2 hours ago, nta16 said:

What is BTB?

https://en.wikipedia.org/wiki/Bromothymol_blue

2 hours ago, D.FYLAKTOS said:

But you had that problems few years ago.

So what's next? We must change the radiator switch to 85-90 'C?

If i remember correct the factory in mine was 87-92 'C.

early HGF as I was saying and later proved right

On 25/06/2025 at 13:02, Thefeliciahacker said:

The cooling SYSTEM performs better the hotter it is

So what's next? We must change the radiator switch to 85-90 or 90-95 'C?

If i remember correct the factory in mine was 87-92 'C.

8 minutes ago, D.FYLAKTOS said:

So what's next? We must change the radiator switch to 85-90 or 90-95 'C?

you have the 2speed fan control or the single speed?

43 minutes ago, Thefeliciahacker said:

you have the 2speed fan control or the single speed?

I have a/c and two speed radiator fan.

19 hours ago, Thefeliciahacker said:

if tested with BTB, will show signs of early-stage HGF

Opposite I know but something to add to your finding (after checking of course) I have experience where a coolant containing a PH colour indicator hasn't shown up the early stages of HGF, it may be that the threshold for show hadn't been reached but to me that's a false negative if you were relying on this alone.

3 hours ago, D.FYLAKTOS said:

I have a/c and two speed radiator fan

does coolant temp activate both fan speeds (2 prong or 3 prong thermoswitch)

3 hours ago, nta16 said:

Opposite I know but something to add to your finding (after checking of course) I have experience where a coolant containing a PH colour indicator hasn't shown up the early stages of HGF, it may be that the threshold for show hadn't been reached but to me that's a false negative if you were relying on this alone

Maybe it has picked up alkaline material, and the weak carbonic acid couldn't turn the indicator

25 minutes ago, Thefeliciahacker said:

does coolant temp activate both fan speeds

(2 prong or 3 prong thermoswitch)

At Green dot and extremele rare.

https://www.briskoda.net/forums/topic/512393-cooling-system-problem-again-in-my-felicia/page/4/#findComment-5950995

Mahle with 2, here is an example:

https://i.ebayimg.com/images/g/NPMAAOSwl7Fm6yfy/s-l400.jpg

i never had 3 prone in my Felicia, never saw one in the market.

1 hour ago, D.FYLAKTOS said:

Mahle with 2, here is an example:

https://i.ebayimg.com/images/g/NPMAAOSwl7Fm6yfy/s-l400.jpg

i never had 3 prone in my Felicia, never saw one in the market.

So you have the ALEX AC with the cut 1st speed, great, ideal candidate for my circuitry.

The ALEX AC system has 2 speeds
Speed 1 is controlled by AC

Speed 2 is controlled by AC (high refrigerant pressure) and the thermoswitch

12 minutes ago, Thefeliciahacker said:

So you have the ALEX AC

Yes, i have said that in the past

https://www.briskoda.net/forums/topic/491645-can-i-make-a-modification-to-my-felicia-13-filter-case

https://www.briskoda.net/forums/topic/526164-question-felicia-13-mpi-alex-hvac

plus the story of the owner (is in israel) because one of the Skoda mechanics from the official dealership (where i bought the car) had travelled there for a/c seminar-tour in the factory etc.

Your radiator switch is 80-85,85-90,90-95 'C ?

78-87, 85-92

18 hours ago, Thefeliciahacker said:

Maybe it has picked up alkaline material, and the weak carbonic acid couldn't turn the indicator

I can't prove this wasn't the case but I very much doubt it as the the long life coolant unfortunately for me was changed or refreshed frequently at fractions of its expected life service and I'm quite thorough with initial coolant changes - flush, clean, flush/back-flush/flush of heater matrix, rad and some hoses and pipes out of car, engine block in situ. As it's devil for weep-leaking the stat housing and stat (both have bypasses) may stay on the cylinder head (same to for heater tap).

If you notice the early signs of HGF that's very good as I've always only noticed with the benefit of hindsight on my own cars ( possibly just mentally avoiding yet another car problem with the many, many, many, kindly given to me by people in the English motor trade and parts quality from China and English specialists. My wife is much better at spotting and identifying problems than me , she remembers them from previously, I think I must shut out such memories for the sake of retaining some sanity. 🙃

Edited 29 June, 202529 Jun by nta16

On 28/06/2025 at 23:13, Thefeliciahacker said:

78-87, 85-92

You had 78-87 'C and now installed 85-92 'C?

6 hours ago, D.FYLAKTOS said:

ou had 78-87 'C and now installed 85-92 'C

first and second speed

I am on vacations, new measurements and photos soon.

I will make a comparison betwwen the gauge indication and the console (coolant) thermometer, snapshots from the highest gauge indication plus fuel comparison measurements.

Apology: i have done a mistake in posting, i forgot to mention that from the point of 94969 Km i have changed the G12 Plus with the good-old G12 so any MPG results from this point

https://www.briskoda.net/forums/topic/512393-cooling-system-problem-again-in-my-felicia/page/3

till today are with G12, so any comparisons from now on are: G12 HEPU and old radiator vs G12 HEPU and new radiator.

So i had: 95297 Km and i had 21 litres which means from the 94976 Km i have travelled 321 Km distance (according to the Trip meter is 321,1) the Total fuel consumption was 6,54 ltr/km or 43.19 British MPG and the trip begins, after refuelling the Odometer indication is 95301 Km (324,8 in the Trip meter) Total consumption 21.5 litres and Average is 6.6 (or 42.80 British MPG).

The next measurement was in 95375 Km, i have also manage to take photos from the highest point of coolant temperature at 95640 Km and i will compare it with the indication of the console thermometer.

(to be continued)

An unofficial comparison of what the cluster gauge shows and what the aftermarket in the console (it's sensor is after the expansion tank's hose to the radiator).

and

The photos are taken immediately when i stopped the car.

As you can see they don't match.

Refuelling, TC-6 is zeroing and the trip begins, Odometer indication is 95301 Km (324,8 in the Trip meter), at the first stop:

Now the Odometer indication is 95375 Km (74,8 in the Trip meter), the distance was 74 Km in Highway and the Total consumption is 4.4 litres which is Average 5.94 ltr/Km or 47.56 British MPG.

The Ø indication on the TC-6 agrees.

Keep in mind that the car had: 2 persons, 2 valises, 3 sport bags and a full fuel tank so with that weight i find the Fuel Consumption that hot summer day as Very Good.

The next measurement is after a Mountain Route (lot of curbs in an uphill and then downhill) till final destination at noon.

On 16/07/2025 at 12:22, D.FYLAKTOS said:

The photos are taken immediately when i stopped the car.

As you can see they don't match.

EXACTLY AS I'VE SAID.

90C is way higher than the midline on the gauge as reported by ECT sensor

On 16/07/2025 at 12:22, D.FYLAKTOS said:

also your alternator is getting weak

2 hours ago, Thefeliciahacker said:

also your alternator is getting weak

The car is off, below the digital meter says 13,13 volt.

13 hours ago, Thefeliciahacker said:

EXACTLY AS I'VE SAID.

90C is way higher than the midline on the gauge as reported by ECT sensor

I can not rely 100% on the factory cluster gauge but on the other hand the aftermarket on the central console isn't something expensive as a GReddy or AEM.

95456 Km (155,3 in the Trip meter) so the distance was 81 Km in Mountain Roads.

Keep in mind that the car had: 2 persons, 2 valises, 3 sport bags and a 3/4 full tank in a hot sumemr day.

The Total consumption is 9,4 litres which is Average 6,06 ltr/Km or 46.61 British MPG (Excellent result) 🤩

The Ø indication in the TC-6 agrees.

Ah okay sorry