hi,

Not sure if i should be concerned about something I've noticed my 2015 mk3 Scout doing recently. A few weeks ago i noticed that the coolant temperature dial behaving a little odd. It took a very long time (~20 minutes) to come up to 90 degrees, and while it was warming up the temp would go up and then down again. After around 20 min it settled in its usual place at 90 degrees C. I've had the car for 2 years and in all that time the coolant temperature has always come up to temperature very quickly and then sticks solidly at 89-90 degrees.

Now everytime the car starts from cold it takes around 15 - 20 min to come up to temperature. I'm pretty sure it used to take no more than 5 minutes.

 

Some more info.

Back in June, the water pump failed (after only 2 years!) and the coolant got pretty hot (although in the red zone) before i could turn the car off.

I had a new water pump and cam belt done.

The garage that repaired it said that the water pump had a small plastic bit broken off. They tried to find it in the pipework but couldn't - so presumably its in their somewhere! They showed me the fins of the pump and there was a little piece missing around 1 cm large.

 

Should i worry about it?!

Could that bit of plastic be blocking something and be the cause of the coolant temperature taking a while to come to temperature?

Could the time when the coolant got extremely hot have damaged another part that may the cause of the coolant temperature slow rise?

 

Any suggestions welcome.

 

Sounds like your missing bit of the waterpump might of found it's way to the thermostat and stopping it from closing off properly 

The most logical answer to this is that the foreign object is stuck in the thermostat, stopping it from closing. In that case, your engine will be trying to get up to working temperature whilst the whole cooling system is trying to cool it down...

thanks for the suggestion (i wondered if something like that might have happened).

If that is the case, it doesn't seem like a major problem. I guess i can stop worrying about it.

3 minutes ago, rangor_g said:

thanks for the suggestion (i wondered if something like that might have happened).

If that is the case, it doesn't seem like a major problem. I guess i can stop worrying about it.

 

Whereas it's not critical, you'll be using a lot more fuel whilst it's running like this. If access to the thermostat is easy, I'd fix it ASAP...

Likely a faulty thermostat very common on all VAG cars.

 

Bought a TT recently viewed 8 cars before buying one every single one needed the thermostat replaced.

 

 

My local garage has quote £240 (incl. VAT) to replace the thermostat. Seems a bit steep.

They say its less than hours work but the VAG thermostat only comes with housing and the whole thing is expensive (i guess around £150).

 

Can anyone advise on non-VAG parts? Any other brands i should look out for or avoid?

This is for a 2015 octavia mk3 Scout (so 4x4) 2.0 diesel manual.

@rangor_ghas your car a DSG, so the issue could be the 2nd thermostat / regulator.  Next to the DSG Oil Cooler.

I have the same issue with my 1.4 TSI engine.

 

For mine, I am pretty sure it is the 103 degree thermostat which is stuck open. For EA211, the thermostat is inside the water pump and the garage refused to change only the thermostat which is doable. They quoted me £240 for the labour and the water pump itself is £200. It is not that difficult to open the water pump and access the thermostats, so I am going to do it myself and replace only the faulty thermostat and probably some gaskets when the weather allows.

Edited 26 October, 20223 yr by Vahids

16 minutes ago, roottoot said:

@rangor_ghas your car a DSG, so the issue could be the 2nd thermostat / regulator.  Next to the DSG Oil Cooler.

No its not got a DSG

Mine's only just had a new water pump and belt fitted.

Where did you find the diagram you posted?

Mine is 1.4 TSI which is different from yours. It is from net https://skoda.7zap.com/en/cz/octavia/oct/2013-753/1/121-121003/#10

my Thermo**** stuck closed 3 weeks ago on way to work, (2.0 cr elegance 4x4 )  managed to get to my local garage by putting the heater on full warm and full power blower which kept the temp at 90. £58.20 for a genuine one, but its a bugger to get to as its under the inlet manifold which needs to come out. 

If the problem manifests itself again then it was not the thermostat but the far more likely water pump shrod sleeve.

 

Very rare for a thermostat to stick closed, rare but not impossible if the wax capsule has leaked.

On 23/09/2022 at 00:04, gsmdo said:

 

Whereas it's not critical, you'll be using a lot more fuel whilst it's running like this. If access to the thermostat is easy, I'd fix it ASAP...

 

Not on a diesel it wont, although at the time you posted the OP, like many, had not given out the important information of which engine his car has.

 

After the first 30 seconds of running a diesel has no significant additional enrichment, some of the heat energy will be lost to the overfunctioning cooling system but no more than keeping the heater on full, neither of which are measurable in MPG terms.

An update:

My local garage has replaced the thermostat, and now the engine is warming up in 10-15 min and sticking to 90 degrees as it used to. However, i only got to drive it once before i got a warning on the dashboard telling me to check coolant level. It had dropped to below the minimum. Fine, perhaps a bit of an airlock that had cleared after the new thermostat had been put in.

But, I also noticed that the coolant is thick and black. It looks extremely oily.

So, is this the oil cooler leaking oil into the coolant? or something worse? One independent VW garage i spoke with said it could be a head gasket problem? Doesn't sound good.

 

I'm going to book it back into my local garage for them to replace the oil cooler and flush the system.