2.5 V6 TDI (Euro/UK) info repository / knowledge sharing thread

[d24tdi]

I am starting this thread as an attempt to create a gathering point on here for owners of the 24 valve 2.5L DOHC V6 TDI engines sold outside North America, so that we can consolidate and organize information, resources, and experience. If it is successful, perhaps moderators can pin it to the top in this sub-forum so that the info will be easily found for others.

Given that this is mostly a North American forum and the engines were never available here, info on them seems to be pretty thin and scattered, and gathering details elsewhere can be tough. However, for years or decades there have always been a few folks here that are focusing on them (either as imports or some overseas members), and I believe there is currently a small but active group on here that is owning and working with them today.

Members I know have background in these engines who have been recently active that I will page here -- please add others if I am missing any:
@adamss24
@quattrosun
@ben0069
@diffas
@IndiaRed
@Mikkijayne

As the B5, B6, C5, and D2 platform cars that originally came with these engines age into compliance with the US NHTSA 25 year import rule (and they are already long ago legal for import under Canada's 15 year restriction) maybe we will see more of them, and needless to say they are already familiar in Europe and the UK for the small group of members here who run them over there. My own situation: I currently have an already US-registered 2004 Passat wagon using this engine that has some engine, turbo, and fuel system issues I will need to try to work out and learn as I go. I also have a few other loose 2.5's and related parts I have collected the last few years with intentions of having some local spares on hand and eventually swapping one into my 2001 Audi Allroad. Now that I've wasted enough time getting started on that project to the point that 2001MY is just about legal for import, that swap may never happen, as I am taking steps now to bring in a factory Allroad TDI from Europe as soon as it's eligible. So it's time for me to start climbing this learning curve. I'm hoping this will become a place someone in my position, getting up to speed on an unfamiliar engine for the first time, can find the help they need. I believe quite a few of these engines have been swapped into other vehicles as well in North America -- Porsches, trucks, Land Rovers, etc.

This thread may be a bit of a work in progress to get it started. Some topics that I think would be worth trying to cover, though:
- A list of all 2.5L V6 engine codes, applications/years where they were originally used, and differences that define them (power/torque settings, injection pumps, valvetrain, engine management, emission controls, turbos, injectors, etc)
- Interchangeability of minor and major components between different engine types: which injection pumps, injectors, heads, turbos, induction systems, etc are usable on which engine codes?
- Tuning considerations, for those interested in it
- Maintenance and solutions to common problems (VP44 pumps, cams and followers, oil return check valves, CCV breather systems are some of the trouble spots I know of)
- US and Canadian overseas importation resources and experiences
- Parts sources for worldwide availability
- Special tools, service and repair procedures, how-to guides
- Factory service literature, wiring and parts diagrams, etc (I'll try to create a media library for this)
- Other resources/networking to link with good information on the 2.5L engine (other forums? other languages? Facebook groups? etc)

I will also compile a list of recent and less-recent threads that have involved this engine. Here are a few to begin -- and I will try to copy and paste here some key info that emerged in some of these other recent V6 discussions:
@IndiaRed's 2.5L conversion into a B5 A4 Avant about 10 years ago: https://forums.tdiclub.com/index.php?threads/audi-2-5-tdi-conversion-into-01-a4q-avant.443296/
@quattrosun's recent reconditioning and engine swap in a B5 A4 Avant: https://forums.tdiclub.com/index.php?threads/2-5-v6-quattro-b5-engine-swap-and-stage-2.536623/
Injector upgrade discussion: https://forums.tdiclub.com/index.php?threads/nozzles.409313/
Another older injector nozzle discussion: https://forums.tdiclub.com/index.php?threads/2-5-v6-tdi-injector-nozzles-cummins.234614/
And another on injectors: https://forums.tdiclub.com/index.ph...ace-683-nozzles-to-fit-v6-tdi-engines.299054/
Big power builds discussion: https://forums.tdiclub.com/index.php?threads/the-most-powerful-2-5tdi-v6.298614/

(please share links to additional threads others know of and I'll add them here too)

Cheers and hope this proves to be a success! Hope others who are in this small community will introduce themselves here too and we can gradually work on putting more info together.

 

[d24tdi]

Reserving the second post for more future info storage

 

[d24tdi]

And the third as well

 

[diffas]

For best outcome I recommend to go upgraded version of 2.5tdi, like BDG, BDH, BAU etc.

 

[d24tdi]

For best outcome I recommend to go upgraded version of 2.5tdi, like BDG, BDH, BAU etc.

Thanks for the input. Can you expand a little further on why you recommend those later engines and what all the exact differences are? Roller valvetrain the main reason, or are there other factors also?

One of the things I am hoping to accomplish in this information gathering/consolidating project here is an index of all the differences between the various V6 engine codes. Unlike the 4-cyl engines, it seems like there is a very large number of different engine codes (even for engines that seem to be extremely similar with same power ratings and configuration), and what they do and don't share is hard to keep track of.

For example, what sets apart a BDG from a BDH? I believe they are both 163hp versions used in FWD B/C platform cars..... But is there a difference between them? Parts that are compatible or not? Emissions/software? And what about the 163hp BCZ, how does that compare?

I know the BAU is the 180hp version of the late style engine.

Similarly -- what is different between an early 150hp AFB vs AKN? MSA vs EDC engine management is the only external/visual obvious difference I can find between the AFB and AKN I have here.... Is there more?

Thank you for the reply!

 

[d24tdi]

I will ask a direct question here too (@adamss24 maybe I can ask you this as well?):

The only running V6 in a vehicle that I currently have here is the BDH in my 2004 Passat. It has starting and driveability issues that I have traced to a timing control failure in the VP44 injection pump (appears to be stuck in retarded position, common failure on the Cummins applications too). I have three parts engines: an AFB, AKN, and BCZ. All three are supposedly running engines and complete with the VP44 pump.

Can I pull the VP44 off any of those engines and install as a replacement for the apparently failing unit on my BDH? Compatible or no?

Thanks!!

 

[diffas]

BDG and BDH are basically identical engines, one is 163hp and other 180hp. They are the latest versions.
Valvetrain is way better on newer, bottom end is stronger. BAU, BDH, BDG, BCZ are all with roller valvetrain and with stronger bottom end.
They have as stock form slightly better valvesprings so it takes more abuse than older generation engines. To be honest I had some years over 300hp on AKN with BDG heads daily so if you are not going silly with power and torque then its fine too. You can easily swap heads, they are bolt on.

AFB and AKN are both "msa" type of ecus, some weird edc15 and msa hybrid.

 

[d24tdi]

Great details, thank you.

Are all the roller heads the same, and all the sliding finger heads the same? Or do the 180hp heads have differences versus the lower HP heads of the same type?

 

[diffas]

All roller heads are the same. In engines there are some minor differences like different style plugs etc. Egr stuff is different but bare engines and heads are all swapable.