# Turbocharger rebuild (stock K03) with upgraded bearings



## Sandman333 (Oct 28, 2002)

I've decided to rebuild my turbocharger after the journal and thrust bearing failed at ~136,xxx+ miles. Almost all of that was APR Stage 1 93 octane tuned. I'm the original owner of the car. The car is a 2008 Passat 6MT w/ the 2.0T BPY engine. The turbo was vibrating excessively and making a loud hair dryer/horn sound (best description I can think of) even at idle, and was no longer making any boost.

As I disassembled the turbo, I found a bit more carnage than I was hoping for. I could feel about 1/8"+ of turbine shaft play along the thrust axis and there was also excessive lateral play. What I didn't know was that both the exhaust turbine and compressor had contacted their respective housings. 

The compressor wheel appears to have barely contacted the inside of the housing, with just one fin visibly bent, and only slightly. The turbine wheel didn't fare nearly as well, with a good chunk of the base completely missing and obvious contact on all the fins. See pics below.










I also noted that there were three cracks in the turbine housing/exhaust manifold under the waste gate valve. Apparently that is very common for these turbos. Unfortunately, there is no way to install any kind of hardened seat under the waste gate valve. The valve is permanently attached to the arm, which rides in a bushing that is permanently attached to another arm and pivot that attaches to the control rod. I suppose it would be possible to remove the valve from the housing and then get a machine shop to machine out the seat area and install something there equivalent of a hardened exhaust valve seat. I do have a source for a replacement waste gate valve and bushings. http://www.turbolabofamerica.com sells them now. As far as I know, these have not been available before and if the valve fell off the arm you had to replace the entire turbo as the one piece turbine housing/exhaust manifold wasn't available separately. I don't think I'm going to go to all that trouble with this build. The car is likely going to my youngest son when it's running again. This is also where I got the bearing/seal rebuild kit for $51.50. More on that below.

Incidentally, that brings me to my next bit of information. Thanks to a member here (thanks GTI's), I was able to source a brand new turbine housing/exhaust manifold. The company ships out of Lithuania. They do take PayPal, though I was not able to complete that at their web store. I wrote them an email about what I needed and they sent me a PayPal invoice. I also bought a new cartridge for this turbo from them. Both parts are listed as brand new. The entire turbo is actually available from them for less money (refurbished) than just these two new parts, but it's currently out of stock. $440 for both parts, including shipping. They did mention that I may have to pay US Custom & Import taxes. The parts should be here Friday (ordered early this morning, so 2-3 day ship time by DHL) and I do have tracking information. The parts are available here: https://turbocentras.com/parts-catalog/2971-turbocharger-5303-970-0105.html

The turbo rebuild kit, including a video describing the improved bearings included, is here: http://turbolabofamerica.com/ko3-ko4-turbo-rebuild-kit/. A video from this same guy showing how to assemble the turbo (not the exact same one, but the procedure is the same) is here: https://m.youtube.com/watch?v=H6EGe3hWTVM. Those were immensely helpful as I've never rebuilt a turbo before (have rebuilt engine, though).

See pictures from the turbo disassembly below.









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## Sandman333 (Oct 28, 2002)

More pictures from disassembly.









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## Sandman333 (Oct 28, 2002)

More disassembly pics.









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## Sandman333 (Oct 28, 2002)

These last three photos show a modification that I'm thinking about doing. If you watch the video on the product page at turbolabofamerica linked in the OP, you can see how much larger the oil feed holes are in their journal bearing vs the stock bearing pictured here:










That's great, but inspecting the inside of the turbine shaft bore shows that there is only one small feed hole from the turbo oil supply fitting to the journal bearing. This feed hole is a straight shot to the journal bearing area from the fitting opening:










The oil feed hole for the thrust bearing intersects the journal bearing feed hole at 90°. You can see the journal bearing feed hole down in the cartridge shaft bore, as well as the thrust bearing feed hole in this pic:










I'm not sure how the very large oil feed holes of the turbolabofamerica kit improve oiling of the shaft journal bearing when they can only be fed by this one small oil feed hole.

The modification I'm considering then becomes obvious: drill out both holes as large as possible without compromising the coolant passages. I would think that both holes would need to be drilled to matching diameters (or if they are currently different diameters, drilled so that they maintain the same diameter ratio) so that proper pressure and respective flow rates are achieved. This should help increase oil flow to the turbo bearings, a good thing. Obviously I could not drill those holes to anywhere near the diameter of the oil feed holes in the rebuild kit's journal bearing, but I might be able to double their diameter.

I could see a couple issues: too much oil flow could overwhelm the oil drain from the turbo to the oil pan, forcing oil past the internal seals and into the intake or exhaust. Excess oil flow through the turbocharger could lower oil pressure in the rest of the engine. The oil feed for the turbo comes off the exhaust side of the block, near the timing belt side. Oil pressure is critical on this engine with the flat tappet high pressure fuel pump driven off the camshaft. This potential for lower oil pressure might affect the pressure at the cylinder head.

I've not yet decided if I will try this modification. The good news is that I've got the old cartridge to practice on before I attempt anything on the new replacement cartridge. 

I welcome any comments, thanks. 

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## passsattdi (Aug 11, 2012)

Sandman333 said:


> These last three photos show a modification that I'm thinking about doing. If you watch the video on the product page at turbolabofamerica linked in the OP, you can see how much larger the oil feed holes are in their journal bearing vs the stock bearing pictured here:
> 
> 
> 
> ...


They may have increased the ports in thier kit to combat coking as long as possible on the rebuild. Ask them.

Ps This also would increase the oil in the shaft, increasing the cooling capacity on the oil side of things.

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## Sandman333 (Oct 28, 2002)

The turbine housing and cartridge both arrived yesterday. That's ~2 days shipping time from Lithuania. Not bad at all. There were no additional Customs fees or taxes due. 

Both parts appear to be quality pieces. I do notice some minor differences from the OE parts in my car, but nothing is too concerning. The biggest issue is that the external arm for the waste gate valve contacts the exhaust downpipe mating flange before the valve can open more than half way. I'm not sure how far that valve is supposed to open. It may be a complete non-issue. But, just to avoid any problems that would force me to pull the turbo after I get the car running again, I'm going to go to the local Harbor Freight and pick up some porting bits to remove material from the outside surface of that flange in order to give the waste gate arm enough clearance to articulate fully. It's just cast iron and all work will be performed on the outside surface, so it won't affect the internal air flow.

The new compressor wheel:









I was able to pull the wheel off without heating it with a torch:

















Comparison of the thrust bearing in the new cartridge with the kit from turbolabofamerica:









In these two photos you can see that there's a small ball bearing check valve port at the ends of the thrust face oil channels in the turbolabofamerica thrust bearing. These oil ports and check valves are not present in the OE part nor the new replacement. The thrust face oil channels are also longer in the turbolabofamerica part. I used their part during reassembly.


















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## Sandman333 (Oct 28, 2002)

More disassembly photos. Interestingly, the journal bearing in this new cartridge appears to be the exact same part as what's included from turbolabofamerica. The middle holes are both the same larger size and the extra holes at the outer ends are all there.

















































Don't forget to transfer the locating pin from the old parts to the new assembly. This serves to properly clock the hot side to the cartridge.












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## Sandman333 (Oct 28, 2002)

All assembled and ready to go back into the car. The only part I used from the turbolabofamerica kit was the thrust bearing. That's ok, it was a learning experience for me and Austin answered a lot of questions that I had. I feel it was well worth the ~$50 for the kit because of that, but if I were doing this again I would contact Austin and just buy the thrust bearing vs the whole kit. I also got a turbo install kit from ECS Tuning, which includes new exhaust downpipe studs and nuts, header nuts, and lots of gaskets and copper washers that make the whole process much easier. 


























Also, I used this tool to remove the exhaust header studs from the cylinder head. They worked great and made the job much easier. They removed those studs and tightened the new ones and the new downpipe studs without damaging the threads.

Assenmacher Specialty Tools 201 Metric Stud Remover/Installer Set - 4 Piece https://www.amazon.com/dp/B00063UMZ4/ref=cm_sw_r_cp_apa_i_n1VhCbPEA94YF

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## Sandman333 (Oct 28, 2002)

I've decided, just for peace of mind, that upon reassembly I'm going to use the following parts to make an oil pressure gauge at the turbo, off the banjo oil feed bolt. This will give me continuous information about the oil pressure reaching the turbo bearings. I already have a NSP boost gauge in a single steering column pod, so this will compliment that with the exact same colors.

https://www.ecstuning.com/b-new-south-performance-parts/20t-fsi-banjo-port/con017/

https://www.ecstuning.com/b-new-south-performance-parts/52mm-oil-pressure-gauge-kit-0-100psi/gau010/

https://www.ecstuning.com/b-new-south-performance-parts/mk6-dual-gauge-pod/pod026/

I'm also servicing the camshaft chain tensioner while the car is down. I already have those parts here, minus the stupid expensive 3 plastic sealing ring set. Of course one of those was broken when I took the housing off. Have to order that as well.

https://www.ecstuning.com/b-genuine...amshaft-adjuster-housing-seal-set/06f198107a/


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## NitrousOxide (Dec 5, 2017)

*Very well documented*

This is a very well documented thread, and I learnt very much from YOUR experience.
However, the moral of the story for me is that it is better to just buy a rebuilt turbo instead of even trying to go through ANY of the procedures that you did.

Sure, you got your hands "dirty", so that I didn't have to, but I do believe Borg Warner "knows" what they are doing when they designed the oil passages to be that specific diameter. Normally, one would agree with your temptation to drill out the oil passages, but the pitfalls your mentioned is equally real.

Yesterday, I ordered a rebuilt K04 (revision 701C) from eBay to replace my K03, so I'll see how that swap goes when it gets here.


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## Sandman333 (Oct 28, 2002)

Actually, I decided not to drill out those holes, not knowing how that would affect oil pressure in the rest of the engine or whether it might increase oil flow so much that it would overwhelm the oil drain for the turbo. I do think replacing the thrust bearing with one that has 360° of support is worth it, however.



NitrousOxide said:


> This is a very well documented thread, and I learnt very much from YOUR experience.
> However, the moral of the story for me is that it is better to just buy a rebuilt turbo instead of even trying to go through ANY of the procedures that you did.
> 
> Sure, you got your hands "dirty", so that I didn't have to, but I do believe Borg Warner "knows" what they are doing when they designed the oil passages to be that specific diameter. Normally, one would agree with your temptation to drill out the oil passages, but the pitfalls your mentioned is equally real.
> ...


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## Sandman333 (Oct 28, 2002)

Just wanted to post a final update; I did get this complete along with replacing the VVT timing chain and tensioner, VVT sealing rings, oil/filter change, HPFP cam follower, and installation of a Neuspeed turbo muffler delete and discharge tube. The car runs like brand new with plenty of power from the APR Stage I tune. I also installed a turbo oil pressure sensor (see pic below) and will wire up the gauge in a dual column pod (along with my vacuum/boost gauge) later. I replaced the 11 year old battery with a new one from my dealer ($140) and will need to replace the after-turbo exhaust sleeve/coupler here soon (for the second time). This will now become my DD car to keep miles off my truck.












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## NitrousOxide (Dec 5, 2017)

Does anyone know of any charts to show an improvement over stock of upgrading the discharge piping?

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## Sandman333 (Oct 28, 2002)

12k+ miles later and the turbo is working great, with a single caveat. Every so often I will get some turbo surge under WOT high boost conditions. I think I may need to add more preload to the waste gate. I tried to set the arm to the same length as factory, but it may be off just a little. I should be able to reach up under to there to adjust it without removing the turbo. 

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## silver06passat (Dec 12, 2011)

A very well documented and detailed thread. nice job!

JP


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## Norwegian Blue (Nov 24, 2012)

Just now I am rebuilding my K03 on my Mk5 Gti - I sourced an uprated kit covering the whole family of K03/K04/K07 turbos. 
My kit comes with both single feed and twin feed bearing housings - intrigued by the improvement of twin feed I started digging and found this image:









K03 is a single feed housing (right hand side), further digging highlighted a problem with installing a twin feed bearing housing will not work as the oil feed route will not allow oil to get to the oil grooves and then to the shaft itself - where it need oil most.

In short - don't do this mod!


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