Stage 2 tune: My SCR, DPF, EGR and Urea delete Journey

[Stockx5]

^^^ what an eye opener to hear what a new turbo costs!

the hybrid turbo set up isnt' that much more money....

[seattle]

Hybrid turbos require messing with (taxing) electrical system - there's no free energy. That's something you'd want to avoid on a Bimmer especially.

Got an update from the shop:
* Small turbo will have regular maintenance - wasn't in bad shape, but disassembly (something I asked for, to inspect) automatically means new piston rings, etc. Should be $550 for rebuilt and cleaned with 1 year warranty.

* Large turbo is waiting for turbine wheel that shows damaged on that photo. Initial estimation was 10 weeks but local shop was able to convince corporate to pull some strings and new wheel will be here from Germany in about a week. Looking at about $800 out of the door there. Warrantied.

[seattle]

I've been researching and analyzing cases of oil seeping through compressor-side piston seal. There are a few scenarios that don't include any damage to turbo itself:
1. Restrictive (for any reason) air filter causes excessive vacuum in front of compressor, and sucks oil out. The piston rings are meant to hold air pressure from outside from reaching inside of turbo housing, but are less effective the other way. They say.
2. Excessive crankcase pressure (for any reason, such as clogged PCV) does now allow free-flowing oil return to get back into the sump via return hose. That results in oil pressure inside turbine housing and easiest way out is piston rings (e.g. turbo seals).
3. Clogged/bent oil return lines, same effect as #2.
4. Excessive DPF backpressure due to it clogged, and potentially overcomes the seal

Now, in my case, we confirmed that the only issue with the turbo is damaged turbine wheel resulting in space between piston ring, potentially/likely allowing exhaust gasses into turbine housing.

Setting aside reasons for damage for now, the following is likely/possible with that damage:
A. Exhaust gas pressure leaked into turbine housing, from there, via oil return line, into crank case, increasing crankcase pressure. See #2 above.
B. Exhaust gas enters from turbine side and pushes oil to the side, while oil is pushed by pump from the top. That is enough to overcome the "oil slingers" (the round grooves). After that, piston rings are not able to hold oil even at negligent pressure and oil ends up getting past the ring, and from there into clean air side of the turbo.

Now, how did the compressor wheel end up getting worn/damaged on turbine side?
I can only suspect compressor surge (turbo flatter for brits). Compressor surge results in violent shaking of compressor wheel and shaft, radial, but nothing prevents axial movement, which would transfer along the shaft to turbine wheel.

The wear mark on the photo looks as if the turbine wheel was pressed against turbo housing and rotated, causing the sharp edges to spike up. It may very well be possible that radial or axial movement of the shaft was enough to pin the wheel against housing and cause that wear/damage.

Just thinking.

Once everything is assembled in a couple weeks, I will certainly go perform crankcase pressure test as first thing.

[garagelogician]

You mention crankcase pressure. Have you considered valve cover gaskets? Apparently it is a problem that has been cropping up.

[seattle]

I have seen VCG mentioned as an issue for 35i and 50i but not 35d.
Not seeing any leaks in that area in my engine.
Either way, a leaky valve cover gasket may be result of excessive pressure, not cause of it, if I understand correctly.
If my vehicle has any excessive crankcase pressure, it appears to manifest itself in other areas.

[Stockx5]

Originally Posted by seattle

Hybrid turbos require messing with (taxing) electrical system - there's no free energy. That's something you'd want to avoid on a Bimmer especially.

the turbos I mean are the ones that are basically stock turbos with larger internals.


BMW 335D and X5 35D - Hybrid Turbo Kit - JR AutoTuning Performance

they are 2800 bucks. just something to think about.

Originally Posted by seattle

Once everything is assembled in a couple weeks, I will certainly go perform crankcase pressure test as first thing.

maybe a vented catch can is cheap insurance against this case scenario?

and would a smoke machine up the tailpipe throw smoke into your crankcase if it's true the oil return line is leaking gases into the crankcase?.

[garagelogician]

If you haven't already, check out the North American BMW Diesel Owners Group on FB. https://www.facebook.com/groups/NABDOG/

[seattle]

Originally Posted by garagelogician

If you haven't already, check out the North American BMW Diesel Owners Group on FB. https://www.facebook.com/groups/NABDOG/

"the Dmitry" recommended it a couple weeks ago when I stopped by his shop.
Joined.

[seattle]

Originally Posted by Stockx5

the turbos I mean are the ones that are basically stock turbos with larger internals.
BMW 335D and X5 35D - Hybrid Turbo Kit - JR AutoTuning Performance

they are 2800 bucks. just something to think about.

yeah, but ...

Other Requirements:
Stage 4 tune
Upgraded HPFP
Stepped intercooler

...a rabbit hole

Originally Posted by Stockx5

maybe a vented catch can is cheap insurance against this case scenario?

I do have ProVent 200 installed, with a couple extra holes drilled in addition to its incorporated pressure release valve.
One time in summer, observed some oil leaked down from under ProVent cover - must have hit pressure spike and released pressure from the valve, as designed. Been clean since then.

Originally Posted by Stockx5

and would a smoke machine up the tailpipe throw smoke into your crankcase if it's true the oil return line is leaking gases into the crankcase?.

Assuming the smoke will have enough pressure to reach all the way past any seals, the turbo will have its seal rebuilt by then.

[Stockx5]

^^^

yea I guess it's a lot more than you are spending.

----
going back to my cabin fumes issue I found the intercooler to turbo pipes have burn marks around the seal and oil seeping out as well as smoke burn out marks.



So i thought those lines run clean air but maybe not maybe the air circulating trough there is smokey air.

So it does not make any sense to start removing turbos if there are seals that are leaking in the intercooler.

But im still going to run the smoke machine first before replacing anything.

the inter cooler to intake pipe seal is worn as well all tho there is no smell from that area. I was able to fix it with some teflon tape lol I wonder if it burned off already it did make things super snug.