Polo has died

[martynh]

An update:

We spoke to the VW service guys and they basically said they would try get VW to pay but the risk would be ours and we would be out of pocket if they declined.

We went and test drove a few cars on the weekend and the Mazda salesman was willing to take the Polo as is, think he was trying to hit his quota! So we got $10k for it (trade in range is 10.5-12.5) but have picked up a new Mazda 2 today so the headache is no longer ours

[Hail22]

Great outcome for you mate, that just proves how good Jap car brands / Ford / Hyundai and Kia are like compared to the arrogant and elitist attitude of VWAG.

[nomadx38]

You haven't been running 91 octane fuel have you? Mines done 95,000km and countless track days and the engine is still going strong, bar the slight bottom end knock when it's hot. To blow a piston in one of these is pretty hard.

[bluey]

So what are the most common causes of premature loss of compression in a not-very-old VW?

Wouldn't a turbo failure be more likely than a ring failure?

[nomadx38]

These cars are pretty low pressure as far as boost goes so really it's not the turbo that will go. Having said that the Pistons/rings/rods or bearings aren't likley to give way either as it's not a real stressed engine (haha it's only a sohc 8 valve sadly).

But like all vw cars they have to be run on 95min octane (really 98min in summer) to prevent knocking which it will do with a 10:1 compression ratio added with boost - which destructively destroys every internal part of an engine which is where these problems start - and for what to save 4c P/L pathetic

[bluey]

Sounds like the petrol grade misfuelling problem is just as bad as trying to put petrol in a diesel.

Isn't the knock sensor meant to protect from low octane fuel (at the presumed expense of poor efficiency and performance)?

I thought I read the SOHC and 8 valves was to reduce internal friction, thus improving efficiency. And the turbo takes care of the breathing. I presume they ran it up on some fancy computer model.

[nomadx38]

Sadly no the 8v is just to cut costs. Dohc is better for air flow any way you look at it both mid and up high. But by doing this that can use up old parts such as the old school HT leads and side mounted spark plugs instead of the new revised 1.2L (which is based off the 1.4L) which has 4 valves and more efficient and reliable coil on spark packs which is centrality positioned.

Also the knock sensors are designed to retard performance in the event of a "knock" but a knock has to occur first for it to detect this. As such with enough time it will do damage. Also if the fuel rating is so poor that it's constantly knocking it will just continiue to run the engine in its most retarded state as it's not allowed to stop the engine altogether for obvious safety reasons.