Poorly done PCV replacement causing issues?

[Morritse]

Had my PCV replaced a few thousand miles ago due to extensive coolant loss.

The coolant loss was fixed, however I noticed that since the replacement. I have very slow but consistent oil and coolant loss. I also noticed that the pressure in the coolant loop seems higher than normal; when I take off the fill cap, the coolant level shoots up as much as 2 inches.

I have a knack that this increased pressure cracked one of my intercoolers, leading to coolant loss and misfires in cylinder 3.

Any idea what could have gone wrong? And why I'd be burning oil as well? (Have to add a quart every ~1.5-2k miles.

[Morritse]

This is what I'm referring to

https://youtu.be/5BT7dYZbWq8

[GandalfTheIbis]

I must question what could be poorly done about the PCV replacement? I believe mine is still on my car from factory and I experience oil loss at a similar rate to what you described. I was planning on changing my PCV as a result of the oil loss. I've never experienced notable coolant loss that was not immediately following a service.

[ntsantos]

I had a minor coolant loss in the A7, and it ended up being a damaged SC intercooler. I was getting misfires in Cyl 5 consistently on WOT pulls. I think I dinged it when I installed a ported blower the first time. I was lucky I kept my stock one in tact, I was up and running in an hour. If you pull the blower you'll know immediately by looking down the ports.

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[S4'ed]

The PCV unit cannot alter the pressure in the cooling system. The coolant just flows thru a passage in the plastic body of the PCV unit, to heat the PCV (prevents moisture freeze-up of the crankcase vapor passages of the PCV).
And many 3.0 V6's suffer from a very slow loss of coolant...even with none of the typical leaks (intercoolers, water pumps, PCV, thermostat).

There is really nothing that can be poorly done during the install of the PCV, either it doesn't leak coolant and/or blowby gases, or it does.

The coolant level increasing when you release the cap is normal...it is just all the rubber hoses collapsing a little as the normal hot operating pressure is released.

Maybe your oil consumption is related to the ECU change/update that Audi specifies if the PCV unit is updated to the later revision, due to the slightly different crankcase vacuum level that the new PCV units regulate. I don't really think that the ECU update has anything to do with your oil consumption, I think Audi just updates the ECU so that it doesn't set an emissions DTC due to the different amount of PCV airflow that is pulled into the intake (this is unmetered air).

[Morritse]

The PCV unit cannot alter the pressure in the cooling system. The coolant just flows thru a passage in the plastic body of the PCV unit, to heat the PCV (prevents moisture freeze-up of the crankcase vapor passages of the PCV).
And many 3.0 V6's suffer from a very slow loss of coolant...even with none of the typical leaks (intercoolers, water pumps, PCV, thermostat).

There is really nothing that can be poorly done during the install of the PCV, either it doesn't leak coolant and/or blowby gases, or it does.

The coolant level increasing when you release the cap is normal...it is just all the rubber hoses collapsing a little as the normal hot operating pressure is released.

Maybe your oil consumption is related to the ECU change/update that Audi specifies if the PCV unit is updated to the later revision, due to the slightly different crankcase vacuum level that the new PCV units regulate. I don't really think that the ECU update has anything to do with your oil consumption, I think Audi just updates the ECU so that it doesn't set an emissions DTC due to the different amount of PCV airflow that is pulled into the intake (this is unmetered air).

Ok. Makes sense. As far as oil consumption goes it only started happening after I had the PCV replaced.

[Dr GP]

Did you happen to replace the older PCV version with the updated one? They are different and interchangeable. If so , settings need to be changed to lower pressure. Sorry to be vague but I do not have the specifics.I had my 2011 PCV valve replaced but used the same type of PCV valve. Perhaps there is residual air trapped in the coolant system and bleeding out?

[ValidatedS4]

newest version for 2013+ is: 06E103547AB
newest version for >2012 is: 06E103547AC

https://www.ecstuning.com/Audi-B8_S4...Oil_Separator/

I think there could be a lot that can go wrong during a replacement of anything...

Did you replace the coolant pipe everyone else recommends replacing?

Maybe O-rings or other damage to coolant pipes while doing the replacement?

Or the last possibility is if you didn't replaced the water pump/thermostat when you did the PVC; those could be leaking.

I'm thinking if doing my PVC as well as I have a little coolant/oil loss. Not terrible. But in my case I think my valve cover/oil pan/other seal is leaking and maybe there's a leak somewhere else in the coolant loop as well.

Short story is that there is a lot of possibilities to why your having both loss of coolant/oil. I'd check all to start narrowing down.

[Morritse]

newest version for 2013+ is: 06E103547AB
newest version for >2012 is: 06E103547AC

https://www.ecstuning.com/Audi-B8_S4...Oil_Separator/

I think there could be a lot that can go wrong during a replacement of anything...

Did you replace the coolant pipe everyone else recommends replacing?

Maybe O-rings or other damage to coolant pipes while doing the replacement?

Or the last possibility is if you didn't replaced the water pump/thermostat when you did the PVC; those could be leaking.

I'm thinking if doing my PVC as well as I have a little coolant/oil loss. Not terrible. But in my case I think my valve cover/oil pan/other seal is leaking and maybe there's a leak somewhere else in the coolant loop as well.

Short story is that there is a lot of possibilities to why your having both loss of coolant/oil. I'd check all to start narrowing down.

I'm 90% sure my intercoolers is leaking. One of them. Don't understand why I started burning oil though, unless it's because of the specific oil the shop used when changing PCV (they did an oil change afterwards)

[ModItNow]

I'm 90% sure my intercoolers is leaking. One of them. Don't understand why I started burning oil though, unless it's because of the specific oil the shop used when changing PCV (they did an oil change afterwards)

Not sure if it's the oil your shop used but I recently used oem equivalent Castrol and I burned some before my next oil change. I usually never burn oil, using Motul this time around

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[Dr GP]

Usually replacing a bad PCV valve rectifies an oil consumption issue. Is it possible the new PCV valve is faulty since replacing it seems to have caused oil consumption. Perhaps the PCV valve was not the cause of you initial coolant loss ? Old PCV valve= no oil consumption .New PCV valve=oil consumption. If nothing else was changed and everything put back correctly and not damaged, logic would indicate there is something wrong the the new PCV valve? Yes?No?

[Morritse]

Usually replacing a bad PCV valve rectifies an oil consumption issue. Is it possible the new PCV valve is faulty since replacing it seems to have caused oil consumption. Perhaps the PCV valve was not the cause of you initial coolant loss ? Old PCV valve= no oil consumption .New PCV valve=oil consumption. If nothing else was changed and everything put back correctly and not damaged, logic would indicate there is something wrong the the new PCV valve? Yes?No?

Right, I was right about the coolant leak, I think. I changed an intercooler yesterday and it was definitely leaking into Cyl 3.

I have noticed that oil consumption has slowed down, but it's still there, I'll give it some time.