Engine temperature won't go above 55, no matter how far I drive the car. This is a 1.4 tsi 103 kw Octavia with EA211 engine. At first it only went up to 85 degrees, then only 75, then only 60 and now it doesn't go above 55, in fact, it jumps back to 50 from there. Both thermostats have been replaced, but the problem hasn't gone away. Any ideas?
 

Hello, welcome to the forum.

Is the engine really running cold - has the actual engine temperature been checked independently?

What is the oil temperature reading? (if you have Maxidot display)

Do you have normal hot air or just lukewarm?

4 hours ago, Warrior193 said:

Hello, welcome to the forum.

Is the engine really running cold - has the actual engine temperature been checked independently?

What is the oil temperature reading? (if you have Maxidot display)

Thank you, I'm glad to be here! 
Unfortunately, I have the dumbest display. I can't even check the consumption. I want to connect an OBD to it, but I don't have it at hand at the moment. The 2nd thermostat was replaced last night and everyone was sure it was the fault, so it was not checked electronically. I checked the temperature of the pipes manually and knew how to hold the pipes with my bare hands, even though I didn't only use them in the city.  While driving, I noticed that it doesn't blow as hot unless I drive at 90. In the city or when slowing down, it drops from 55 to 50. It always blows hot, but sometimes not evenly, even though the temperature is set to maximum.

 

2 hours ago, ords said:

Do you have normal hot air or just lukewarm?

Sometimes lukewarm, sometimes hot. It depends on the speed.

It sounds like you need to plug in the OBD reader to check what is happening with fluid temperatures. Can your reader display live data?

3 minutes ago, Warrior193 said:

It sounds like you need to plug in the OBD reader to check what is happening with fluid temperatures. Can your reader display live data?

I think so. It's a little old, but I think it shows. I'm planning to get an OBDEleven now. I won't be able to access the OBD until the beginning of next week.

On 14/02/2025 at 18:13, Warrior193 said:

It sounds like you need to plug in the OBD reader to check what is happening with fluid temperatures. Can your reader display live data?

Well, I managed to read the car. Then I read that I drove 25 km with it.

If the main thermostat works it is hard to believe that the car does not heat up. Have you tried with your hand that the thermostat is and radiator are cold after driving? (dont hurt your fingers with the fan).

 

Otherwise I wud suggest that the temperature sensor gives faulty readings. Try to check in morning before driving what the scan tool says for coolant temperature and is it close to outside temperature?

 

However, if the temp sensor is faulty and coolant is hot, one wud expect hot air to cabin, except if the car wont let you draw heat from 'cold' coolant by controlling air flaps to heater matrix. Or you cud simultaneously have blocked heater matrix but that wud be unlikely.

1 hour ago, Skodaudi said:

If the main thermostat works it is hard to believe that the car does not heat up. Have you tried with your hand that the thermostat is and radiator are cold after driving? (dont hurt your fingers with the fan).

 

Otherwise I wud suggest that the temperature sensor gives faulty readings. Try to check in morning before driving what the scan tool says for coolant temperature and is it close to outside temperature?

 

However, if the temp sensor is faulty and coolant is hot, one wud expect hot air to cabin, except if the car wont let you draw heat from 'cold' coolant by controlling air flaps to heater matrix. Or you cud simultaneously have blocked heater matrix but that wud be unlikely.

It's all very strange. I'll try replacing the water temperature sensor. 
The engine warms up to 50-55 degrees relatively quickly, but it doesn't go higher, although yesterday morning it went up to 65-70 degrees, but in a split second it dropped the water temperature back to 50 and didn't go higher. This morning it was -7 degrees and it was still warm blowing into the passenger compartment at a water temperature of 50 degrees. 
And about the water temperature sensor problem, I just heard that the engine overheats. Anyway, I'll replace it and see how useful it is. 
I'll add that the car doesn't eat either oil or water.

From that indicated 127 f from the OBD, it does seem that the engine is running cold - unless the sensors are faulty and sending low readings to the ECU. Are you able to take a temperature reading of cylinder head with (say) an IR thermometer?

If head temperature is broadly similar to the one from the OBD, the only way I can see engine temperatures remaining as low as indicated is the thermostats remaining open all the time (or the cooling fans running constantly) - even then, the engine should eventually reach normal temperature.     

6 hours ago, charsstone said:

yesterday morning it went up to 65-70 degrees, but in a split second it dropped the water temperature back to 50 and didn't go higher

 

That is implausible, physics say that cannot have happened, either the temperature sender or its wiring connections are is faulty, it can be tested with a multimeter removed from the car with the probe immersed in water being heated in a pan if you want to be 100% sure before buying a new one.

 

 

1 hour ago, Warrior193 said:

From that indicated 127 f from the OBD, it does seem that the engine is running cold - unless the sensors are faulty and sending low readings to the ECU. Are you able to take a temperature reading of cylinder head with (say) an IR thermometer?

If head temperature is broadly similar to the one from the OBD, the only way I can see engine temperatures remaining as low as indicated is the thermostats remaining open all the time (or the cooling fans running constantly) - even then, the engine should eventually reach normal temperature.     

Unfortunately, I don't have an IR thermometer, but if the water temperature were around 90 degrees, I wouldn't be able to touch the water pipes with my free hand, would I? 

I checked to see if the cooling fan was spinning, but it wasn't, even though I revved the engine.

I wouldn't think you'd normally be able to hold a pipe for more than a second at 90C.

19 minutes ago, J.R. said:

 

That is implausible, physics say that cannot have happened, either the temperature sender or its wiring connections are is faulty, it can be tested with a multimeter removed from the car with the probe immersed in water being heated in a pan if you want to be 100% sure before buying a new one.

 

 

Well yeah, I probably will. We have now found a water pump number 0 392 023 211. How much does it have to do with water cooling?

1 hour ago, Warrior193 said:

I wouldn't think you'd normally be able to hold a pipe for more than a second at 90C.

Well, I don't know. I haven't touched the water pipes of the cars after 20-30 km, but logically, if it's at operating temperature, I wouldn't be able to touch it much, but I'm not experienced. 
Now I looked at the old thermostats to see how they behave in hot and cold water. I'll be honest, I have no idea how it's supposed to work. I couldn't find an exact description of it. The ones we put in are not of poor quality either. One is a Behr, the other a Meyle. 

Just now, charsstone said:

Well, I don't know. I haven't touched the water pipes of the cars after 20-30 km, but logically, if it's at operating temperature, I wouldn't be able to touch it much, but I'm not experienced. 
Now I looked at the old thermostats to see how they behave in hot and cold water. I'll be honest, I have no idea how it's supposed to work. I couldn't find an exact description of it. The ones we put in are not of poor quality either. One is a Behr, the other a Meyle. 

The second is placed in warm water, the first picture is placed in cold water. This is the thermostat that opens at 87 degrees. The pecs came out, but nothing else moved. After the hot water, we put it in the cold water, but nothing happened.

Warm water or hot? You called it both.

 

You really need to bring it to the boil to see it open fully, 87° is the regulated temperature at which it will barely be open.

 

What is/are "pecs"? A typo?

1 hour ago, charsstone said:

Well yeah, I probably will. We have now found a water pump number 0 392 023 211. How much does it have to do with water cooling?

A faulty water pump can cause overheating - I cannot see any way it could cause engine to run too cold.

13 hours ago, J.R. said:

Warm water or hot? You called it both.

 

You really need to bring it to the boil to see it open fully, 87° is the regulated temperature at which it will barely be open.

 

What is/are "pecs"? A typo?

We put it in boiling water. Under "Pecs" I feel the little metal rod sticking out of the top. It should slide out with the heat, right?

12 hours ago, Warrior193 said:

A faulty water pump can cause overheating - I cannot see any way it could cause engine to run too cold.

Doesn't this TSI engine have some kind of hidden thermostat? I've looked through several diagrams, but I haven't found anything that I didn't already know was there.

I am struggling to follow your somewhat incoherent postings.

 

The two photographs, are they of the same thermostat or the two different types?

 

Are they first one cold second one hot, warm, or boiling?

 

Both photos look exactly the same and look to me like the fully open position, I think I can see wear marks that witness that. So if one was taken in cold water and the other in hot water then the thermostat is jammed open.

18 hours ago, charsstone said:

The second is placed in warm water, the first picture is placed in cold water. This is the thermostat that opens at 87 degrees. The pecs came out, but nothing else moved. After the hot water, we put it in the cold water, but nothing happened.

 

Even more confusing, was the cold water photo taken before or after it was placed and photographed in hot/boiling water?

 

The thermostat should have retracted fairly quickly going from boiling to cold water.

4 minutes ago, J.R. said:

 

Even more confusing, was the cold water photo taken before or after it was placed and photographed in hot/boiling water?

 

The thermostat should have retracted fairly quickly going from boiling to cold water.

Okey, sorry. 

In both pictures, it's the same 87-degree thermostat. First, I put it in boiling water. Then the metal pin at the top came out. You could see it moving outwards. Then I put it in cold water, but nothing happened, it didn't move. Here, it was already suspicious that it wasn't working properly. I've now found a video explaining how the thermostat works, so that's clear. I replaced it with another one, a Bher brand, but nothing changed. Then the internal thermostat, which is behind the water pump, was also replaced with a Meyle brand, but no change, the water temperature still shows 50 degrees. It would be strange if the new thermostats were exactly the same bad. There is no error code. All I can do is open the thermostat again and test the new ones in boiling water. (By the way, if you hover your mouse over the image, it will display the link address at the bottom left or right and say "hot.jpg" or "cold.jpg". It would have been better if I could put the images side by side, but that's how it works.)

On 18/02/2025 at 10:22, Skodaudi said:

Have you tried with your hand that the thermostat and radiator are cold after driving? (dont hurt your fingers with the fan).

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