Does anyone know what sort of readings ones should be getting from the coolant temperature sensor while at idle for a 2004 Discovery?

I had a scanner going to monitor the actual idle readings and am wondering what sort of numbers I should be looking for, what is considered normal?

 

I sit at 194 197 idle

 

You should try search. With the stock 190 degree t-stat, you should get around 200 to 210. With a 180 degree t-stat you should see 187 to 198.

 

Sorry, I should have been more clear. When the scanner was hooked up and reading the actual activity of the coolant temp. sensor it was at a flat line of 0.8 at idle and also when increasing the throttle it stayed the same.

My engine temperature was too high at 214 at idle with a 190 t-stat.

I have another thread here about my cooling fan running in cold weather and I am still trying to track this all down. The fan clutch is brand new, the t-stat was replaced this last summer but I am replacing it with another new one tomorrow and also putting in a new temp sensor on the radiator.

 

I'm also running in the 214 at idle range with it peaking at 221 at times.

 

If reading the volts for the coolant sensor, .8 is over 100C. My scanner reads out in degrees, so the OBDII data sent to it is in degrees.

Also, the temp sensor that drives the scanner (OBDII port) is not mounted in the radiator, it is in the top of the intake between the alternator and AC compressor. Which sensor on the radiator were you planning on changing?

Your electric fan would be running if you get over 212F, does not matter how cold it is outside.

I would agree that idle in cold weather at 214 is high. What does it go to when you are at say 50 mph on the road? You may want to carefully check all the radiators (AC condenser, oil cooler(s), and main radiator) for obstructed fins (mud and trash); and if you have an infrared thermometer available you can meter the fins of the main radiator, top vs bottom rows. A good radiator will be maybe 10F difference top to bottom. A radiator that is partially full of sludge will be cooler on the bottom. Such a radiator won't be able to keep up with heat at idle, but may cool of at highway speeds.

It is true that a coolant temp sesnor could be "bad". I know when mine is unplugged, the open circuit makes the ECU think it is -40F.

As you have already "discovered" the factory temp gauge is pretty vauge, stays at 50% without much movement. I have attached a pix of the coolant temp sensor. There are other sensors on and around the radiator, but they are not the engine coolant you need to be watching.

 

Savanah,

Thanks, as always, for your advice and opinions.

I do not have the sensor between the alternator and AC as you have shown in your picture.

**Correction** I do have that sensor, I just looked! It's just doesn't sit as high as yours and is partially tucked under the plenum. Also, the small diameter coolant hose next to it appears to be leaking.

There is also another temperature sensor in the radiaor and the wires from that run up the passenger side of the engine, up behind the alternator and then run under the plenum. I just checked it also and the plastic harness that clips onto the sensor is broken and it may not been making the right connection as I also just discovered!

Any idea which sensor this is in the radiator? The other sensor is mounted under the bottom radiator hose. Is it another coolant temp. seeing as I have secondary air? I guess it would be this one and if so are you familiar with it? http://www.roverparts.com/Parts/ERR2081.cfm


I do have a infrared thermometer so I will check the differences as your mentioned.

Thanks, as always, for your advice and opinions.

 

KindaGuitarded -

You too are idling at too high of a temperature. Does your cooling fan on the front side of the radiator come on when your temps are that high at idle?

As per other threads here, including one of my own, there are many suggestions as to what you should start checking / trouble shooting to find out what's causing your higher temps.

 

That one on the bottom of the radiator is used to monitor the thermostat. The ECU compares the one in the engine with the one at output of radiator, if the spread is too great a code is set that indicates the thermostat is stuck open. It is on page 320 of 1529 in the RAVE workshop manual.

Small diameter hose most likely runs to throttle body heater. That heater kit is like $25, hot coolant is used to warm the throttle body to prevent ice from forming and sticking the throttle open.

 

Savanah -

Ahh right on the hose to the throttle body heater. I replaced that throttle body heater about a month ago.

So I have no codes in regards to the t-stat being stuck open. Do I need to replace either one of the two sensors - the one in the engine or the one in the bottom of the radiator? When I replaced the throttle body heater I had some calcification buildup in it and I am wondering if the engine coolant temp. sender in the radiator might also be of the same.

If either one of these was not reading properly would I get a code or could it cause my temps to be higher at idle without any codes?