Cultus Carby Temperature drops

[ahsan.pmd]

Dear experts. I am facing a a problem in the car that the operating temperature is not maintained properly. Thermostat is there and although the temperature needle starts moving up but when driving continuously the needle doesn't reach the middle (at optimum operating temperature). Needle even drops near to Cold mark when driving at high speeds on highways. The only problem which comes to mind is that thermostat is not closing properly but I removed the thermostat and installed a new Japanese one and still the issue is same. Also I checked both thermostats but placing them in hot water and saw both are working fine (opening and closing). Why the car is not able to maintain the optimum temperature? Due to this heater is also not working good.
There is no overheating or coolant reduction issue otherwise.

[Xulfiqar]

How bad is the system rusted!

[ahsan.pmd]

I would say that system is not rusted. I used coolant in the last few years and cleaned the cooling system as well. Recently engine was rebuilt.

[SER_GTR]

auto fans? thermostat?? all ok.

do you feel car getting hotter and fans kicking inn and going off while the needle is dropping and cold???

check physically too whats actually happening

it could be bad sensor or loose. Faulty wiring also

[ahsan.pmd]

fans auto, thermostat new installed (checked its working oustide)
In stop and go situation or standing car the needle reaches the middle and then fan kicks in and needle comes down a little but the issue is that while driving it comes below middle very near to the bottom end. One thing that wire is attached to the sensor near the thermostat housing pipe (there are two sensors in the cultus carby don't know why though) the other one is broken. I am ruling out sensor malfunction since the heater temperature also drops when needle is down it means engine is getting cooler than the operating temperature

[SER_GTR]

is there a bigger radiator installed in car? or dual barrel??? (double nali)

for 2 sensors....one is for temp gauge while the other is for auto fan.....

share pictures of sensors intact and broken one

[ahsan.pmd]

Radiator is dual channel. Yes the wire is attached to the fan switch one. The broken one is under the air filter. I'll share picture soon. Just to mention that the thermostat installed is on 82C rating. I was just reading cultus manual and found out that two different thermostats either 82C or 88C is mentioned while manual doesn't say which one is for carby cultus G10 engine. Is it also possible that lower temperature rating thermostat is the issue?

[SER_GTR]

yes it could be the reason as its opening early and causing more temp drop as radiator is dual barrel also

search check on forums and you may get information. there are plenty of cultus restoration post which can help

[ahsan.pmd]

Thanks brother

[Moderator]

[suzukialtomehran]

People change thermostat to lesser degree like 82, your case is same i think. Curby cultus is prone to overheat so i think you should stick to this situation and do not fiddle with the cooling system

[Hassan1991]

Efi also got 88C i think.

[xzap042]

Your thermostat is bad and opening very early. I would suggest to change it. You can test again in water and measure the temperature at which it starts to open. It should match with is rated temp.

[ahsan.pmd]

First time when engine is warming up the temperature rise seems fine. I am thinking about one possible reason which is the use of dual channel radiator. Originally this cultus comes with a single channel radiator, may be use of dual channel radiator is the reason for this improper temperature regulation

[xzap042]

No. Even 4 channel radiator cannot cause over cooling. Thermostat is solely responsible for it. It should close below 82/88 degrees whichever is installed. Your thermostat is opening too early

[capsat]

you may need a different thermostat valve as in Suzuki Bolan - There is a likely chance that cluster gauge has developed some corrosion. 1988-1993 Swift was notorious for such error.

2 / 3 / 4/ 6 channel radiator will not make any difference. The coolant capacity of the engine channels remain unchanged. Thermostat will open / close only at the specific temperature.

@Xulfiqar @VCheng
@rajaatta @dani_kk
@SER_GTR @nomi01
@hassan1991 @babarhyd

please correct me if am wrong

[VCheng]

The radiator design determines its maximum heat dissipation capacity. The thermostat determines how much of that capacity to use at any given time. The sensor and its wiring determine what is displayed on the instrument cluster.

[Xulfiqar]

Is the thermostat actuallly fully closed when cold?

[rajaatta]

Seems like faty thermostat or the housing of the thermostat is corodded. I have seen some cultus Carby with corodded water jackets resulting in cold temp at higher speeds in winters.

Check the thermostat jacket and try to get a brand new thermostat jacket along with thermostat your problem would be solved

[capsat]

gents do i understand correct that even if 2/4/6/8 channel radiator is installed with high coolant capacity, the engine with thermostat will operate at the very same say: valve opening 88 / 92 C switching automatic fan on/off at 98 /93 C ??

i tried to explain it with example of domestic geyser in desi language to few but i failed. Geyser kinna vee wada hoi gas burner thermostat setting sai he haan haaf hoaay ga, burner di gas supply kaam karan tou koi farq nai painda.. jaasti dayr burner bharkay ga gass unni kharch hoi gi