I have question about behavior of engine temperature indicator on my Logan. As weather start to be cold these days, I noticed that after driving some time on open road (i.e. 80 km/h in 5th speed), engine temperature indicator drops from 4 bars (which should be normal), to 2 bars. When I increase rpm, or lower speed for couple of minutes it turns back to the normal 4 bars. I've talk to Dacia service personel and they said that this is normal behavior and that it happens becuase of cold air (in association with relaxed engine).

So, my question is if it's really normal behavior?

It's somewhat normal, as you drive and accelerate the air current it's stronger. If you stop, the engine relies only on the fan to cool the water.

No, it is not normal!! As long as the engine reaches its normal working temperature then, as long as it is started it should maintain this temperature!! I believe that they should check the thermostatic valve which closes the circuit.

There is someone in the Romanian "technical issues" section of the forum whose Logan had the same behavior. The problem turned out to be the faulty thermostatic valve which was replaced and the temperature readings got back to normal.

So it's not normal for engine to cool better when you drive with 130 km/h than when you are parked?? That's news for me .

The thermostatic valve and the radiator fan will work so that the temperature should remain within operating margins.
I don't know about your car but in mine, when running the engine at idle for long time intervals, the fan will kick in and lower the coolant's temperature. And so I guess that at 130kph the fan is not needed (that often) because the thermostatic valve alone manages to control the temperature.

LE: a drop in temperature level under nominal value when not idling could mean that the thermostatic valve remains open.

I call another service and they told me the same - i.e that I shoud not worry, and that malfunctioning of thermostatic valve (abnormal temperature reading) will be present in all driving conditions (not only in "high speed/low rpm/cold weather" scenario).

Now I'm not sure what to think...

Did someone know where is thermostatic valve placed in motor compartment?

I think I found similar topic on Romanian part of forum "Nivel temperatura motor, trece foarte greu de 2 linii". Unfortunatelly, I do not speak Romanian
Could someone please summarize what people said in this topic?

There is a simple test for your thermostatic valve:

- simple theory: the valve opens @ 89C, allowing coolant to pass through to the radiator. The valve is located in a black junction box, bolted onto the engine head. There is one thick hose that connects to the radiator (the top one).

Now for the test - my assumption is that your valve, just like mine and many other's is stuck open. To test this condition, start the engine - the engine must be cold, ideally in the morning. Keep the car stationary and wait untill the engine warms a bit (1 minute should suffice). Then touch the thick hose (top one, goining to the radiator) and see if warm. If it is, then you nailed the cause - the water is warm - no chance it reached 89C, and yet the valve is open.

Cheers

Yes, it was already explained here, în post #3 & #4.

You must convince the authorized service that there is a problem with the thermostat and that they must replace that.

It is not normal to temperature to drop from 4 to 2 lines.

Like Stefan Says
Your car's thermostat allows coolant to circulate when the engine is warmed up and should be closed when the engine is cold so that the car can warm up faster. It's a fairly inexpensive part that's replaced easily, but when it fails, your car can overheat, causing costly engine damage.

Instructions
STEP 1: Warm up the car but don't let it overheat - don't let the temperature gauge go into the red. STEP 2: Turn off the engine. STEP 3: Open the hood. STEP 4: Find the upper radiator hose. It's black, is made of rubber and is about 2 inches in diameter, with metal clamps on either end. The upper hose goes into the top of the radiator. STEP 5: Locate the lower radiator hose. It looks similar to the upper hose except that it attaches to the bottom part of the radiator. STEP 6: Touch each hose very carefully (they can be extremely hot). If the temperature gauge is indicating that the engine is warmed up but one hose is hot and the other is cold, the thermostat is probably stuck closed, and the coolant is not circulating through the radiator. STEP 7: Have the thermostat replaced if this is the case.

STU

The thing I don't understand is why are the mechanics defending the manufacturers at all cost.

Once there was a guy who was pesuading me that it is normal for my car to accelerate withoout me touching the gas pedal.

... and which is on Logan very difficult to judge since it only has: 0, 2 or 4 "lines".
I never saw 1 or 3 lines fo the temperature on the display. Anyone?

So, it doesn't look like some precise measurement. So, Boris, take the hot/cold rubber hose test as suggested here - and if everything is OK - don't be bothered with that anymore. It is pretty normal for a any car that, when driving on a cold weather, with "relaxed" highway drive temperature drops a bit down... which can be seen if you have on old-fashioned analogue instrument in the dashboard. With Logans 0,2,4 - with reading 2 you only know that temperature is _somewhat_ lower than it should be - but, don't have any clue about actual temperature. It is about treshhold set to electronic when to switch from 2 to 4 lines.

Because they get paid a basic rate .Go to work fix it fuck it and forget the customer! the next one will be there in the morning ready for the three Fs
Stu

Ok, this morning I did test as Stefan_b sugested, and it seems that thermostatic valve is working as it should be. I turned the engine on, waited for about 2 min, and then checked the upper radiator hose - it was cold. In the same time, other hose which is going to the cabin (as a part of cabin heating system) was wormed a bit (which means thet coolant is circulating). If thermostatic valve is malfunctioning (stucked open in this case) the radiator hose should be warmed as well.

Then, I hit the road and drive until 4 lines has been reached. I stoped the car and checked the radiator hose again. This time it was hot.

So, it seams that thermostatic valve is workin quite good. Now, I can only conclude that my car has normal behavior, and that "0-2-4 lines" inidicator is not acurate enough (I also never saw 1 or 3 lines, and, of course, never above 4).

Thanks to all...

Could your electric fan be cutting in too soon??

Nope... The fan is working just fine...

Check the temperature sensor contacts (connector)... (!) When you will unplug the connector (3 contacts on the connector) the fan will turn on automatically... the contacts are marked "A", "B1" and "B2"... the A contact is designated for the temperature indicator... B1 and B2 are for the engine computer... In some cases the measured values could be distorted due to electrical contact problems...

Normal values for the temperature sensor:
*between A and ground:
- 50-80 °C = 927-825 ohm
- 80-105 °Cdeg. = 300-273 ohm
- 105 -115 °Cdeg. = 136-124 ohm
- over 115 °Cdeg. = 103 ohm

*between B1 and B2:
- minus 40 °C = 76.000 ohm +/-9%
- 25 °C = 2.000 ohm +/-5%
- 50 °C = 811 ohm +/-5%
- 80 °C = 282 ohm +/-3%
- 110 °C = 115 ohm +/-2%

I solved the "problem". First, little explanation... After more testing I noticed that temperature drops only when cabin heating is turned on (all other prerequisistes explained above should be met as well - cold weather, relaxed engine, relatively high speed...).

Now, the level of coolant liquid was between "min" and "max", BUT closer to "min". I did not add coolant since I bought the car, just checked the level periodically. As we know, smaller amount of liquid will be wormed faster then larger amount, but it will be cooled faster as well. Engine cooling system is designed to avoid engine overheating, and min/max levels for coolant liquid are set in accordance with that goal...

The "problem" occured because smaller amount of collant liquid circulating through the cabin heating system was cooled faster than relaxed engine could warm it up. The balance was set somewhere below 89 degrees which was enough for inacurate indicator to drop from 4 to 2 lines.

When I added coolant to the level just a little above middle between min and max, the "problem" disapeared...

The temperature indicator will never show an odd number of lines (1,3,5,7...) but only even: 2,4,6... It is written in the service manual as far as I can remember.
AFAIK when you heat the inside of the vehicle you extend the coolant's flow through the cabin heater (correct me if I am wrong) and indeed there is a drop in the coolant's temperature.

no, IllusiOn, when you turn on the heating, you controle only the air flow through the inside radiator... but the coolant flows all the time through the radiator, even during summer (this usually cause the inefficiency of the AC system on Logan)...

icatenej, I fully agreed with you... I tried to explain the same condition based behaviour of the heating system on the romanian forum, but many people still consider that is a "problem" somewere...

BTW. as we talk about all this issue, could you please tell us where this temperature sensor and it's connector are placed? I think that it could be valuable information.

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Dacia service personel and they said that this is normal behavior and that it happens becuase of cold air (in association with relaxed engine).


That is really right, I have same problem, It isn't a problem really.