temp reading becomes higher after replacing temp sending unit

[mantoy]

my car's old temp sending unit was replaced because it's already worn out . what i noticed is the temp gauge reading becomes higher after replacing the sensing unit with a new one. almost 3/4 (a little above the halfway mark) ang normal reading.

before when i was using the old temp sending unit ang normal reading ng temp gauge is just 1/4 (a little below the halfway mark).

di naman masyadong mainit engine ko pag binuksan ko hood. di naman nababawasan coolant/tubig sa radiator. my water pump was just replaced 3 mos ago. wala ring leak sa mga hose.

temp gauge na ba problem ko? or the replacement part that i got sends inaccurate reading?

[Field Master]

How do you know that your temp gauge is worn-out? What was your indicator?
I encountered the same before (2nd hand pajero), dash is registering very low temp, about 1/4 just like yours. At first I was impressed kala ko ganoon ka efficient ang cooling system ng pajero. But I doubt if it is giving me an accurate read-outs kasi when i compared this to other pajero I could single out my ride as OUTLIER, namumukod tangi. What I did was to borrow my friend water coolant sensor at nilipat ko sa car ko only to find-out na tumaas nga ang reading. That's the time I decided to buy.
Kung halfway mark ok lang yun and this time less yun risk mo of running with overheat engine without you knowing it. Subikan mo maghanap nung katulad mo ng ride then isolate mo yun sensor.

[mantoy]

i had to replace the old temp sending unit kasi grounded na and erratic na ang reading. nasa redline sya pag tumatakbo ka pero pag naka-idle ka a little above C lang ang mark which is so weird. its normal reading used to be 1/4 (a little below halfway mark)

the problem with my new temp sending unit eh sobrang taas naman ang normal reading nya. lagpas na sa halfway mark (3/4) which i think is also not correct kasi di naman ganun kainit engine ko.

my ride nga pala is '89 corolla.

[Ungas]

When was the last time you changed water and coolant mixture? What ratio is your mix? Or you may need annual radiator cleaning/flushing?

[Field Master]

The temp sensor is a variable-resistance sensor. To check the coolant-temperature sensor yourself, use a VOM -- or digital volt/ohm meter. I used this to check the resistance of the meter to verify that it is working. With the ohm scale on the meter set to 20k, the black lead is connected to ground and the red is brought into contact with the terminal on the sensor. It should indicate some reaking above .10K (depending on sensor spec). Generally, any resistance is an indication that the sensor is working, if the reading is zero or infinity then busted na yan.
Check mo rin yun recommendation ni sir ungas.

[yebo]

how do you know na hindi nga talaga dapat 3/4 ang reading? used a thermometer? are you sure yung assumptions mo ang correct, or yung temp reading ang correct?

[mantoy]

so if the temp reading is correct (3/4) , is there anything wrong with my cooling system? stable sya sa ganun reading whether the aircon is on or off.

[mantoy]

Originally posted by Field Master
The temp sensor is a variable-resistance sensor. To check the coolant-temperature sensor yourself, use a VOM -- or digital volt/ohm meter. I used this to check the resistance of the meter to verify that it is working. With the ohm scale on the meter set to 20k, the black lead is connected to ground and the red is brought into contact with the terminal on the sensor. It should indicate some reaking above .10K (depending on sensor spec). Generally, any resistance is an indication that the sensor is working, if the reading is zero or infinity then busted na yan.
Check mo rin yun recommendation ni sir ungas.

magkano naman yang VOM na yan? at san makakabili?

[Field Master]

VOM - Wag ka ng bumili, marami kang mahihiram nyan sa kapitbahay, yun mga friend mo na electronic enthusiasts meron nyan. Multitester kung tawagin yan ng iba. Yun sa akin nabili ko analog type 10 yrs ago 500 pesos yun.

[niky]

Sounds like an old problem of mine. It doesn't mean that if the sensor is by the same manufacturer that it will give the same voltage to the instrument cluster.

[doc eric]

[ram]

Field master's recommendation is sensible. Interchange your sensor with someone else's and verify if you still have the same reading. That's one of the common methods of troubleshooting.

[tarugs24]

Mas ok cguro kung thermometer ang gamitin mo since temperature ang problem mo provided alam mo ang working engine temperature ng kotse mo, VOM can only detect if your sensor is open or shorted....

By the way check mo rin yung thermostat valve baka restricted yung flow ng tubig.

[blackbox710]

[SIZE=3]
I used to have almost the same prob with my 93 Sentra. A lot of engineers and mechanics advice not to trust the stock engine temp sensor + gage. I used an infrared digital thermometer and measured various points in the engine. For Nissan Sentras 1990 - 2004, the needle should be between 1/3 to a little bit below 1/2. If it goes over the 1/2 mark often, specially if your engine has just been running for less than 15 minutes, then it needs to be checked asap.

Normally, operating temp ng gasoline cars is 85 deg C up to 98 deg C (measured at the radiator coolant), according to Toyota and Nissan engineers. Some Diesel engines operate about 10% hotter.

Water and coolant will normally boil but the design of radiators and cooling systems make sure that the water doesnt:

- the system is pressurized up 9 - 15 psi and the radiator cap makes sure that it stays that way. The higher the pressure, the higher the boiling point of the water, i.e. the pressure keeps it from boiling.

- ethelyn glycol in the coolant gives it a higher boiling point and a lower freezing point.

-various causes of overheating may range from system leaks, low coolant level, not changing your oil when needed (bad oil = more friction = more heat), latak and rust in the cooling system. I had the water jacket cleaned up when I had my engine overhauled. I flush the cooling system ( radiator and engine block water jacket) with running tap water for 7 minutes using the garden hose once a month.

- I recently discovered that using purified drinking water (P30 = 5 gallons) is more effective than using 30-70 tap coolant-tap water. It lessens the chance of rust and latak in your cooling system somehow. <DO NOT USE MINERAL WATER>

Next project - in dash digital themometer using the LM35 Thermistor as a sensor. So I can monitor the engine temp more accurately, I plan to mount the sensor around the upper rad hose area.

Daming circuit diagrams available sa web, pwedeng DIY, parts are available sa Alexan Megamall! [/SIZE][SIZE=3] target completion August 20 pa, daming work sa school eh...[/SIZE][SIZE=3][/SIZE]

[userfriendly]

Don't use mineral or purified drinking water.
Use DISTILLED water aka wilkins etc... with correct coolant mix. Distilled water has no impurities and will not cause rust build up.
Flushing your radiator once a month is overkill. But if you have the time and money it will really keep your rad clean.

[4JGtootsie]

Distilled is the best. Hindi basta nag evaporate, malinis at hindi basta nagiiwan ng dumi sa system.

I know luma na ito but bigay ako opinion. Be sure tama ang part number ng temp sending unit specific to the engine, year and model.

[joey]

my car's old temp sending unit was replaced because it's already worn out . what i noticed is the temp gauge reading becomes higher after replacing the sensing unit with a new one. almost 3/4 (a little above the halfway mark) ang normal reading.

before when i was using the old temp sending unit ang normal reading ng temp gauge is just 1/4 (a little below the halfway mark).

di naman masyadong mainit engine ko pag binuksan ko hood. di naman nababawasan coolant/tubig sa radiator. my water pump was just replaced 3 mos ago. wala ring leak sa mga hose.

temp gauge na ba problem ko? or the replacement part that i got sends inaccurate reading?

baka maling temperature sending unit ang nabigay sayo bka for lancer,etc.
or ilinaw mo kung for xl or gl ung nakuha mo (bka lang magkaiba cla)

[Asus700]

this thread is so old na pala (nov 2004) and narevive pa.

hope mantoy solve his problem

[joey]

this thread is so old na pala (nov 2004) and narevive pa.

hope mantoy solve his problem

aasssus maryosep! hahaha binuhay pa ah