Blue Smoke

[ttelracs]

Whilst driving on Sunday I came down a steep hill pulling up to a junction and noticed blue smoke wafting behind me.  I was in 2nd gear probably doing about 20mph coming to a halt with the wind from behind blowing smoke past me. As I queued it then stoppe, but when I pulled away and turned left at the junction it was like someone had fitted a blue smoke gun to the back of the car and the cars following me backed right off.  I fully expected the engine to stall, sputter and die with the death rattle or pistons meeting valves... but no, nothing.

I continued my journey of another 20 miles including motorway and A road without incident and drove back from my destination about another 30 miles with no issues at all.  Today I did another 70 miles with motorway and A road without issue too.  After giving it much thought I think this was a build up of oil in the boost pipes which got dislodged coming down the hill and sucked into the engine in one hit.  Any thoughts on my opinion as it doesn't seem to be drinking much oil.

[ROH ECHT]

That is the first signs of a rebuild in your future.
Mine started doing this seven years ago. Would make smoke when coasting in a low gear...then started smoking when rolling from a stop after making smoke when coasting. The smoke and oil usage kept getting worse and worse. Finally oil loss was at 1L/800 miles. I thought it may only be the valve stem seals and guides. So I planned to have the head rebuilt. Upon removing the head, there was a bunch of oil in the #3 and #4 combustion chambers. So those two pistons were removed and we discovered the rings were stuck in the piston grooves. The rings came out of the #3 piston but would not come out from the #4 piston. I replaced those two pistons, all of the rings and rod bearings. The head was rebuilt with new valve stem seals and guides, as the seals were hard and brittle and the guides were worn. You might consider removing all four plugs to see if any are coated in oil. If yours is anything like mine was...there will be oil on them or if any look different. But they may show no signs. Because as you can maybe see in my pic...the plugs aren't dark like the rest of the combustion chambers.

This was right after the head was removed from mine:

[ttelracs]

Thanks for the heads up.
If that's the case, I'll run it till it dies as I won't be spending any more money on it (he says).

Then in the next breath, maybe remove the head and get it checked, maybe rebuild it myself or buy a refurbed head. Maybe buy a spare now and rebuild that  then swap over.  I rebuilt an Audi 80 2.0L engine about 18 years ago, unsure I would want to do it all again. We'll see.  I have a turbo which had been checked over by r-tech in the garage so could do a build the head up and add the turbo... Argh, I'm doing man maths again.

[OllieVRS]

I wouldn't be jumping to conclusions just yet, I had blue smoke on deceleration because my turbo oil seals were leaking.

I got the turbo rebuilt with a new core, gave it a blast up and down the motorway to clear out the pipes/intercooler of oil, and the smoke hasn't come back since.

If you aren't already on 5W-40 oil I would switch to it, this should squeeze out a little more life out of your engine if it's on its last legs.

It's weird that it's smoking yet not consuming much oil, mine was drinking 5.0L/1000km before the turbo job, and 0.4L/1000km after (in combination with replacing the rocker cover gasket and vacuum pump seal).

What's the mileage? Has the oil been changed regularly?

[pudding]

I imagine you'd need a lot of high G cornering forces to draw that much oil out from the bottom of the intecooler/pipework up into the intake?

MK7 Rs did suffer with oil surge on track days dumping oil into the intake via the PCV though, so it can happen.

That behaviour is also very typical of valve guide/seal wear though, especially if coasting down a hill in a taller gear or in neutral reduces the smoke, so just keep an eye on it.

[ROH ECHT]

Yes, I did not add my symptoms prior to replacing the turbo for the symptoms the OP stated. But I did replace the K04 on mine in 2020. Its smoking then, occurred during full throttle and some at idle.

[ttelracs]

Thanks all for the replies.
I'll clean out the intercooler pipes and keep an eye on it.  I also have a refurb turbo which I could swap out as the worn seals do make sense hence the boost pipes filling with oil.  I think, turbo seals, valve guides, general wear on the rings maybe and it all adds up to oil loss.

[pudding]

I had very small amounts of blue smoke when the engine was hot and idling in traffic for ages, it would just puff out a cigarette exhale's worth when tapping the gas, and then be fine for the rest of the journey.

That all went with a new turbo.  The original one had worn thrust bearings, which is the most common cause of turbo seals failing to keep oil within the CHRA.

Seems to be a thing with modern DI turbo engines tbh.  I've followed much newer cars, like MK7s, 135is etc that smell oil burny and puff a bit in heavy traffic.