions.

Ikenna.

Oyewolee:
@ikenna351, I use a 1999 Toyota Camry model, I bought from a friend who used it for a year before I got it from him. The car has used 2years with me but for some time now, the car gulp fuel excessively and it is getting alarming. Coming across this discussion on the thermostat got my attention cause my friend told me he removed the thermostat about 3years ago due to the car cooling system error. My question is if I can still place back the thermostat. Thank you.

Oyewolee:
@ikenna351, I use a 1999 Toyota Camry model, I bought from a friend who used it for a year before I got it from him. The car has used 2years with me but for some time now, the car gulp fuel excessively and it is getting alarming. Coming across this discussion on the thermostat got my attention cause my friend told me he removed the thermostat about 3years ago due to the car cooling system error. My question is if I can still place back the thermostat. Thank you.

honmusa:

Is good you restore your thermostat back and connect your fan to default but before you that you need to check your cooling system integrity for any leaks so as not to cause the hidden overheating that has been suppressed to come back .
For the previous owner to remove the thermostat before ,there has been a pending overheating issue that was suppressed but not solved .So ensure that the root issue of overheating is resolved by taking your car to a competent mechanic that has the equipment to resolve it for you before connecting your thermostat back .
If you are in need of a professional to resolve this for you with the right equipment and fix the thermostat and fan default connection .call autologic @08061166316