Hi all. Looking for some suggestions as to the cause of a problem we experienced with our 2014 Octavia Estate 2.0TDI this morning, please.

 

Driving along normally at 60 mph along an A road and the coolant temp. dial whipped round to 130 degrees and the red space and a the "Coolant over-heating, STOP" message appeared on the display screen.  We did so as soon as it was safe.  I opened the bonnet expecting to feel the excess heat, the sound of the fan spinning and to feel the coolant reservoir hot to the touch.  Didn't observe any of these things....  Out of curiosity, I carefully unscrewed the coolant reserve lid (remembering it's pressurized and that it was likely to be hot) a couple of turns to release the pressure which was there.  The liquid bubbled a little around the cap and some spilled out but it was luke-warm, no more.  I had only waited a few minutes since opening the bonnet so don't know why the coolant was not hot.  There was also plenty of it with the reservoir still filled to the minimum line even after some had bubbled out.

 

Fan still not activating at this point.

 

We then checked the oil and it was bang in the middle of the dipstick range.  After about 20 minutes of waiting, we started the car and gently drove it home at sensible speeds and the temp gauge staid at the 90 degree normal level and there were no more warning messages.  We took the same route.  Back at base, I checked the fuses (FYI our owners' manual does not list the radiator fan amongst the powered items so checking online, I found that it's number 4 in the engine bay compartment with the coolant pump number 7).  Both of these were OK.

 

So, could it be a malfunctioning sensor perhaps?  Or a knackered fan?  Looking for hints as we have a long trip planned in 10 days which we won't make if this isn't sorted 🙂

Cheers for now

UF

Edited 3 November, 20223 yr by unionfan

I would try to get fault codes read, there may have been a short on a wire/loss of signal that made the car go into "SAFE" mode and put the fan on as safety (because it was unable to read temperature?)

From what you have said it would seem that you might have the dreaded water pump problem. suggest you read the sticky thread at the top of the page, it's a long read.

15 hours ago, unionfan said:

So, could it be a malfunctioning sensor perhaps?

Or neither; as per @daftbugga I'd suspect the water pump issue and add that you'll also find threads about it on the Superb 2 and 3, Kodiaq, and possibly Kamiq and Koroq fora.

4 hours ago, KenONeill said:

Or neither; as per @daftbugga I'd suspect the water pump issue and add that you'll also find threads about it on the Superb 2 and 3, Kodiaq, and possibly Kamiq and Koroq fora.

+1

11 hours ago, daftbugga said:

From what you have said it would seem that you might have the dreaded water pump problem. suggest you read the sticky thread at the top of the page, it's a long read.

Hi and thanks daftbugga but there's no sticky post at the top of this page in my view???  Happy to read anything that might help and want to be sure to get the right post 🙂

 

8 minutes ago, unionfan said:

Hi and thanks daftbugga but there's no sticky post at the top of this page in my view???  Happy to read anything that might help and want to be sure to get the right post 🙂

It's at the top of the Octavia 3 forum opening page here

Edited 4 November, 20223 yr by PetrolDave

8 minutes ago, unionfan said:

Hi and thanks daftbugga but there's no sticky post at the top of this page in my view???  Happy to read anything that might help and want to be sure to get the right post 🙂

 

https://www.briskoda.net/forums/topic/453298-the-mk3-octavia-tdi-water-pump-thread/

 

I think this is the sticky thread being referred to.

Thanks all. Going to share this with my mechanic today and see what the plan is 🙂

UF

 

If it happens again it may well be worth parking up somewhere safe & rather than checking anything just sit there with the engine running, if the coolant temp drops almost as fast as it rose it's a fair indication that it is the water pump.

I had it happen on my last octy something like 10 times, every single time the temp rose from 90 to 120/130 fast & then dropped back to 90 almost as fast. 

Modern VAG temperature gauges are very misleading, they will show 90 when the actual value is 77 and still show 90 at a real 116 but then when the real value hits 117 the gauges shoots up to a ridiculous value. The effect of this is in 99.95 of cases people do not fret and obsess about the minuti of the gauge readings as they used to with observations like "it just reads over 90 and then just under" so it just sits there reading 90 and no one notices or cares which is what VAG want. BUT if you do get an issue such as the electronically controlled cam belt driven water pump failing, the real temp goes up and up to 100 or more but until it becomes a major issue, you don't know. Then when it hits 117 (and I have logged this), the gauge goes goes FSD and the dash goes crazy scaring the **** out of you; personally I would prefer an accurate gauge, forewarned is forearmed.