CAVE engine sudden increase in oil consumption but has perfect compression?

[FlexibleMouse]

Hi Guys

 

My engine suddenly started consuming lots of oil last week. My first thought was a piston failure so I bought a compression testing kit to verify. Just done the test and the compression is bang on (145-147) psi on all cylinders. However spark plugs 1-3 are all caked in oil (and the piston crowns look wet) but cylinder 4 has a perfect looking plug and a dry piston crown. My second suspect is a bad PCV but I would have thought all cylinders should be equally as oily on that case. Could be valve stem seals but I don't see 3 going bad all at the same time, anyone have any ideas?

[FlexibleMouse]

Update: 

 

I suspect the PCV has become gunged up and is not evacuating enough blow by when on boost. In theory this will be pressurising the crankcase pushing oil past the turbo oil seals. I'm thinking cylinder 4 is clean because it is furthest from the throttle body. 

 

First experiment, I have deleted the one way valve on the breather inlet. In theory this will work the same way on idle but provide a second route for blow by gas to vent on boost. 

 

Currently looking for a replacement PCV valve, also want to try a breather filter vented to atmosphere with the other pipes blocked to see what effect it has on consumption.

 

I will update in a few days with any changes, last oil consumption check was 0.93L/1000km.

[GT0161]

I. Actually watched a video online and in the video he states if your cars burning oil swap out the pcv  unfortunatly  i have no idea wht that is lol keep us updated this is interesting 

Edited 4 June, 2019 by GT0161

[Kobayashi]

Do you have the breather pipe mod, 1 of the early fixes? 

[GT0161]

Mine does not have that breather mod @Kobayashi

Edited 4 June, 2019 by GT0161

[FlexibleMouse]

No breather mod, from the photos I have seen of it they seem to have a slightly different layout to mine maybe they are CTHE engines?. I now have the boost solenoid venting to atmosphere to reduce throughput between the PCV and intake when on boost. Also I have a larger pipe coming tomorrow for the breather to see if that helps. I will check the oil again on Saturday to see if anything has helped or if I am barking up the wrong tree.

[GT0161]

Keep us posted 

[FlexibleMouse]

So far no progress, still using oil at the same rate. So I have ruled out the PCV system pressurising the oil return line problem as the cause. I'm putting it back to stock configuration while I figure out what to do next. 

 

Possible avenues to explore:

 

1. Oil seperator doing lousy job and PCV just throwing loads of oily vapour through.

 

2. Valve stem seals leaking on 3 cylinders.

 

3. Damaged oil control rings, but good compression rings.

 

 

[GT0161]

@FlexibleMouse hi mate maybe have a look into the oil squirter jets. It is beleived that they are one of the cause of high oil consumption due to the angle of the oil squirters. Aparently scirocco ones CAVd are the correct replacement ? Have a search on here. 

[Ootohere]

Seeing as they stopped fitting CAVE engines near 7 years ago i would forget fitting the new 'Oil Squirters' and find out what is wrong with the engine / head now.

[FlexibleMouse]

I have now ruled out valve stem seals, and I'm actually pretty sure it's all down to the breather / pcv. I was sure my engine was toasted but I have had no loss of performance (except the fact that  I put the car back to standard until I resolve the issue). 

 

Next week I am going to try a restrictor on the bigger pipe that goes to the intake, theory being that the crankcase is actually breathing too much, like a regular pcv valve stuck open.

 

Can someone who has had the "breather mod" fitted by a dealer post some pictures please? so I can see what they altered? thanks.

Edited 21 June, 2019 by FlexibleMouse

[GT0161]

@FlexibleMouse it is probably the oil squirter jets you want the scirocco squirters

[Kobayashi]

[Kobayashi]

Official Skoda garages won't do the fixes unless you do the 'oil consumption test'. the breather pipe is in that earlier photo, this was my bill I was out of warranty but you can see part numbers

Edited 23 June, 2019 by Kobayashi

[FlexibleMouse]

Thanks for the info, I wanted to see what they actually changed or re-routed because I have not seen any clear pictures of the fix. I will just do the fix myself once I can see how they changed the configuration. 

 

Currently at 1L per 1000km and now using a pcv restrictor for a couple of weeks to see if that does anything.

[GT0161]

Mines burning 0.9ltr to 500km 

[Kobayashi]

2 hours ago, FlexibleMouse said:

Thanks for the info, I wanted to see what they actually changed or re-routed because I have not seen any clear pictures of the fix. I will just do the fix myself once I can see how they changed the configuration. 

 

Currently at 1L per 1000km and now using a pcv restrictor for a couple of weeks to see if that does anything.

I saw the TPI's which were diagram work instructions of 'what to do' at the dealership when i was talking to the Master Technician (colne branch), They let me look at them, so they exist as full work instructions, someone should be able to get them for you. 

[FlexibleMouse]

1 hour ago, GT0161 said:

Mines burning 0.9ltr to 500km 

 

Maybe we could combine our resources and purchase an oil tanker to follow us round! 

[GT0161]

I think it will work out cheaper if we just go halfs on a flatbed and drive around with the skoda on the back lmao 

[thomasaspin]

has no one ruled out the turbo oil seals here? 

[FlexibleMouse]

Not completely, but I can tell you that my PCV system is full of oil before the turbo so that's where I am looking into right now. 

 

[Kobayashi]

Weird how  yours 'developed' into an oil burner, mine was like that from the start & that was back in 2012

Edited 23 June, 2019 by Kobayashi

[GT0161]

Dont know if this helps but on my first oil consumption test they said they suspect i toppsed it up with oil? Which is not the case at all. I wonder if the oil is hiding somewhere within the engine? 

 

I can 100% say i did not top it up and just before i took it back to skoda for the second part of the test the oil level was at least half way or just below half way on the dipstick! 

Edited 23 June, 2019 by GT0161

[FlexibleMouse]

4 minutes ago, Kobayashi said:

Weird how  yours 'developed' into an oil burner, mine was like that from the start & that was back in 2012

 

It has always burned oil but it wasn't enough to concern me, the previous owner has posted here about oil issues when he had the car too. I went from 5w40 to 5w40 and things improved slightly. I started to really pay attention to the usage and as of last summer it was about 0.7L/1000km. Then all of a sudden it jumped to around 1.0L/1000km a few weeks ago. I can accept 0.7L/1000km because it's done 67k and doesn't get the easiest life but 1.0L/1000km is taking the p***. 

[FlexibleMouse]

9 minutes ago, GT0161 said:

Dont know if this helps but on my first oil consumption test they said they suspect i topped it up with oil? Which is not the case at all. I wonder if the oil is hiding somewhere within the engine? 

 

I can 100% say i did not top it up and just before i took it back to skoda for the secind part of the test the oil level was at least half way or just below half way on the dipstick! 

 

I think they just screwed up the test because oil doesn't weigh the same water. I monitor my usage by volume with a measuring jug which is much simpler, I don't know why they complicate the matter by using weight.