In the last few months I have had a couple of instances where the car is incapable of exceeding ~55mph, even though the engine revs just fine. I also found that there was no turbo whistle, so it seemed that boost was not being built. It was intermittent, but the car's drivability had become rather poor, with uneven power delivery and shifting. All of this, combined with reading online, pointed to either a bad turbo, or more likely, a problem with the VNT actuation. A friend has a VCDS tool that I can borrow, but I did not even bother with it since the issue seemed fairly clear.
Given that turbo removal is a bit of a pain in the rear, and it has ~250,000 miles on it, I just went ahead and ordered a new one. The entire thing is about 2X the cost of just the VNT actuator at IDParts, and I decided to refresh the whole thing and not have to worry about it anymore. TLDR, the vacuum diaphragm in the actuator was broken and unable to hold vacuum. The VNT linkage was a little gummy and had some resistance, but overall it was nothing that a properly working actuator would have had an issue with.
Anyway, with some background laid out, I'll get into the repair project here. I am more or less at the 50% completion point right now since I am waiting for the camshaft replacement kit to be delivered. Everything is fully disassembled and (mostly) cleaned up, so reassembly is all that is left to do.
Starting from the top, I started pulling stuff off of the engine.
This was about as far apart as I could easily get it from the top side. I removed the ASV and EGR valve as well after taking this picture since those are easy to do from the top. In hindsight, having later unbolted the rest from under the car, I could probably get at all of it from the top.
Yuck! There would be some cleaning to do...
I highly recommend labeling the vacuum lines that you unplug since there are several of them, and it does not hurt to label the various electrical plugs.
I have had this car for a little over 5 years and 50K miles. The previous owner claimed to have done a LOT of work on it shortly before selling it...cam and lifters, cleaned out EGR system, DSG clutch and flywheel, and some other stuff. This seems like a plausible amount of gunk for 50K miles, especially on a higher mileage engine with a lot of original major equipment and a leaky vacuum actuator which will have the tandem pump blasting a lot more air through the PCV system.
Axle removal was easy since I replaced those shortly after buying the car. They both needed replacing again due to torn boots, so I was not too sad about having to remove them for this. The back of the engine was oily and gross. A lot of the nastiness seemed to be coming from leaks around the turbo and boost pipes / intake manifold.
The turbo was pretty easy to drop out of the bottom, and I did not even need to unbolt the EGR cooler. Getting the downpipe / catalytic converter out was actually more difficult. Knowing what I do now, the turbo would be easy to get out from the top side too. You could probably leave the axle in too. Just reach up and unbolt the turbo / exhaust manifold, drop it down a bit so it rests on the axle, unbolt the intake manifold and pull it out the top, and then lift the turbo out the top. You may or may not need to remove the valve cover...I intend to experiment with this when I reassemble things and will report back then.
At the start of this, I had only planned on replacing the turbo. Unfortunately, the fitting for the oil feed line seized onto the coupling nut and the threaded portion in the turbo cartridge was what came loose. I ordered a flexible stainless-braided line from Cascade German to replace this thing since getting a new OEM hard line in is a heck of a chore. Removal was easy with a hack saw. The new flexible line did require some minor modification to fit. I am not sure if this is the case for the manual and automatic transmission variants of the BRM, but in my case with the DSG the sheet metal baffle that goes between the block and transmission housing protrudes out a little and is in the way of the line as it comes off of the oil filter housing. I was able to trim off the overhang with a hack saw blade and file everything smooth, leaving just enough clearance to get the line and fitting in place.
Everything got a thorough cleaning. The intake manifold took 5 or 6 passes in the ultrasonic cleaner. At one point I used a lye-based degreaser to speed things up. Alkaline cleaners are a major no-no with aluminum since it will attack and dissolve the metal. At least in the case of the intake manifold, it is thick and there is nothing on it with a really critical tolerance, so I was fine with some minor etching since the degreaser demolished the sooty build-up in ~10 minutes.
The The rest of the nasty stuff was either disassembled (EGR valve) or carefully dipped and scrubbed (ASV). All of the fasteners got a badly needed cleaning too.
Ok, so things were going well, with the only unexpected change in scope being the oil feed line. Cool. Well, since it is trivially easy to get the valve cover off with the intake out of the way, I figured that I would get a peek under there since I had not looked at stuff since early 2020 after getting the car.
And with that, the project got much more involved lol.
The exhaust valves and lifters were very obviously on their way out. This certainly explained where all the fine ferrous crap on my magnetic oil drain plug was coming from over the last few oil changes.
I briefly waffled with the idea of leaving it alone and dealing with it sometime in the near future, but since things were already nice and disassembled, I did the smart thing and ordered the replacement items. Cam, lifters, bearings, and even a new tandem pump since the original one was still in there and my last few oil changes have returned exactly as much oil as I have put in despite some small leaks and the amount of PCV discharge. I do not know if it was leaking fuel into the upper head or not, but I was not intending to gamble on it.
So, I prepared for cam removal. I am used to a DOHC chain-driven engine in my 1991 BMW 318iS (or 321iS these days), and the SOHC belt-driven system in this car is pleasantly simple to deal with. I made some obvious visual indicators with a marker and pinned the camshaft at TDC with a 6mm drill bit.
Thereafter I removed the timing belt and turned the crankshaft back 90 degrees to ensure that valves would be safe from pistons as I worked on stuff up top.
Removal of the cam hub was easy with a generic harmonic balancer puller tool (can be found at local parts stores for $25-40). I used the long M8 fasteners from the injector pump rockers with some generic M8 washers to hold the puller, and later stuck a large screwdriver between two of the bolt shanks as a counter-hold tool (to break the 18mm bolt loose). I had to hold the 18mm bolt while applying the puller to prevent it from threading it back in lol.
Prior to tandem pump removal, I evacuated the diesel fuel from the head and T/P. One of these little hand pumps is so handy and I feel like it is an essential tool for anyone working on a diesel engine.
Given that turbo removal is a bit of a pain in the rear, and it has ~250,000 miles on it, I just went ahead and ordered a new one. The entire thing is about 2X the cost of just the VNT actuator at IDParts, and I decided to refresh the whole thing and not have to worry about it anymore. TLDR, the vacuum diaphragm in the actuator was broken and unable to hold vacuum. The VNT linkage was a little gummy and had some resistance, but overall it was nothing that a properly working actuator would have had an issue with.
Anyway, with some background laid out, I'll get into the repair project here. I am more or less at the 50% completion point right now since I am waiting for the camshaft replacement kit to be delivered. Everything is fully disassembled and (mostly) cleaned up, so reassembly is all that is left to do.
Starting from the top, I started pulling stuff off of the engine.

This was about as far apart as I could easily get it from the top side. I removed the ASV and EGR valve as well after taking this picture since those are easy to do from the top. In hindsight, having later unbolted the rest from under the car, I could probably get at all of it from the top.

Yuck! There would be some cleaning to do...

I highly recommend labeling the vacuum lines that you unplug since there are several of them, and it does not hurt to label the various electrical plugs.

I have had this car for a little over 5 years and 50K miles. The previous owner claimed to have done a LOT of work on it shortly before selling it...cam and lifters, cleaned out EGR system, DSG clutch and flywheel, and some other stuff. This seems like a plausible amount of gunk for 50K miles, especially on a higher mileage engine with a lot of original major equipment and a leaky vacuum actuator which will have the tandem pump blasting a lot more air through the PCV system.

Axle removal was easy since I replaced those shortly after buying the car. They both needed replacing again due to torn boots, so I was not too sad about having to remove them for this. The back of the engine was oily and gross. A lot of the nastiness seemed to be coming from leaks around the turbo and boost pipes / intake manifold.

The turbo was pretty easy to drop out of the bottom, and I did not even need to unbolt the EGR cooler. Getting the downpipe / catalytic converter out was actually more difficult. Knowing what I do now, the turbo would be easy to get out from the top side too. You could probably leave the axle in too. Just reach up and unbolt the turbo / exhaust manifold, drop it down a bit so it rests on the axle, unbolt the intake manifold and pull it out the top, and then lift the turbo out the top. You may or may not need to remove the valve cover...I intend to experiment with this when I reassemble things and will report back then.

At the start of this, I had only planned on replacing the turbo. Unfortunately, the fitting for the oil feed line seized onto the coupling nut and the threaded portion in the turbo cartridge was what came loose. I ordered a flexible stainless-braided line from Cascade German to replace this thing since getting a new OEM hard line in is a heck of a chore. Removal was easy with a hack saw. The new flexible line did require some minor modification to fit. I am not sure if this is the case for the manual and automatic transmission variants of the BRM, but in my case with the DSG the sheet metal baffle that goes between the block and transmission housing protrudes out a little and is in the way of the line as it comes off of the oil filter housing. I was able to trim off the overhang with a hack saw blade and file everything smooth, leaving just enough clearance to get the line and fitting in place.

Everything got a thorough cleaning. The intake manifold took 5 or 6 passes in the ultrasonic cleaner. At one point I used a lye-based degreaser to speed things up. Alkaline cleaners are a major no-no with aluminum since it will attack and dissolve the metal. At least in the case of the intake manifold, it is thick and there is nothing on it with a really critical tolerance, so I was fine with some minor etching since the degreaser demolished the sooty build-up in ~10 minutes.


The The rest of the nasty stuff was either disassembled (EGR valve) or carefully dipped and scrubbed (ASV). All of the fasteners got a badly needed cleaning too.


Ok, so things were going well, with the only unexpected change in scope being the oil feed line. Cool. Well, since it is trivially easy to get the valve cover off with the intake out of the way, I figured that I would get a peek under there since I had not looked at stuff since early 2020 after getting the car.
And with that, the project got much more involved lol.
The exhaust valves and lifters were very obviously on their way out. This certainly explained where all the fine ferrous crap on my magnetic oil drain plug was coming from over the last few oil changes.


I briefly waffled with the idea of leaving it alone and dealing with it sometime in the near future, but since things were already nice and disassembled, I did the smart thing and ordered the replacement items. Cam, lifters, bearings, and even a new tandem pump since the original one was still in there and my last few oil changes have returned exactly as much oil as I have put in despite some small leaks and the amount of PCV discharge. I do not know if it was leaking fuel into the upper head or not, but I was not intending to gamble on it.
So, I prepared for cam removal. I am used to a DOHC chain-driven engine in my 1991 BMW 318iS (or 321iS these days), and the SOHC belt-driven system in this car is pleasantly simple to deal with. I made some obvious visual indicators with a marker and pinned the camshaft at TDC with a 6mm drill bit.



Thereafter I removed the timing belt and turned the crankshaft back 90 degrees to ensure that valves would be safe from pistons as I worked on stuff up top.

Removal of the cam hub was easy with a generic harmonic balancer puller tool (can be found at local parts stores for $25-40). I used the long M8 fasteners from the injector pump rockers with some generic M8 washers to hold the puller, and later stuck a large screwdriver between two of the bolt shanks as a counter-hold tool (to break the 18mm bolt loose). I had to hold the 18mm bolt while applying the puller to prevent it from threading it back in lol.

Prior to tandem pump removal, I evacuated the diesel fuel from the head and T/P. One of these little hand pumps is so handy and I feel like it is an essential tool for anyone working on a diesel engine.
