Hi

 

We have a 2011 1.2 with CGP engine. I think the breather could be blocked - is this a common problem? 

 

Starting from cold, the idle is really rough and the oil light comes on, despite the oil level being fine. If I take off the filler cap the revs come back up but the light doesn't go off.

 

I've been trying to find a location for the breather but no luck so far. Is there a component locator picture for these engines, anywhere?

 

Thanks, A

 

 

Try

https://volkswagen.7zap.com/en/rdw/polo+derby+vento-ind/po/2011-672/1/103-103037/

 

20 and 22 are vent hose (pasted as upside down mirror image, but good on 7zap)

 

Thanks... now I'm really confused! 😄

https://volkswagen.7zap.com/en/rdw/polo+derby+vento-ind/po/2011-672/1/103-103005/

 

Actually this pic I think. 🙂 Item 30 or 9? I'll give them both a clean plus drop the oil and filter.

 

Many thanks, I didn't know about that site.

@dvderlm's diagram shows hoses that allow air into the rocker cover; the one you have identified from the PCV valve is the breather hose that recycles the crankcase fumes back into the inlet. 

 

Worth checking that you can blow air into the rocker cover through that #22/23 hose. It has a pretty small ID at the rocker cover I think, so don't expect much flow, but it shouldn't be blocked.

 

I may just have a spare oil separator if the part number hasn't changed, I replaced one with genuine new on an engine that shortly afterwards died of other causes.

 

Edit: another thing or two.

What colour is the oil warning light you're seeing, red for low pressure or yellow for low level? 

 

And try this: with engine running, find the small pressure equalisation orifice on the top cover of the PCV valve. With a little fingertip, feel whether air is being sucked in there by blocking it. If there does appear to be suction there, the valve diaphragm is ruptured or leaking.

The top cover comes off with careful releasing of a few plastic clips simultaneously,  Allowing visual inspection.

Edited 4 April, 20233 yr by Pete1

13 hours ago, Pete1 said:

@dvderlm's diagram shows hoses that allow air into the rocker cover; the one you have identified from the PCV valve is the breather hose that recycles the crankcase fumes back into the inlet. 

 

Worth checking that you can blow air into the rocker cover through that #22/23 hose. It has a pretty small ID at the rocker cover I think, so don't expect much flow, but it shouldn't be blocked.

 

I may just have a spare oil separator if the part number hasn't changed, I replaced one with genuine new on an engine that shortly afterwards died of other causes.

 

Edit: another thing or two.

What colour is the oil warning light you're seeing, red for low pressure or yellow for low level? 

 

And try this: with engine running, find the small pressure equalisation orifice on the top cover of the PCV valve. With a little fingertip, feel whether air is being sucked in there by blocking it. If there does appear to be suction there, the valve diaphragm is ruptured or leaking.

The top cover comes off with careful releasing of a few plastic clips simultaneously,  Allowing visual inspection.

 

Thank you! I will have a look. I'm going to change the oil and filter today.

 

It's just the yellow oil light for level; I did think it might be the oil level sensor but the tickover speed is definitely affected by taking the oil filler cap off... would a cold engine do this anyway, though? 🤔

 

*actually the pic he posted is not for my engine - I think that's the FSI. I assume the equivalent bit on my engine is #30 in the link I posted.

Edited 4 April, 20233 yr by 3narf
additional info

I'd expect a significant change in running from removing oil filler cap, but usually from running well to running worse.

4 minutes ago, Pete1 said:

I'd expect a significant change in running from removing oil filler cap, but usually from running well to running worse.

 

Hmm.. It speeds up with the cap off, then almost stalls when you replace it, but then recovers to a slightly slower idle.

Not getting enough clean air at idle, or too much recycled crankcase gas through pcv valve problem. Check diaphragm.

 

Air filter last replaced when?

1 hour ago, Pete1 said:

 

 

Air filter last replaced when?

 

😳 Not since we bought it a couple of years ago

I assume the PCV valve on my engine is the assembly at #30?

14 minutes ago, 3narf said:

 

😳 Not since we bought it a couple of years ago

There's your first port of call then, take a vacuum cleaner to the dirty side if fouled.

15 minutes ago, 3narf said:

I assume the PCV valve on my engine is the assembly at #30?

Yep.

OK, oil & filter changed and everything cleaned. Light is off now but I think I'll suspect an intermittent sensor if it comes back. Thanks for the help! Much appreciated.

 

*I can't believe the design of the oil filler. 😠 It's only got one purpose - to allow you to put oil in the engine. It seems like it's been designed to stop you getting any oil in there.

I know what you mean about the oil filler. 😁

 

 

On 04/04/2023 at 09:35, 3narf said:

*actually the pic he posted is not for my engine - I think that's the FSI. I assume the equivalent bit on my engine is #30 in the link I posted.

Here's the correct pic and part numbers for the fresh air hose stuff on your engine:

 

This image from an SSP document about the first generation of the 3-pot engines may help to understand the breather arrangement:

 

Thanks for all your help! Car running fine, no issues, MoT passed (after I replaced a front shock).