Cultus Carby Temperature drops

[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

[xzap042]

Correct

[dani_kk]

Very well said... Whether it is 4row or 5row, we will rule it out... If that was the case people should have started downgrading to single row for winters... As many cars have tstat value of 82degrees & few Nissan system also have 76 degrees with 2 row radiator in it. But the heater works like a charm...

So first of all, let the car idle & see when the fan operates, by holding the two pipes of radiator see if both pipes are hot. If one pipe is cold then we've a coolant leak somewhere or we have a bad tstat.. But if both pipes are hot then it shows cooling system is working properly & it could be either cheap Chinese gauge installed which has a problem of rising up just before the fans are about to. Operate & then it goes down giving a impression of system cooling down. You can confirm after the fan turns off both pipes would be hot just like they were before fan operation... So now this is an explanation to temperature reading flactuation...

Now moving to the heater system, well a blocked, rusty heater core doesn't heats the air inside the car properly & once the car is at fan turning on temperature it gives slightly better heat & when temperature drops to 80 degree range it starts throwing a slightly less heated air from your vents... You need to replace the heater core in this situation.

So your problem is of a inaccurate temperature switch & a clogged choked heater core... We recieve a high Number of cars with such issues in winters in our workshop..

[ahsan.pmd]

The heat needle is at dead cold when car is started.

[ahsan.pmd]

well explained

[ahsan.pmd]

I did both things first before making post here. I changed the thermostat housing and replaced the valve with a brand new Japanese one. Still the issue persists

[ahsan.pmd]

Daniyal brother Thanks alot for your detailed answer. I'll check this pipes things when the fan starts and after it stops and let you know here

[ahsan.pmd]

@dani_kk I did the test. At cold start both pipes are cold and then the top one starts to become warm as the temperature rises, then I can feel the bottom one also getting warm as the temperature is rising. When the fan operates both pipes are very hot and remained hot even after the fan turned off. Do you reckon now that thermostat is fine? The temperature gauge being used in the one which is mounted near the thermostat. The other one which is attached to the carburetor housing is broken and not coming out. Is it ok to use this temperature gauge? The rubber pipes of heater core are also hot when fan operates

[xzap042]

I still recommend to take out the thermostat, put it in a pot of water and measure the exact temperature at which it begins to open. I believe yours is opening too early.

You cannot tell the difference between 60 degrees or 90 degrees just by touching the rubber pipes. Both will feel really hot.

[Xulfiqar]

Please make sure you use a pot that you wont use for food cooking purpose later on.

[sayedgulhassan]

The same issue I'm facing after coming back from karachi to isb on motorway and isb highways temperature stays here and also i feel difference in heater at high speed and traffic/idling.

T valve was checked a year ago and it was properly opening and closing in boiling water.

[xzap042]

T valve was checked a year ago and it was properly opening and closing in boiling water

You cannot say it's good just by checking opening/closing in hot water. It needs to open at a specific temperature (82/88) and close at a specific temperature.
With time the spring in T valve loses tension and it starts opening too early hence the issue you are noticing. I've seen perfectly good looking T valves opening as low as 55-60 degrees. I have gone through same issues.