Breezy_Pete

There seems to be an increasing list of insufficiently developed systems being rushed into production lately.

What's the sump, steel or ali?

Dealers make stuff up a lot.

@Midoutndoes your car have a petrol or diesel engine? You only really need to add anything to the cooling system if the level falls below minimum (when completely cold), and given your location I would suggest you would be fine just adding water if it does need a small top-up. Obviously if it keeps needing top-ups you will probably need to get some G12evo or whatever the next flavour of VW coolant is. But if it does you may also need to find the leak.

In carbs there's generally a much bigger pressure drop pre-to-post throttle plate due to the low pressure in the intake manifold, I would say, than at the venturi. Obviously not at, or close to WOT. Also a much smaller gap to obstruct with ice at low throttle openings.

Fingers crossed here.

As in "gonna have to start again", or "browsing ebay for secondhand" engines?

To be fair, moisture really needs to be involved, like sweat or screenwash on surfaces for true wind-chill to occur via latent heat of evaporation.

Why does a radiator have a fan then?

If you were to also flick the bonnet latch over after opening the bonnet (to make the microswitch in the latch register a closed bonnet) and before locking up and waiting 30 mins plus, you should see a proper 'asleep' reading. Not sure how much if any difference this makes. Would be interested to know if you fancy trying it? Remember to pull the bonnet release inside the cabin before trying to shut the bonnet afterwards though, otherwise it'll clang into the closed latch.

Yes, one of those tools will release the pins from the connectors. You may not need to do that though. The loom is probably designed to come out the other way, with all the bits to the right of your arrowed hole going through right to left? Not sure. Another thing to consider/investigate is how easy it is to remove the whole door. On Mk1 Fabias for example it's just the check strap, the A-pillar connectors and two 13mm 'nut-like things' to undo and then the door lifts off its hinges. Have an assistant though, especially when re-fitting, as the doors are obviously heavy. Once off you have far, far easier access. I can't see form your photo whether the hinge arrangement has this easy-release feature, maybe post a close-up of a hinge?

Yeah, good shout Keith. In fact the noise gets quieter when he goes to the dual clamp area, not louder.

The wire mesh once covered the whole corrugated (flexi) section, to keep little stones from getting trapped between the convolutions which might then puncture it, non-essential. The leak is probably at the dual sleeve clamp he points at at the end of the video, but may also be at the flexi. You'll have to ask. Relatively cheap to replace the front as there isn't a catalytic converter in that front section on the 1.2 engines, but there is a lambda sensor at the front end, so be careful with that if DIY'ing. There's a possibility that the leak has come about due to excessive engine movement fore-and-aft, this might result from a rear engine mount ("dogbone mount") that is allowing too much motion due to age/wear.

I have my doubts about that. There are some plastic ones to go with plastic sumps in some recent cars, but alloy? The washers on some might be alloy. Copper washer will be fine, it's an M14 thread, so something that'll fit over that and not crash into anything on the OD. Bog standard I expect. Check for leaks 1 hour and 1 day after fitting/torquing and you'll be fine.

Check that fuse 8 hasn't re-blown as a first step. My experience with VCDS suggests that once the refrigerant pressure sensor in the high pressure line reads 9 bar, the fans come on at low speed. If it then dips down below 6.8 bar, they go off again. And cycle on/off as reqd. If the pressure ever gets up to 16 bar, the fans switch to high speed (if they are both twin speed). Back down at 12 bar, from memory. 1 bar is approx 15 psi, so multiply those numbers by 15 to get psi.

My spare Polo (2005, BKY engine, with A/C) has only one rad fan, despite its cooling needs being seemingly identical to my 2003 BBY with A/C. I guess the single fan is probably slightly larger and maybe more powerful than the larger one in the dual fan set-up, but haven't checked. Cost cutting I guess? It does make the system less fault tolerant. When I acquired it, the low speed function on it was non-functional due to the 'traditional' burnout of the internal resistor, and high speed couldn't be triggered by radiator temperature because one of the thermoswitch wires had broken. I think it must have only been used for short local journeys, because it was very vulnerable to overheating in that state. A/C hadn't been fixed when reported empty several years ago according to service records. Reminds me, I have a couple of o-rings to change on that, which could be today.

I wonder if an incorrect sketch in Haynes is behind all this grief? I've just looked at our 2005 car and it looks nothing like that line drawing. I can't see any evidence of the part number having changed in the parts catalogue during production of mk1, so it seems it has never been like that illustration.

The charging system will still not charge it up fully even if you always disable S/S.

Ah, OK, good plan. There are two factors that might mean it's fine. The charging system on Start/stop cars actively avoids fully charging the battery. Measuring in circuit, unless you've gone to significant trouble to ensure the car is completely 'asleep', you will always see a lower voltage than if the battery is disconnected from everything and left for a while

What made you suspect it might be unwell? I mean before you did any investigation.

Just out of curiosity Ken, I had a look at some Octy 1 A/C circuits, and the fans' wiring appears to be parallel too. If yours work as you describe, there may also be a fault with low speed function in one or other fan, depending on which lefts and rights you meant.

No harm in trying it, but if they both came on with radiator getting hot, I'd expect them to both come on via the aircon action too, unless the A/C isn't working for some other reason.

Do both fans come on at low speed now when A/C is switched on?

I have no plans to, but appreciate the concern.

Man! You're absolutely determined to not let this discussion be about inline 4 pot engines, eh Root? There's an EV subforum, remember? If I want to read about EV tech, I'll go there.