2001 suzuki swift - thermostat replace?

Reasons the Temperature Gauge Reads High

If the temperature gauge reads high, it could mean your engine is overheating. Another reason your reading might be high is you could be losing coolant. A small leak or evaporation may cause your radiator to slowly lose coolant. A third reason your temperature gauge reads high could be because the thermostat is broken. If this is the case, you may need a coolant temperature switch replacement. The last reason the temperature gauge could read high is because of a water pump, or water pump gasket failure. If the water pump is malfunctioning, it may need to be replaced by a professional.

What to Do If Your Temperature Gauge is High

If your temperature gauge is reading high, it means your car is overheating. This is a very serious matter and you should never drive an overheating car. If your car starts to overheat, shut off the air conditioner and open the windows immediately. If this does not reduce the overheating, turn on the heater as high as it can go. If this still doesn't work, pull over on the side of the road, turn off the engine, open the hood carefully, and wait until the vehicle cools down. Never open the radiator cap while the engine is hot - coolant can spray and burn you. Once the vehicle has cooled, take the car to a mechanic right away so they can diagnose the problem. Cars are especially susceptible to overheating in hot climates, like what's common in cities like Los Angeles, Phoenix, Las Vegas, or Atlanta.
The temperature gauge is an important tool in your vehicle that shows the temperature of your engine's coolant. Contact YourMechanic and have your car inspected for overheating if it reads too high, as this can cause serious problems...

Reasons the Temperature Gauge Reads Cold

On most vehicles, the temperature gauge reads cold until the engine has run for a few minutes. If the temperature gauge still reads cold after the engine has warmed up, the gauge may simply be broken. Another reason the temperature gauge could read cold is if the thermostat in the vehicle stays open. With the thermostat stuck open, the engine can be overcooled, causing a low temperature reading. If this is the case, the thermostat may need to be replaced.

check coolant level, if low fill radiator and check for leak. if full the temperature sending unit probably needs replacing

Did u "burp" system...leave cap off and let run f
Until thermostat opens and cycles..

The thermostat "seals" the cool coolant giving up (rejecting) heat in the radiator & heater core from the hot coolant absorbing heat in the running engine "block".

When the coolant in the engine reaches a specific temperature (180 ~ 195 degrees) as determined by the value selected by manufacturer or when replaced, it opens and allows the hot coolant in the engine block to be pumped out to the radiatot & heater core for cooling and the cool coolant in the radiator / heater core is pumped into the engine block - replacing the hot coolant. The thermostat senses cool coolant in the engine block and seals shut until the temperature of the coolant in the engine block rises to 180 ~ 195 degrees again. This process continues over and over for as long as needed.

You should check to make sure that the coolant level in the reservoir / radiator is sufficient by checking when cold. Do NOT remove a radiator cap when it is hot! With the cap off, start the engine and add additional coolant as the engine warms up to normal operating temperature. If coolant levels are ok, the trouble could be related to the thermostat or possibly a faulty temperature sending switch. This means that the temperature of the coolant is fine - but the switch or sensor that converts the temperature to a voltage for the gauge on yur dashboard is the problem.

If the temperature is fluctuating up and down, you should have it fixed. Good luck!

The two most common reasons are low coolant or a sticky thermostat.
Low coolant can cause air pockets in the cooling system, and a sticky thermostat could be slow to open and close.

Watch the temp gauge when the electric radiator fans come on. The temp sensor that controls when the fan comes on may be faulty.

Check your coolant level visually by removing the radiator cap (only when it is cold). Also make sure the coolant temperature sensor for the cooling fan is functioning properly. These are set to operate the fan when the engine coolant reaches a predetermined temperature. These go bad in time and need replacing. Sounds as though yours may be working intermittently.

The most likely cause is the thermostat stuck in the fully open position which allows maximum coolant flow between the engine and radiator in very cold conditions. In such such conditions the coolant temperature will not increase to optimum and will run cold constantly.

You will need to have the thermostat removed and inspected. It is an inexpensive item and I would replace it with a new one.

Have you check rad fan operation?

Is yours a SOHC or DOHC?

G13B 1-CAM 16valve (SOHC)
When cold (Coolant temperature is 15 – 25C or 59 – 77F)
Intake 0.13 – 0.17 mm (0.005 – 0.007 in.)
Exhaust 0.23 – 0.27 mm (0.009 – 0.011 in.)

When hot (Coolant temperature is 60 – 68C or 140 – 154F)
Intake 0.18 – 0.22 mm (0.007 – 0.009 in.)
Exhaust 0.28 – 0.32 mm (0.011 – 0.013 in.)