BMW Diesel Turbo Tear-down and Re-assembly. Can you DIY rebuild your BMW diesel turbo?


Tearing down and rebuilding the turbo in
your diesel BMW – is that even worth considering? Hi I’m Steven, I hope you’re good, and
welcome to my channel, or maybe even welcome back to my channel. Today I’ve
been tearing down, and rebuilding the turbo from a diesel BMW maybe you can too!
This particular turbo is from the m47 series of engines, but it’s basically the
same as all of the turbos in diesel BMWs. The basics are the same, so follow
along as I do all the steps, with a bit of explanation about what the parts are,
and how the turbo works. You might find that you want to do it too one day.
There’s a lot to do, so we’ll be moving quickly to squeeze it all in. Let’s
get on with it! Start with the main parts of the turbo: we have on the left there
the electronic actuator, on top the aluminium part is the compressor housing,
in the center connecting the two impellers is the cartridge –
it’s where the oil flows in and out, and on newer turbos that’s where the coolant
flows in to keep the bearings cool as well, and on the bottom we have the cast
iron section – that’s the turbine housing, that’s where the exhaust flows through.
Now to how it works, briefly. We have the exhaust goes in to the turbine housing,
spins the impeller, and then it comes out. On the top we have the fresh air in from
the air filter, and then that is spun by the compressor impeller, and that is then
sent off under pressure into the engine. And now for the super tricky part of a
diesel turbo in a BMW – and that is the variable geometry system, or the variable
nozzle system. In the center we have the actuator, and that controls the actuator
arm there on the right hand side, and it’s pin, and that pin connects to the
nozzle ring on the left. Inside that nozzle ring are the veins which, I’ve
colored in orange, they’re hiding inside. I’ve given you an x-ray view
there. So by adjusting the angle of the vanes this turbo can control boost over
a very large part of the rev range on our BMWs.
Preparation. This is preparation for pulling this thing apart. What I’ve done
is I’ve got my favorite color there, and mark the bolts. I don’t know the torque
settings for any of these, I don’t have a workshop manual on this turbo, so what
I’ve done is I’ve marked all the bolts so we can put them back to exactly where
they were, and also you’ll notice the housing, the exhaust housing there, the
turbine housing, is marked with a big blob as well – now that’s just in case…
just in case there’s no dowel pin, no locating pin on this particular turbo. If
it’s a BMW original equipment turbo it probably is has some good locating pins,
but if you’re dealing with some sort of aftermarket, or specially modified turbo,
there may be nothing to mark the location of where it sits, so you need to
mark it yourself. Start by removing the turbine housing, which is the big cast
iron part in the bottom of this picture. Now a bit of a bit of your favorite
penetrating oil there, just to make sure that things are as loose as they can be,
and then we take away the very small bolts holding this together. Now the
little bolts need an 8 millimeter size spanner, they’re not torqued up that
tight, as you can see a bit of a thump on the spanner and they come loose, mainly
stuck due to a bit of rusting perhaps, and now you can see I’ve got to the one
I can’t get to, that’s because the actuator is in the way, so what we’ll
do is we’ll just take that actuator housing out of the way a little bit, so
we can get to that bolt. Because I’ve marked all these bolts we mark the order
of them as well, so each one is marked with a number 1 to 6, so when we put them
back in the nail varnish, the marking pen I should say, the marking pen will line
up perfectly once we’ve done them up to the correct torque.
Now some may say that I should use a torque wrench, but there was no way a
torque wrench will fit him there, and if you use an adapter on a torque wrench
the readings are completely useless anyway. There’s not a lot of torque on
these, they’re mainly just to hold everything in place. The sealing is done
by a gasket, and by an interference fit. Now here comes the tricky part – now
there’s no way this housing is coming off, unless you hit it with a big hammer
and I’m not going to do that because it’s cast-iron, and there’s a good chance
that will crack the cast-iron, so I’ve developed a little system here using
some galvanized nuts, and some threaded rod, and you can see there that
fits over there the bolts that go into the top part of the turbo, the top in
this picture, goes into the compressor side, and it sort of spreads the load, and
then I can adjust the threaded rod out a little bit, and then using some bolts
that I’ve specially cut to just fit in the gap, I can use that to push the two
halves apart. Now for people that work on these turbos every day, they probably
have a big piece of plate steel they use that’s cut just to the right
size, but for me this is my improvised solution. I’d love to hear what the
professionals use, but this does a nice job of pushing the two halves apart, that really are stuck. They weren’t going anywhere.
Once you get soot and carbon buildup in these diesel turbos, sometimes they’re
very difficult to get apart. It’s not like some turbos that just have a V
clamp. These are well stuck, so as you can see, keep turning that, and it’s pushing
the two halves apart, without any hammer blows, without any screwdrivers pushing
in there to ruin your gaskets. Once that’s apart, we take all those
little improvised tools out of the way, and then we can separate it. Okay are we ready? Over it goes! There we
have it – turbine housing off, and in fact it
doesn’t look too bad, it’s not too clogged up,
it looks fully functional. It could do with a clean of course, but I’d say there’s
nothing wrong with this particular turbo in that regard, you can see the veins
operating there. The next part of the job is to take out the
nozzle ring. Okay, now we’re removing the nozzle ring, which is this strange
conglomeration with the veins in it. Get a bit of penetrating oil in there, just
to see if it helps, try and give it a wobble, there should be nothing holding
that in at al,l so it should just pop straight out, however in these diesel
turbos that run it with lots of soot in the exhaust, it clogs up everything.
That’s great for sealing everything, but it’s not good for removal. Now try some
light blows with a nylon dead-blow hammer – that’s not working, a bit of levering –
that’s not working. Okay this is nozzle ring removal attempt number two! Okay,
I’ve gone a bit drastic here – I’ve got a three jaw puller – we’re gonna use that. I
don’t like this solution – I’d like to hear what other people have used, I want
to know of a better solution I don’t like putting pressure on bearings inside
the turbo cartridge, it makes me very nervous putting that much pressure on
the bearings when we’re not trying to remove the bearings. So I’d
really like to know of a better solution, that doesn’t involve this nor
involves hitting with a hammer, because of course, if you hit hard enough with a
hammer and you miss, you take out the some of the blades. So here we go, let’s
get this thing…will it come off, big breath, hold it, yes, perfect!
We’re in business! And off it comes, there we go.Okay, it’s inspection time! As you
just saw, under there is surprisingly soot-free. That gets a lot of
temperature, especially in cars that have a particulate filter that needs to be
cleaned by the engine management system, and that puts extra temperature into the
turbo, and into the exhaust, and that really does help keep things clean, so
chances are if you permanently take off your diesel particulate filter, you will end up with
a dirtier turbo as a result. That ring, that VNT ring, that variable nozzle ring
looks really quite good. Now to inspect, a quick inspection of the in and out oil
hoses. The one on the left is the engine oil going into the turbo, and the one on
the right is the drain out the bottom of the turbo. Now just check the rubber is
in good condition with these, make sure there’s no cracks, or that it’s gonna
break. Now one thing note: it’s often
recommended that when you change your turbo that you change the inlet oil pipe,
because it can get completely blocked up. If your shaft is wobbling, and your
cartridge needs to be replaced, then you need to replace that oil line as well.
There’s a couple of washers on that oil line, make sure you put them back, and if
they’re pitted or in bad condition, then they should be replaced as well, but if
your turbo is in good condition, chances are you can reuse all of the
gaskets, they’re made pretty tough, and you’ll know, you’ll know quickly
whether they’re damaged or not. Okay, we’ll move on to cleaning these
components. So in they go, all the exhaust side, the nozzle ring, the exhaust housing,
your turbine housing, into the ultrasonic cleaner. Half an hour later at sixty
degrees with some carburetor cleaner, and everything is a lot better, but they’re
still residue, and there is a little bit of carbon on there, so we’ll get out our
3M brand pad, our Scotchbrite pad, and just go over
everything, give it a good old rub. Each time I’m doing this,
I’m using some more carburetor cleaner out of the ultrasonic cleaner – that works pretty
well, and as you can see gloves are required unless you want very, very dirty
hands. Once again we’ll grab the housing give it a good scrub, just to make sure
when we put it back together all of the parts match up nicely without any gunk
in the way. Well gotta have a clean sink… Okay and
finally this metal gasket is in perfectly good condition, it’s got no
pitting, it’ll be good for another few years at least. I’ll give that a rub
too and get it ready for re-installation. Perfect! And finally this is the harder
bit to clean, because I can’t just put this into the ultrasonic
cleaner because it’ll get liquid into the bearings and whatever, so we’ll just
scrape, we’ll just scrape all this off, and once we’ve done the scraping we’ll
be able to try some other bits and pieces, try toothbrush. more scraping, get
the scotchbrite pad out there and give it a good rub, each time we’re using bit
more carburetor cleaner. There we go, that’s looking
a lot better. Yes, fantastic. No more cleaning, thank you. Now for the
compressor housing removal. This is if you have a wobbly shaft, and you need
to replace the central section of the turbo. Now the a cartridge section
contains both the impellers, both the exhaust turbine impeller, and also the
inlet compressor impeller, and they’re connected together. Now, of course, it is
possible you could replace individual impellers, but the fact is, you’d need a
balancing machine and they usually cost upwards of $10,000, so it’s not something
you’re going to have at home. So first of all we’ll take off the bolts holding the
compressor side on, and take off the actuator housing because it was in the
way, and then this should come apart easily. This side doesn’t even have a gasket, it
just sits there. Yes, spoke too soon. Okay let’s give it a
little persuasion with the dead-blow hammer. yes there we go,
this side comes apart very easily, even on these diesel turbos. You can see there
that we have our compressor impeller on that side. Now you can buy that component
separately for most turbos, and that’s a lot cheaper than buying a new turbo. In
this particular turbo, there’s nothing wrong with the compressor side, the
housing is in good condition, it’s not scratched up, we put it back together,
you can see the locating pin. Being a BMW part it’s well located, so we didn’t
really need to use our marking pen, but it’s good idea, a good habit to get into.
It should go back together nice and easily, just pressed in with fingers, and
then we can do the bolts back up. Once again we’ve marked each bolt number, and
we put them back in their respective holes, and we can do them up until the
markings line up again – that’ll get us pretty close to the perfect torque
setting. I think doing these up – most the match up
perfectly, I think maybe some of them went half a millimeter further round
than what the marking was, so really it gets you very very close. If you find
they don’t line up anywhere near close then you know something is wrong. Okay
back on with the actuator housing there, re-attach the actuator, and I’m good to go! I’ve even marked these bolts so that I
can tighten them up to pretty close to what they should be as well. There you go. Everything working! And now that our
turbine housing and nozzle ring are all clean, we’ll put them back together. Now
there’s three little machined out sections on the turbine housing, and that
mates up perfectly with the nozzle ring. It’s got three sections there. Where the
actuator connects, there’s a little flat section on the housing, a flattened out
section, you can see it now, right at the bottom of the screen, there we go, and
that’s where that goes around, I don’t think you can get it wrong, it only goes
in one way, so we’ll just shake that in a little bit until it clicks in. There you go – all sitting nicely. Now there’s a pin, there is a locating
dowel pin, and it lines up with the gasket, and also with the identical mark
on the cartridge, so being a BMW part number they don’t let you make a
decision about where you line everything up, it’s lined up for you. Now the one
tricky bit here is that you have to locate the actuator pin with the appropriate
part of the nozzle ring, and that’s the tricky bit, so have a look as you’re
doing this to make sure that pin goes into the ring correctly, otherwise it
will not go together nicely. Now I’m not going to tell you it’s going to
fall together perfectly, easily, it’s going to require a bit of wiggling, a bit of
looking, and a bit more wiggling, and it’s still going to be a little bit tight. But take your time with this section,
make sure nothing is is sitting wrong, and even after that it’s just a
little bit, a tiny tiny bit out of alignment, that pin isn’t perfectly
aligned, and now it’s sort of half stuck so we’ll just give it a slight tap just
to align the dowel pin with the cartridge. We’re talking small taps here,
with a very very light hammer, and there we go, we should have alignment. Let’s see
if we can get it closer look at that. Yes, there’s the pin – you can see
everything is in alignment. Make sure the actuator is working, it’s
not stuck, and then you can put our bolts back in, in their respective holes. Let’s get this done up, work your way
around just to make sure it’s even pressure. This isn’t falling together, it
does require a little bit of turning, nothing excessive, but not nothing either.
It’s not like the compressor side, the tolerances are a lot tighter because the
pressure inside the exhaust side is a lot higher, as you don’t want any leaks
on that side – so they make it fit very very snugly. Work your way around,
I’ve got my little ratchet there to make work a bit quicker. Once you’ve finished, all
the dots should line up. This is for the actuator, now these are two pretty
identical turbos, but the positions they came from the workshop, the professional
turbo repair workshop, would you believe they came back with their
actuators in different positions – one has the position 1 millimeter different to
the other, so somebody’s not done it right, or maybe both of them haven’t done
it right! There is a Honeywell machine, probably other brands as well,
where they emulate the BMW computer, so that they can locate these veins
perfectly on the fully open, or fully closed position. What I’ve come up with
is a quick and dirty way of getting this actuator set correctly. If your
actuator is calibrated badly, your turbo won’t come in at the right time, maybe
it’ll come in 200 rpm later than you expect, so it’s pretty essential. Now the
way I’ve come up with to calibrate this is using the cars own calibration
routine. Every time the car starts it does a check. What we’ve done is we’ve
taken the turbo out, put it on top of the engine here so we can connect up the the
harness, and as soon as you, push the actuator in there, as soon as you open
the doors, look what happens. There we go.
Actuator actuates! And it holds with a great deal of pressure the veins in the
fully open position. So what we can do here, is we can check,
with the turbo partly disassembled like this, we can check that that actuator pin
up the top there is also in the fully open position.So actuator is saying
fully open, we need the pin to be matching that, and you can see we can
turn that part of the actuator until it is sitting in just the right position, and once we have it we’ll put the nut on
the end, the right way around, and try it again just to make sure. Give it a little tighten, okay, let’s
see how that’s going. Eventually this times out, so you have to
hit the key again, so reset it there, we’ll hit the key again, there we go – have we got the pin in the
right place now? Let’s have a look – is it… we want it at the far end, but not
jammed against the far end. A little a little bit of adjustment
there, and I think that’s about perfect. Yeah, that’s just where it needs to be. Now, like I said before, this this is not
the perfect way. There are calibration machines to do this, but my experience
has been that they not always used by the people who should be using them, or
at least maybe the calibration machine is needing calibration. There we go, we’re in
business! We’ll put it back on the bench and
compare it with the one I know is working fine, and you’ll notice now that, just tighten that up, that it looks like it’s sitting a lot more like the other
one. Now there’s not a one millimeter difference in calibration
between the two they look pretty much the same. We’re on to the final check
before we put this turbo back in the car. Just make sure that everything is
rotating, that we haven’t somehow jammed something in our reassembly process,
bolts are all lined up with where they should be. You can see that the actuator is free moving
from one end to the other without jamming anywhere, so this turbo is ready
to go back in. When you put the turbo back in the car, it’s very important that
when you attach the oil way, the top oil line, that you fill it with oil before
you attach it. This section is called external cleaning and painting. But I’m
just joking… This turbo is not seen, you can’t see it
so there’s no way I’m going to clean it and paint it, and that’s that’s all I’m
going to say about that! If you feel like cleaning and painting your turbo, be my
guest! Well that was certainly a lot to cover.
If you liked this video, give it a like and consider subscribing to my channel
to see more videos like this, maybe not quite as long as this. If you think your
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10 thoughts on “BMW Diesel Turbo Tear-down and Re-assembly. Can you DIY rebuild your BMW diesel turbo?

  1. Nice video. I would suggest pick up the pace a little bit since it may keep the interest of new viewers while not overwhelming someone attempting to do this their self and follow along.
    Best of luck.

  2. Hi Steven, What size is your Ultrasonic Cleaner as I’m looking to buy one and I need to make sure my Turbo housing will fit. Looking at a 3L one.
    Cheers,
    Steve.

  3. I love you’re content really detailed and informational can I ask if you one thing can show us how you took the turbo of from the car if you ever get the chance too please thank you so much for the BMMER Diesel content

  4. Use a map torch and heat the aluminium housing, should expand enough for ezy removal.. lot of wd40 first though

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