Hi guys.

I've just spent the best part of an hour googling this. Been on VW Vortex, uk-polos, and club polo looking at what causes this and the only thing I can find is the breather pipe might need replacing, but no definitive answer.

6n 1.4 8v APQ

The breather pipe hasn't got much mayo on, which usually seems to be the case, but as you can see the throttle body itself is absolutely covered in oil, and so in the inside of the airbox and the air filter.

The breather pipe has gone soft and collapsed but there are no obvious holes that I can find.

It looks like (what I think is a valve) in the airbox has died?

So maybe this is at fault? Although I was of the understanding that this pipe was supposed to be vacuum towards the crankcase?

Any help with this would be greatly appreciated. Cheers in advance.

Edited 24 August, 201412 yr by sleeds

If that valve is designed to open at high pressure, and instead it is now open all the time, it would cause the problem you're having.

A replacement airbox should be dirt cheap so it's worth a go. If not, you could have very high oil pressure. This is pretty unlikely though, as you'd have a warning light/buzzer going off.

Cheers for the reply.

Whilst I'm asking questions, would there be any issue with re-routing the breather to a catch can and just plugging the breather hole in the airbox?

On my mk2 I have a standard breather canister with the pipe looped back down out of the way, and te airbox hole plugged up.

I'm not too sure on the breather layout on 6n's. You may want to get a new breather if you wanna do the same as me though. If it continues to spit out oil, you'll fill the can very quickly!

Best to properly sort the problem first really.

Excessive crankcase pressure is what will cause this sort of problem, absolutely nothing to do with "very high oil pressure".

Crankcase pressure is caused by blow-by past the pistons and even on a new engine, there will be a small amount of this. The actual PRESSURE is the result of the blow-by being unable to escape, so it DOES NOT necessarily indicate that your engine is worn out, it could simply be that the oil separator is blocked (the box like object that the breather hose, shown in your photograph connects to)

It can be a bit of a pig to remove the old one, as you need a universal joint half way down your arm! but you can get them out.

Suggest that you replace said oil separator, rather than than try to clean it, fitting a new breather hose as you put it back.

The little valve that you have pointed out, is, as you say, intended to keep a lower pressure in the crankcase (You can hardly call it a vacuum), but as this is on the engine side of the air cleaner element, it could be dodgy to try and fabricate a new one, although it is 'only' polythene, if it isn't attached securely, there is a chance that the engine could swallow it, should it become detached.

A new complete air cleaner might be the best option, unless the valve will respond to a good clean up.

A catch-can is, of course another option, but if the oil separator is blocked (or even IF you have excessive blow-by from the pistons) you will be emptying it pretty often.

Regards

@caretakerplus.

you say oil pressure has nothing to do with it but if you had a oil pressure gauge installed and the crankcase blow by increases.

does that not mean it is trying to escape and therefore can pump oil out of the breather.

then doesnt that mean the oil pressure gauge would show a higher reading?

damunk.

Sorry, I don't follow what you are saying here at all.

The FLOW of oil is created by the oil pump.

The PRESSURE of the oil is created by resistance to that flow - for example, due the close running clearance between crank pins and big end bearings - An oil pressure gauge would be installed in the feed out of the pump, so whatever pressure existed in the oil circuit, it would register on the gauge.

Maximum oil pressure is regulated by a relief valve on the oil pump.

In the unlikely event of the pressure going way too high, you would probably find oil leaking from such places as the crankshaft and camshaft oil seals.

When the oil has finished its 'rounds' in the engine, it returns to the sump ready to be recirculated.

Under normal conditions, there would be hardly any positive pressure in the crankcase, and even if there were, the oil pressure gauge would be unable to detect this - As I said, the gauge is in the feed side of the oil circuit, it is NOT being supplied from the crankcase.

Regards

As I said, the gauge is in the feed side of the oil circuit, it is NOT being supplied from the crankcase.

Regards

So lets say all cyclinder rings were worn and combustions produced loads of blow by gas. Isn't that pressure in the engine therefore increasing oil pressure? That's what I meant.

Sorry! The answer is 'No'.

If you were sat in the bath, the water pressure in the bath would be minimal, but the pressure in the pipework leading to the taps would be much higher.

If we were to connect a pressure gauge to that pipework, it would tell us what the pressure of the water in the pipe was.

If we now turn 'on' the tap, the pressure in the pipe will fall, remember that we said that pressure was created by the resistance to flow, well, now there is hardly any resistance, as the tap is wide open, the pressure registered on the gauge will fall, but the pressure of the water in the bath will not increase, save by the weight of water now residing in the bath.

However, if we were to seal over the bath (preferably NOT with you in it ) and continue filling the bath with water, the rising water level would compress the air above the water level, this is something akin to having a blocked crankcase breather.

This is perhaps not the best of analogies, as the flow of the water is created by forces outside of the bath, whereas in the engine, the oil pump is self contained within the engine.

If there is loads of blow-by in an engine and the crankcase breather happens to be blocked, a mixture of oil and combustion product will find its way out at the weakest point, but the pressure of the oil in the oil galleries etc (equivalent to the baths pipework) will remain little changed.

Regards again

many danke