Main oil leak seems to be fixed since the alternator/oil filter bracket gasket was done, but there's still some coming out the back of the engine.

I think this may be the oil separator, or something higher up. Whole engine is pretty oily. ☹️

When I unscrew the oil filler cap with engine idling, it does a bit of a dance, which I think indicates that the PCV system isn't working at all brilliantly.

Researching this a bit via an Audi SSP on the CBZA/CBZB gave this page as the basic description of the system:

Having bought a genuine replacement oil separator, those 'Polyswirl' tubes are pretty tiny, and look to be easily blocked completely, leading to worse separation and possibly higher pressure upstream of them. You can't see through them at all, ID is maybe 3 or 4mm each; I think there's probably a spiral bit of plastic inside each, along their length, like a bit of fusilli pasta.

Plan is to replace this separator soonish. Looks like a bit of a pain, due to position on rear of block, just above O/S driveshaft which will have to be moved aside, if not completely removed. It also has a sealant gasket arrangement, which I'm not that fond of dealing with. Sealant on order due soon.

Some pics of the (new) oil separator and the detachable 'business section'.

Sealant arrived today, and car isn't needed tomorrow, so I must have a go starting reasonably early in the morning.

🤞

If anyone reading has changed one of these on a CBZA/CBZB engine, and has any tips, I'd be happy to hear them.

Got the old one off, with predicted struggle.

Secondary water pump shifted off it and tied up out of the way, then driveshaft off and out of the way.

Wouldn't really be do-able without driveshaft shifting, and would be another step easier with front exhaust/cat section off but that's a mission of its own, so haven't done that.

Pretty grubby, as expected.

Finally defeated the ECU anti-tamper bracket yesterday afternoon, so that I could get in and check continuity/shorts for the oxygen sensor wiring. Since almost day one of our ownership, stubborn lambda sensor faults pop up putting on the emissions light. Both sensors replaced with good quality items, and no wiring issues discovered yesterday.

Hoping it turns out to be injector related, as claimed by the garage the previous owner used. I'm not sure how they came to that conclusion, but they claimed a couple of injectors were leaking, apparently.

I've (cheaply) acquired a set from a much lower mileage 1.2 TSI, and had them cleaned and tested by a localish outfit that I trust. Should be swapping those in next week I hope.

Edited 6 June, 20256 Jun by Breezy_Pete

Big day planned for tomorrow.

Refurbed injectors and a much lower-mileage high-pressure fuel pump getting swapped in, I hope.

Also the cam follower for the HPFP, unless the original looks much better than expected for nigh-on 160k miles.

The company that cleaned and tested the replacement injectors very helpfully also changed the PTFE seals and the o-rings at the top, so should be reasonably idiot-proof to fit. 🙂

Anyone swapped out these items?

HPFP has to come off to get injector rail out, so looked into that too, and picked up a far lower mileage one from ebay, for not a lot of money. Apparently the cam follower can get worn to the point of perforating, so I picked up a Febi one of those for not much over £20 via amazon.

Edited 10 June, 202510 Jun by Breezy_Pete

Injector and HPFP replacement appears to have made no obvious difference to anything, disappointingly. But having refreshed bits in those places can only be good in the long-term.

Had a bit of a breakthrough an hour or so ago though, whilst cleaning up and studying an inlet manifold with intercooler that I'd acquired very cheaply from a much lower mileage car.

The PCV (positive crankcase ventilation) system relies on a subtle feature of this manifold, which appears to be a bit of design frailty, at least for pressure reduction at low throttle openings.

When I first looked at the relevant "fifth port" on the spare manifold, it was very easy to conclude that it had a plastic blanking plug in it. Perhaps because the design had ben changed to apply a bit of vacuum to the crankcase in some other way.

Didn't photograph it before my breakthrough, sadly, but after leaving it for a few hours and going back to it and having more of a (literal) poke around, I found a teeny-tiny hole that is fundamental to the design.

The tiny hole you can see in the first pic, especially after seeing it in the closer shot, was utterly occluded and invisible at first.

Edited 21 June, 202521 Jun by Breezy_Pete

Hi Pete,
Best of luck with project.
That motor is very fortunate to have ended up with you.

I have just done a cv boot on mine... wish I had seen your CV boot shaft removal tool trick before hand!

14 hours ago, Breezy_Pete said:

The tiny hole you can see in the first pic, especially after seeing it in the closer shot, was utterly occluded and invisible at first.

Perhaps you should change your moniker to "Heiniken_Pete" - reaches the parts other mechanics do not reach :)

I didn't find time (or energy) yesterday to fit that replacement, refurbed manifold. Wednesday should give me the opportunity.

Can't wait to see if it resolves the crankcase breathing issue (see vid above of oil filler cap dancing). Confirmed there was a problem by looking for a little 'suck' on the air inlet pipe* to the cam carrier/valve cover and finding not a hint of flow into the system. I'm quite confident that the manifold is going to be very wet with oil that hasn't separated properly, and that the little jet/hole seen in Saturday's post is going to be equally occluded. The spare manifold was from a car with around 1/3 or even 1/4 of the mileage that ours has. At idle, inlet manifold vacuum should be ported/jetted through that tiny hole found on Saturday, above.

*That little air pipe has been made infamous by people breaking off the non-return valve at the engine end of it whilst changing the air filter, see here for example.

From another SSP with slightly clearer diagrams and annotations than the Audi one, bottom right exploded view shows the 'suck' that ought to be happening at/near idle.

Edited 23 June, 202523 Jun by Breezy_Pete

That tiny hole was indeed blocked on the manifold in the car, and fitting the spare manifold with it all cleaned out has rectified the 'dancing oil filler cap' problem.

Didn't make any difference to the ever-present oxygen sensor faults though. I was pretty despondent about that; tried so many blind alleys trying to sort that.

However....

Just had a breakthrough, finally.

I was making some test leads from the cables of the original oxygen/lambda sensors, to enable easier double-checking and load testing of the loom wiring between sensor connectors and ECU.

One in particular was very oily all over the outside of the wires, and after cutting and stripping with the intention of fitting some 4mm sockets to each wire, it was apparent that the copper within the insulation was also oily.

I faintly remember reading once upon a long time ago that a reference level of oxygen is ported into the sensor down the gaps between conductor strands, sounds mad doesn't it?

Anyway, that got me googling 'oil contamination of oxygen sensor connectors', and that got me to here:

https://www.ngkpartfinder.co.uk/assets/Uploads/Sensor-oil-contamination-ver2.pdf

Doesn't mention oxygen movements but does clearly indicate that an oily set of connector contacts can be problematic.

Luckily, I had a spare 6-way connector of the right flavour for the precat sensor, with a few inches of wire hanging out. Cut and shut that into the engine bay loom and hey presto, bugger me gently with a chainsaw, sensor 1 code gone and not returning.

I was close to seeking professional help on this, for the car and my mental state. 🙂

Just need to find a 4-way connector for the post-cat sensor now.

🥳

Sensor 2 still playing up even with a new loom connector and carefully cleaned sensor connector.

That sensor has been on there for a couple of months though, so oil may have got too far up it. Cheapish aftermarket replacement due midweek.

Just found this on YT:

How Oil Destroys Lambda Sensors & How to Fix It

New post-cat sensor was delivered yesterday, and fitted just now.

For the first time since purchase, this car is showing no fault codes in the engine ECU.

😁🥳

A milestone! Well done Pete (and ECU)

The gift that keeps on giving...

Was under it this afternoon changing the oil, not expecting to see this:

Nearside outer CV boot decided to let go, thoroughly.

What a right PITA. I take it you'll change both, Pete?

29 minutes ago, Lee01 said:

What a right PITA. I take it you'll change both, Pete?

Not sure if you mean both boots on that driveshaft or both outer boots? If the latter, offside one was one of the first jobs when it arrived here.

Plan is to swap in a whole nearside driveshaft. Ordered one from ASM from a Roomy with only 55k on the clock for a very good price.

May have to collect it on Monday to expedite things.

1 hour ago, Breezy_Pete said:

Nearside outer CV boot decided to let go, thoroughly.

And with some aplomb 🙄

With the use of my yuckygreaseometer and aspectratioviscometer, and using AI to measure the runs on your sidewall, it looks like it let go at 37.832mph. Time of death 0912am, 17 July 2025 😁

Gaz

Big ole split

Fingers crossed please friends.

Dropped off the Rescue Roomster at a garage round the corner just now.

MOT not due until December 24th (how did that come about?), but wanted to bring it forward to a more conducive time for working on cars.

Replaced the flexi on the exhaust yesterday, and changed one slightly whitish indicator bulb, but other than those, didn't spot any obvious fails.

We shall see.

There's a small pit/crack in the front windscreen, but near the middle, below the rear view mirror, so I think it'll be OK. Don't think it has been an advisory previously.

All the best, Pete 🤞

Thanks Lee, much appreciated.

18 minutes ago, Breezy_Pete said:

small pit/crack in the front windscreen

Our insurers will arrange to have those filled FOC as long as they are 'minor' and don't impinge on the driver's eyelines. I'm assuming such a service is generally available - but I haven't asked.

P.S. It's getting difficult to cross my fingers for long these days so will crossed eyes do it for you? :)

Close but no cigar, as they say.

Both headlights aim too low and too far to the right; which is a bit odd.

They'll adjust those prior to retest.

OSR wheel bearing rough.

Bought a spare for the wheel bearing a while back, but was in one of those quandries "is the noise definitely coming from the right?" Neither of us could tell for sure from sitting in the back seat while being driven.

Wish I'd done a bit more investigation, with hindsight.

Will get into that this afternoon, in the first rain for ages...😆

Could have been a lot worse, I think.

Yeah, sounds like you got off pretty well but considering the amount of work you've had to put in that's not a bad outcome at all really.
Viel Glück for the retest, Pete