Typical 2.0 TDI problem - oil pressure is low

[Christian96]

Hello!

I have just taken out the balance shaft unit of my car since the "Oil Pressure is low. Stop engine" was flashing when exceeding 1850 ++ rpm.
The car was shut down immediately, and i think both engine and turbo survived (no funny noises).
The oil level was anyway right and was not polluted by metal. The oil and pressure sensor was then replaced, but the low oil pressure is still around. I measured around 0,5 bar.

Then further investigation was needed and I removed the oil pan and inspected the chain/gear driving the balance shaft module, in my case gears.
In my opinion, they seem fine?

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So the balance shaft unit was taken out. And I think the fault has been located.

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(The hex pin as showed is driving the oil pump from the balance shaft, and the balance shaft again is driven by the gears in the first pictures)


I have read that this is a know problem for the 2.0TDI from VAG. Either chain/gears are ruined, or the hex pin is rounded of.
Do the hex pin seem that bad? I can feel it wobble/spinning a little inside the balance shaft.

So to the reason I am posting this:

1. Do you guys think the hex pin and the balance shaft is the problem in my case?
2. When installing the balance shaft unit again - do i need to look at the crank/timing belt position?

Thank you so much in advance for answers, and sorry for the "bad" English!

And for the rest of you with 2.0TDI PD out there, replace this before it gets ruined to save your turbo!

[Gazwould]

Gear or chain driven twin balancer shaft oil pump module ?

[Christian96]

As you see in the first two pictures the balance shaft module is driven by gears, and not chain.

There are two shafts inside the module if I understand your question right

[DMitch16]

This is 100% the problem. The shaft in the picture has already been modified with a hexagonal insert and is no longer stock (the original hole had a spline - a 12 groove bore) into which the hexagonal key inserted. This is a weak combination. The original set up often wears out between 100000 and 160000 miles but occasionally sooner sometimes later. Unfortunately some engineers thought inserting hexagonal inserts into a rebored deeper hole then refitting with a longer 100mm key would be long lasting BUT many used inserts which were too soft and too big (the fit must be very precise) and therefore with the slight movement in the keyway and the wrong metals used, the key wore down the keyway much faster the second time. Only 2 companies I know in the UK properly re-engineer the shaft keyway to an exact fit with the key and guarantee it for the life of the car. If stain less steel inserts are used they will be too soft - if hardened steel is used it is a better match for the key but the excess movement between them still causes premature wear. The fit MUST be precise and only a thousandth of an inch or so tolerance between the key and the keyway must exist for the wear to be avoided.

In your case BOTH new parts have worn evenly together until the key started to slip in the keyway which stops the oil pump from turning - then low and no oil pressure.

Have you locked the timing? If so when the balance unit is presented to the car again the shafts must be in a certain position to align correctly with the crank gear. There is a groove on the end of the primary shaft into which an alignment plate fits. The plate is a small flat rectangular piece of metal with a small square peg in the centre of one of the flat sides. This must be inserted into the groove and rest flat against the balance unit when putting the gears together.

[Christian96]

Thank you SO MUCH for reply! First of all, the car has "only" been driven around 155.000 km. Did not know that the shaft already have been modified.
I was about to order a new reconditioned shaft from Ebay in UK (VW Passat VAG 2.0 TDI balance shaft recondition Stronger for oil pump 2005-2009 | eBay).
Do you have a site to one of the companies you recommend?

No, i did not lock the timing
Could you be so kind and give me a good summary on how to put it back on again, and what to do about that I have not locked the timing? :O

Thank you in advance again!

[Christian96]

Update:

How to install balance shaft module again (I think)

- Get the car in TDC (top dead center)
- Both shafts needs to be on the same level, then close the frame.
- Use the alignment tool on the shaft sticking out of the frame, witch has a big dent.
- When everything is lined up, bolt the module back on.

Can anyone confirm that this is the right prosedyre?
Is the alignment tool absolute necessary?
And how do i find TDC? O.o

[DMitch16]

KMB Parts Direct - The best solution in my opinion.

Home - KMB Parts Direct

You will need kit 9 and the shaft alignment plate (Ebay will do for the plate as KMB seem to be out of stock for this).

To lock the timing at TDC assuming you have removed the covers and auxiliary belt pulley bolted to the crank, you will need a crank lock and the 2 cam pins (drill bits or similar can be used as a substitute for the cam pins but I prefer the proper tools). Rotate the crank bolt clockwise until the arrow is pointing to the timing mark on the block (mine is roughly at 1 o'clock so roughly 30 degrees from vertical to the right). There are 2 types of belt however - oval teeth and round teeth. Depending on which you have will determine which of the 2 crank locks you will need. One lines up to 1 o'clock and the other 12 o'clock. So...when you have found the appropriate timing mark and aligned it with the arrow on the crank cog your crank lock should fit smoothly onto the crank cog and slot into the hole above. This could be TDC or you may be 180 degrees off as the crank to cam rotation ratio is 2:1. Next check to see if the cam pins fit into the lower slots in the cam sprockets not just a bit but all the way in (they are sometimes tight so remove the crank lock and work the crank bolt back and forth very slightly to see if the pins will slide in on both cams. If they do you should be able to refit the crank lock - it may take a small movement of the crank to do this. Once you are satisfied that the marks line up and the pins are fully inserted in the cam slots you will have TDC. If the cam pins do not fit all the way in remove all locking tools and rotate the crank a further 360 degrees until the block timing mark and crank arrow are aligned again. Retry the cam pins which should go in this time.

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Getting the unit back on is hard on your own - I have done this twice on my car as the modified shaft I had also failed in less than 50000km. It was not from KMB Direct which my new one is. The mounting bolts should be renewed. Basically with the timing locked at TDC and the alignment plate inserted correctly into the groove of protruding shaft and held there against the balance unit, you lift up the balance unit offering the top gear (intermediate of the 3) of the balance unit to the crank gear which should mesh without any difficulty. The alignment plate MUST stay in position while the gears are married together and once the unit is fully engaged and tight to the crank carrier, you then have to use a third arm to put in the first 2 bolts, which is where a second person is useful - you already know how heavy the unit is. I put in the 2 centre ones in first and tightened all the way up by hand until the unit did not move. A new circlip is needed for retaining the key in the oil pump drive hole.

Don't forget to remove the locking tools and rotate the engine manually a few times to check the gears are correctly moving. There should be a slight movement in the intermediate gear - a very small rotational play also know as backlash which is important. The intermediate gear should not be tight against the other two gears otherwise the teeth could be destroyed in a short time.

Good Luck!

[LucasAndos]

Hi probably a bit late but I just wanted to ask if this is a job someone can do on their driveway with another pair of hands. I'm close to buying a 2008 passat with a 2.0 tdi CR with the same rounded hex issue. Is it possible to just purchase the $30 replacement hex drive and continue to drive the car with it? The car already has 335,000KMs so it's not the end of the world if it fails angain soon.

[DMitch16]

Hi probably a bit late but I just wanted to ask if this is a job someone can do on their driveway with another pair of hands. I'm close to buying a 2008 passat with a 2.0 tdi CR with the same rounded hex issue. Is it possible to just purchase the $30 replacement hex drive and continue to drive the car with it? The car already has 335,000KMs so it's not the end of the world if it fails angain soon.

Firstly, a car with a failed hex drive may have already suffered significant other internal damage due to oil starvation especially if the car was not turned off quickly or was pulling significant revs at the time.
Secondly, the hex drive is not the sole issue and replacing that only is false economy. The shaft hole itself wears at a similar rate as it is not hex shaped but triple square / splined shaped (why engineers, why?!!). Also the shaft hole on earlier models was only deep enough to accept the shorter 77mm hex drive not the 100mm version another part to the overall issue. Later models may have the longer hex key, some reverting to an "improved" chain drive rather than gear drive, but with the same inadequate shaft hole design. Only by replacing the shaft (with one "re-engineered" properly with a deeper HEX hole and longer 100mm hex drive) truly solves the issue.

Depending on the shaft hole wear, changing the hex drive only may only give you a couple of thousand kms. A very worn shaft hole may not give any.

I replaced mine on my drive with a varied selection of basic hand tools (timing lock tools needed).