M57 330d Big Turbo | Bosch CP3 R90 rebuild

This is not a comprehensive guide by any means. It is just a primer to show you the inside, to make the task seem less daunting.

Most of the media from the rebuild process is on my laptop, this is all i could find saved on my phone still. I hope it gives you a good idea. It's quite a simple process, and with some common sense you can figure out the bits not shown step by step. If you can't, then with greatest of respect, don't attempt (may do more harm than good).

I am not convinced a typical refurbed r90 pump selling for £400-600 from some sellers is anything more than a basic inspection, reseal (as shown), clean up with paint, then tested on flow bench to confirm pumping capacity is within spec - seriously. New pump body core's are not available, and unless someone is machining the bore and supplying new oversized matching piston/plunger/cups to suit, then this is also not the done thing for a refurbed pump (hint, those that do sell for eye watering prices as a "stroker" pump, typically in American truck community market). Sooooo.... why are you paying someone an extra few hundred pounds for a few hours diy?

The seal kit used here is about £25-30 on Ebay, genuine Bosch kit's are similar priced if you have a service centre near you, and it takes a few hours to DIY rebuild.

Only special tool used was the bearing puller but even that isn't needed, I pulled one open by (carefully) prying with screwdriver and by hand. The shaft seal needs careful finessing as shown, then driving in carefully with mallet and suitable sized socket. There are some check valves with ball bearings, the kits come with new ones to replace so don't worry if some go AWOL on removal.

It's good practice to test the FCA - it's a simple solenoid and now would be a good idea to carry out the "Relentless Diesel FCA mod" (Google it) if you want. Additionally, the delivery valve in the back of the pump (connects to the rail) can be modified too - I will detail this separately at a later date (basically helps hold rail pressure for longer).

As long as you aren't a total ape with feet for hands, it's unlikely you'll pull out the input shaft out or over torque anything. Thus its not very likely you'll screw the rebuild up AS LONG AS YOU KEEP IT CLEAN INSIDE (you'll ruin your injectors otherwise!). I wasn't convinced if it was worth the risk to rebuild as the pump was immaculate inside and the seals looked healthy.. but in hindsight it was worth it, and i recommend it if you feel confident in your ability.
The pump is working well for 7000miles so far. The tolerances are so fine within that any slight deterioration/internal leak will see noticeable decline in pumping efficiency, so it's worthwhile if you are due to fit the pump. I wouldn't remove one just to rebuild unless it's totally FUBAR.

At the very least, you should open the pump cover of any used pump to inspect (could be full of rust), or ideally send to a shop to have inspected and tested either way. I didn't send mine off for testing YOLO, it has proved itself via logs...

If there's any sign of rust inside, the pump is no good. Fit only if you want to remove it again.