Blagger's Guide to TSFI BWA Internals - Pt.1 Sump Removal

[Generic_Username]

By unpopular request, and because I've got the thing in bits, here's part one of how to dismantle your TSFI BWA engine. Removing the sump is, in my opinion, an important thing to do on an elderly TSFI due to the typically VAG habit of over complicated design backed up with really cheap bits (known as 'cost engineering'). Specifically, the cheap bit you really want to be wary of is the Balance Shaft/Oil Pump chain drive unit.

 

This masterpiece of cheap casting and tactical application of rubbish plastic is entirely responsible for the health of your high performance, daft oil service interval engine. Without it, the oil don't pump, and when the oil don't pump, the cam chain tensioner doesn't tension, and then that eats itself... and half the cylinder head with it... and probably the turbo as well... and maybe even the spins the mains bearings too. Good job VAG engine designer chap. Not.

 

Anyway, here's a pump chain tensioner and chain I prepared earlier;

 

’

 

The more eagle eyed amongst you may not the fact it's in many bits, and I now have several chains, rather than just one. It works on the same basic principle as the cam chain tensioner - oil pressure pushes the plunger out, forcing tension into the chain. This in itself is a self defeating design, as there will always be a moment or two at start up before sufficient oil pressure is present to tension the chain fully. Anyway, this lump of tat sits between the two sprockets on the balance shaft unit (full details in part 2 of the guide) and is driven from the crank sprocket, which is at the end of the crank... but, we're a long way from that, so here's how to remove the sump.

 

Tools required:

10mm hex socket and extension bar with wobbly end.

T30 Spline bit

5mm Hex/Allen bit

16mm hex socket.

One of these;

 

It's a Teng 510505 - importantly it is a long reach 5mm hex with a rounded end. If you're gonna do much to this engine, I'd recommend investing in one of these - it's a very useful thing, and the BWA is covered in 5mm hex bolts in awkward places

 

Lastly, appropriate Tea, smokes, gloves, and rags for mopping up.

 

Parts Required:

Sump sealant

Return Pipe Gasket

Sump bolt (yeah, I know nobody does this anymore, but I'm old school)

 

Step 1:

Remove oil from engine - personally, I like to put most of mine in an oil catch pan, with some up my sleeve, so that I give off the subtle aroma Eau D'5/30 all day. Remember to place the full catch pan somewhere where you can trip over it later.

 

Step 2:

Unplug oil level sensor from rear underside of sump

Unbolt the Aux Water Pump mount from the front side gearbox end of the sump (5mm hex)

Unbolt the charge pipe from the cambelt end of the sump (T30 Spline) - note, you don't need to remove this to remove the sump. However, if you're going full strip down, it will get in your way later.

 

Unbolt oil return pipe from back of sump. It will drip oil (this is where your sleeve comes in handy). It's on a flex mount from the turbo above it, so okay to leave it hanging there.

 

Step 3

Unbolt bellhousing bolts holding gearbox to sump - 3 x 16mm hex (big bar recommended)

 

Step 4

Unbolt sump bolts at the locations shown below using 10mm hex socket.

 

 

Now, contrary to what all the internet experts said, I didn't need to cut half the gearbox out to get to the two bolts on the gearbox end of the sump - simply crack the nuts with the 10mm, then use your shiny new Teng long 5mm to get them out as VAG conveniently put 5mm hex inserts in the nuts. They will probably drop into the cavity behind the flywheel, but easily retrieved once the sump is off.

 

Step 5

Remove sump - nothing more than a tap with a Technical Adjuster (aka hammer) should crack the sealant. It will drip oil from everywhere, so be prepared.

 

Step 6

Clean/inspect Sump.

 

The inside of the sump is unremarkable - there's a plastic surge plate at the back, which can be unbolted and removed, and that's about it. However, if you're a trackday fiend, it is worth considering that it is entirely unbaffled - the only thing stopping the oil swimming about is the balance shaft unit, which sits fairly low. However, you can see the tidemark of the oil after cleaning in the photo above, so there's plenty of space for it to slosh about.

 

In terms of cleaning - I just got stuck in with engine degreaser and an old toothbrush. After that I filled the sump with boiling water and chucked in a few dishwasher tablets to breakdown any remaining oil and more importantly remove any degreaser residue. You don't need to clean it - mine was full of bits of chain and tensioner - but a clean sump is a happy sump.

 

Conclusion

A simple job, and cheap in terms of parts required for refitting. The ancient art of Sump Divination is almost lost these days, but you can tell a huge amount about the mechanical health of an engine by what's kicking about in the underbelly. Also, for the sake of a couple of hours of oily fun, you'll get to see how good or bad your tensioner unit is.

 

Tune in next time for the really interesting/scary bit which is the balance shaft unit.

 

Dunk

Edited 14 February, 2017 by Generic_Username

[Guest]

Its not applicable to me, yet. However an interesting read and looking forward to more.

 

It's how a workshop manual should be :-)

 

Good work.

[RichieXR2]

Looking forward to this, subscribed. 

[Generic_Username]

Can someone pin this? I can't edit the main post now, so can't update the title.

 

Right then Laydeez and Germs. Tonight's main attraction for your viewing pleasure! The legendary! The mythical! The thing that everyone fears!

 

The Balance Shaft unit! (gasps and screams from the crowd)

 

Now. In the world of internet, where everyone is an expert on everything, the balance shaft / oil pump unit seems to have taken on mythical status as a beast of such fiendish complexity and hideous cost, that to merely touch it is to invite a bill for many thousands of pounds, cause divorce and premature baldness, and maybe even make you cry.

 

As I've been ripping combustion engines apart for nigh on 30 years, and was tuning GM C20LET lumps from Calibra Turbos to 340bhp+ and putting them in Opel Mantas before VAG even considered making this engine, I've no such qualms about this sort of activity. Also, I've never needed to know what a balance shaft unit did until now, nor have I ever owned an engine with such a catastrophically silly arrangement of pumping its oil. So, let's run up to the King of Terror and knock his crown off, shall we?

 

Tools Required

10mm Hex socket

5mm Allen key

M12 Spline bit (a real spline bit, and not the star bit I called a spline bit in my last post)

Oil Catch pan

Rags.

More rags.

Tea

Smokes

Gloves

 

Parts Required

Balance unit bolt kit - they're apparently stretch bolts, and for the sake of £20 or whatever they are, bit of a false economy not to.

Chain tensioner unit and chain

Crankshaft sprocket

Oil pickup pipe + o-Ring

 

Step 1

Having removed the sump, you'll now be presented with the underside of the balance shaft unit. On the cambelt end there's a plastic cover - pop this off, and you'll have a view that looks like this;

 

Key

1 - Oil Pump drive sprocket

2 - Balance shaft drive sprocket

3 - Tensioner unit

4 - Tensioner

5 - Oil Gallery Bolt

 

There should also be a chain in this pic, but mine was either wrapped round the crank sprocket (out of shot, up behind the crank pulley. More later), or scattered about the sump.

 

The whole unit itself is held in with 10mm bolts, apart from one M12 spline down the gearbox end. Before we unbolt it, you need to compress the tensioner (4, and green dot below) and insert a retaining pin/nail/2mm hex key

 

Unbolt the three bolts (yellow dots below) holding the tensioner on, slide chain off the sprockets (if your chain is still there), and then unbolt the balance unit. When you unbolt the front corner bolt at 5, you'll open up an oil gallery which seems to contain about 1/2 a litre. With a bit of wiggling, allow the balance shaft unit to gracefully fall on your bonce, covering you in more oil.

 

 

 

Side note: Having drained the sump before doing this, I had at least another 1/2 litre of oil drain down or was left in the balance unit. Including what's kicking about in the head, oil cooler, cam timing unit, and so on, you'll never do a proper oil change on one of these engines - which makes the long life interval scheme even more crazy

 

As you take it off, remove the spacer plate and baffle - red and green dots.

 

Now place it upside down over the catch pan for a while... go make a brew or something.

 

Step 2

 

With the unit upside down, unbolt the pickup pipe (5mm Allen) and place somewhere where you won't stand on it. If cleaning it, let it soak in cellulose thinners or degreaser.

 

Get a light, and peer down the hole

 

et Voila! Pump, oil, for the use of.

This is a common or garden rotor pump. Nothing particularly special about it - but mine seems to have a bit of marring on the faces of the outer rotor. This could be from startup starvation, it could be from when everything went south. If yours has pitting or deep scores then it might be on it's way out. You can remove the pump sprocket and then remove the pump itself to get a better look, but I'm not getting into that yet.

 

Rotate the pump sprocket and watch for any uneven or lumpy rotation.

 

Step 3

Flip her over, as they say in the more high class establishments.

 

Green Dot is the primary shaft for the balance gear. Note that it is not connected in any way to the oil pump on the left. The oil pump's only connection is via the chain - it just happens to sit in the same unit.

 

Blue Dot - this is the primary - secondary gearing. Although it looks like the primary shaft is one long unit, it isn't. The primary is geared 2:1 over the secondary. The second row of gears are the counter gearing to drive the other balance shaft contra-rotationally.

 

Red Dot - balance lobes. These are fairly hefty items, and are driven contrary to each other - so one turns clockwise, the other counter-clockwise. This system ensures you get a lot of balancing weight at TDC and BDC - which is the vibration you're trying to damp out from the crank/pistons, but as the weights oppose each other for the rest of their rotation, they cancel each other's vibration out front to rear.

 

Gearing:

 

The crank sprocket to primary shaft sprocket appears to be a direct 1:1 drive (I'll confirm when I get the timing case off). The oil pump sprocket has more teeth (again, I'll count later) and will run slower than engine speed - guesstimate about 80%.

 

The balance shafts are geared up by 2:1 - so for each full rotation of the primary shaft, or 1 engine rotation, the secondary shafts rotate twice. Which is food for thought when you spaz the old bus round to the redline - at 5500rpm, those little shafts are doing 11,000rpm

 

That the weights are TDC and BDC twice per engine revolution suggests to me that there's some funky crank angles between the pistons, so that's something else I'll have a look at.

 

Checking

 

Unless you're prepared to pull the thing apart (which I'm not going to do just yet) the basic checks are for signs of shaft float by looking at either side of the shells to see if there's a clean patch where the shaft it moving about. Rotate by hand and check for smooth rotation and no flex or deflection in the sprocket. Also check the gear teeth for pitting or cracks. For the home mechanic, that's about your lot.

 

Personally I'm confident I escaped with just a mangled chain, tensioner, and crank sprocket this time, but might send it off to Powermax or someone to get it checked out professionally.

 

Conclusion

 

Despite the mystique this thing has attracted in some VAG circles, there's not a lot to it really - it's a big box with some spinning weights and a rotor pump placed in the corner. Given the speeds involved in the thing, poor engineering would result in some pretty spectacular failures, but that's equally applicable to everything else in an internal combustion engine - putting a rod through the block is infinitely more terminal that the balance shaft unit failing.

 

However, it is worth remembering that this unit is an evolutionary afterthought - the bottom end wasn't originally designed for a unit of this size, and driving the thing by chain, itself tensioned by an oil pump driven by the same chain, is an engineering bodge, and a failure waiting to happen.

 

Also worth considering is that the chain is responsible for speed governance of the balance shafts - so when you super fast shift slam it from 2nd to 3rd at 5,500rpm, the chain is going to haul down that reciprocating weight from 11,000rpm to whatever. This will cause chain slap, which over time will cause wear to the tensioner unit. That said, given that the most likely failure is the chain, and that the oil pump is an isolated unit within the assembly, it should be unusual indeed that the pump fails.

 

But... as soon as that pump stops pumping, you lose camchain tension, and the high speed turbo gets starved of oil... and that is a bit of a problem.

 

The irritating thing is that VAG/Skoda confirmed that the oil pump can't be bought separately, as it's "a matched unit". In my opinion, this is a bit of a stretch - it's a rotor pump running around 80% engine speed - so probably max rotation would be around 5250rpm, driven by a chain and tensioner, and the whole pump can be unbolted and removed... it's not that much of a precision instrument.

 

Next step - get the timing case off... which is behind the cambelt.

 

[Ollyk]

Any updates to this topic at all?