On 22/06/2025 at 22:33, Thefeliciahacker said:

First speed is between 95-97 deg.

Second speed 101-103

Why there is a benefit for an old design engine to work in such a higher temperatures?

20 years back the French cars had the reputation that must do this to perform properly, i don't know if that was true or a rumour.

12 minutes ago, D.FYLAKTOS said:

Why there is a benefit for an old design engine to work in such a higher temperatures?

It has to do with fuel consumption AND letting the cooling system perform better you know grater ΔΤ greater ΔQ

33 minutes ago, Thefeliciahacker said:

It has to do with fuel consumption AND letting the cooling system perform better

you know grater ΔΤ greater ΔQ

The coolant performs betetr over 100 'C?

"γουατ αρε δηζ;"

2 hours ago, Thefeliciahacker said:

I am not good-looking I look like Shrek

In that case one less thing to worry about in life. 😄 You seemed alright to me in your video(s). I usually put that I've kept my teeth, looks and modesty but don't mention what those looks were and are like, and no one has taken the modest hook either.

1 hour ago, nta16 said:

I usually put that I've kept my teeth

Teeth are very important i have perfect teeth to this day, no cavities to speak of, guess not drinking sugary drinks does good

On 21/06/2025 at 21:51, D.FYLAKTOS said:

95050 Km ..... so fuel consumption % was 6,08 ltr/km or 46.46 British MPG (excellent).

I have found the photo of Average fuel consumption, it's almost identical to Total so the calibration is OK.

@Thefeliciahacker The coolant performs betetr over 100 'C? How?

1 hour ago, D.FYLAKTOS said:

The coolant performs betetr over 100 'C? How

The cooling SYSTEM performs better the hotter it is
I will put it simply.
If I want to dissipate 50 kW and I am using forced convection, I will either need more airflow or a higher ΔT.

In my case, I decided to let the rad get hotter so I can increase the heat transfer and NOT need the fan all the time.

You reach a point, especially in summer, where your temperature difference is not sufficient for transferring the amount of heat you need. And you end up compensating by increasing airflow. I let my colant get hotter, get my heat transfer without the need of the fan, there is no point in having a 90% duty cycle on the poor fan.

I have in summer traffic a less than 40% duty cycle on the first speed, and most importantly, less than half of the motor startups.

Edited 25 June, 202525 Jun by Thefeliciahacker

The first line is where the thermostat fully opens

The second line is where the fan will kick on

And on the middle grey line is where theoretically the second speed would initiate.

So yes, I got over the worry about Felicia's temp.

I let it heat up and let my new rad do its job.

I only worry above the middle grey line, which I haven't gotten to till this day. Soooooo.....

Edited 25 June, 202525 Jun by Thefeliciahacker

Back to shcool,i left the desk in the middle of the 80's but now we have Google search.

..................................

In coolant systems, ΔT (delta T) represents the temperature difference between two points, typically the inlet and outlet temperatures of the coolant. It's a crucial measurement for assessing the efficiency of heat transfer within the cooling system.

Temperature Difference:

ΔT is calculated by subtracting the lower temperature from the higher temperature.

Cooling System Efficiency:

In a car's cooling system, a larger ΔT might indicate that the radiator is effectively removing heat from the engine coolant. Conversely, a smaller ΔT could suggest a problem with the radiator or other components, preventing proper heat dissipation.

Monitoring and Diagnostics:

ΔT is a key indicator used in diagnostics to identify issues like a faulty thermostat, a clogged radiator, or other cooling system problems.

What about ΔΤ between the rad and ambient air

23 hours ago, Thefeliciahacker said:

The first line is where the thermostat fully opens

The second line is where the fan will kick on

And on the middle grey line is where theoretically the second speed would initiate.

Tomorrow i will post mine, are different than yours.

I can have some measure for the coolant temperature but after the expansion tank, before the thermostat the experiment failed (i have posted photos in the past).

Also i can have from the engine bay plus in the ''air cabinet'' filter area.

@Thefeliciahacker @D.FYLAKTOS What you have just proved is that Felicia temperature gauges are not truly calibrated. Time to spike this thread maybe?

No need for new, we are good here.

1 hour ago, Paws4Thot said:

What you have just proved is that Felicia temperature gauges are not truly calibrated

Indeed nowhere near close

5 years before i posted about this with phtos and somewhere i have posted a video too.

The gause on the cluster was showing false indications due to detritus on the lower part of the coolant sensor, i also have posted a depiction of this somewhere in the forum.

I found it by personal search.

City Traffic: The temperature rises, the thermostat open for 1st time and the needle drops to the Yellow dot.

The driving continues, the needle rising, stays for long time in the white factory line and in Summer after some time reaches the Blue dot and the fan start spinning for a while.

The meddle drops and if i stay in traffic for long time then again the above.

From a recent trip, Highway at noon.

The latest months only one (1) time i saw the needle to reach the Green dot, was in a Mountain Route in the top of the uphill with thinner air but after a while dropped.

Was 2023 (old radiator and G11) when after a trip involved in a hard City Traffic and in a red light i saw the needle reaching that green dot but after the radiator fan stopped return to normal.

I have seen the needle in the 100 'C but that was 5 years ago with lot of problems back then, since that time never again.

Edited 28 June, 202528 Jun by D.FYLAKTOS

On 25/06/2025 at 12:21, Thefeliciahacker said:

The first line is where the thermostat fully opens

The second line is where the fan will kick on

And on the middle grey line is where theoretically the second speed would initiate.

So yes, I got over the worry about Felicia's temp.

I let it heat up and let my new rad do its job.

I only worry above the middle grey line, which I haven't gotten to till this day. Soooooo.....

Imo this is how it should be, assuming that the bottom red line is 90°C. Felicia has working temp at 90°C to reduce heat losses and there's no reason to run 80° thermostat from the older Skodas.

FYI, on a 1 speed fan, which has lower power and covers smaller area than your 2 speed one, the stock setting is 97° +-3 - somewhere around your 2nd speed. Either to reduce fan's duty cycle, increase delta, or both. That's what Skoda deemed acceptable, so if engine operates within these conditions, it should be fine. Personally, I didn't like it and fit 80° thermoswitch from Skoda 120, which resulted in similar operation to yours (without the 2nd speed)

Edited 27 June, 202527 Jun by Papez

there's no reason to run 80° thermostat from the older Skodas.

I don't think that anyone has an 80 'C thermostat, those for Felicia in the market are 87-88 'C.

An example:

https://kritosparts.gr/SKODA-FELICIA-II-(6U1)-01-98-06-01-1.3-AMH-(68hp)-01-98-06-01/Thermostatis

3 hours ago, D.FYLAKTOS said:

I don't think that anyone has an 80 'C thermostat, those for Felicia in the market are 87-88 'C.

An example:

I think he wanted to say thermoswitch from what I recall

4 hours ago, Papez said:

That's what Skoda deemed acceptable, so if engine operates within these conditions, it should be fine

It is, the HGF, after so many years, we have concluded is always attributed to corrosion OR EXTREME overheating (i.e. coolant loss).

With normal temps, the HG of the felly will not fail... EVER

And the corrosion can be attributed to improper coolant and infrequent coolant changes.

From my exp people don't use good coolant and then start losing coolant due to starting HGF and they add back either distilled water or very cheap coolant and then everything goes to heeeelllll.

Well, in Greece, almost 90% of Felicias, if tested with BTB, will show signs of early-stage HGF, so people start lowering thermoswitch temperatures, installing secondary fans, etc. Instead of directly addressing the issue. I perosonally have a 6th sense of HGF.

On the grande punto, i could tell the HG was about to fail around 8 months before my father's technician accepted it. All that without testing it with BTB. WHEN I GOT ANGRY I used BTB in front of a whole workshop, proving the guy that was swearing it had a healthy HG that in fact IT DID NOT.

Suddenly, the kiddo got some respect.

I may be doing a last video de-mystifying the SKODA OHV engine regarding HGF and all the misconceptions cultivated over the years. And it will be done in GREEK and in English.

Edited 27 June, 202527 Jun by Thefeliciahacker

29 minutes ago, Thefeliciahacker said:

in Greece, almost 90% of Felicias, if tested with BTB

I used BTB in front of a whole workshop

Google search: BTB test stands for bovine tuberculosis test.

1 hour ago, D.FYLAKTOS said:

bovine tuberculosis test

I aint no doctor yet

Since we didn't clarify what was the ''BTB'' that @Thefeliciahacker use...

15 hours ago, Thefeliciahacker said:

With normal temps, the HG of the felly will not fail... EVER

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.

15 hours ago, Thefeliciahacker said:

if tested with BTB

What is BTB?

1 hour ago, nta16 said:

What is BTB?

In the only expansion I've ever heard of it is "Back To Base", so returning a Skoda to Czechia.