Repairing oil pump drives for 2.0 PD TDIs with balance shafts. (Articles)

In all 2.0 TDI pump-injector engines with balance shaft module, the oil pump is driven by a 6-point shaft that is insufficiently sized.

In case of failure, the worn hexagon will no longer drive the pump, and serious consequences can occur if one does not react quickly.

FAQ:
- How do you notice the damage? Not at all, unless it's already too late: An error message appears on the instrument panel indicating a lack of oil pressure.
- Is there a way to find out if my 2.0 TDI is affected? All 2.0 TDI engines from the Volkswagen Group with pump-nozzle injection and balance shafts, and some early Common Rail TDIs, where the oil pump is driven in these cases always via the undersized 6-point. Engines without the balance shaft module or later Common Rail TDIs are, to my knowledge, not affected. The company Wild has created a list of engines with problems on the balance shaft module. TDI models from 11/2009 are no longer affected.
- What should you do in case of an error? IMMEDIATELY use the next safe stopping possibility and stop the engine. The lack of lubrication on the engine and turbocharger leads to very rapid and severe damage (= total loss), unfortunately, the oil pressure monitoring system is also slow, meaning it does not immediately indicate the lack of oil pressure under all conditions.
- What can be done proactively if you own the affected vehicle? Replacing and upgrading the 6-point oil pump is usually a manageable task (apparently not in the A6 4F models, unfortunately), which involves removing the oil pan. As a precaution, a new 6-point pump should be installed. As a guideline for checking, I estimate around 1500 operating hours to be reasonable. If the balancing wave is already heavily worn, it must also be removed, repaired, or replaced.

Damage Assessment:
- The turbocharger is particularly vulnerable due to the lack of engine oil supply. By removing the suction snorkel, it is possible to check the turbine shaft for whether it is already "stuck" or exhibits excessive play.
- By removing the camshaft cover, the camshafts can be inspected for wear and tear on the valve tracks. If the camshafts show signs of wear, this is unfortunately very bad, as the bearing surfaces on the crankshaft will then hardly look any better. In this case, a complete engine replacement would be a good option.

Before the repair, reading the error codes from the engine control unit with VCDS is advisable. If there are problems with the charging pressure regulation or the PD elements, it is sensible to address them.

Expansion and Repair of the Balance Shaft:
To disassemble the oil pan on the A6 4F, the engine mount must be loosened and the engine raised a good distance. After removing the oil pan, the positions of the balance shafts, the intermediate gear, and the crankshaft are initially marked. The subsequent installation must definitely take place in the same positions, otherwise the compensating waves will become unbalanced waves!
Do not remove the intermediate gear for the balancing shaft module. Reason: The "adjustment" of the gear clearance is achieved through a wear coating and a new gear; otherwise, it is difficult to adjust correctly. The tooth flank clearance is 0.038mm to 0.072mm.
The oil pan is not completely easy to remove despite the raised engine: From outside the car, turn to the right to see the rear side and simultaneously tilt the oil pan forward to remove it. Remove the connector from the air conditioning compressor. It makes sense to practice this process before re-installation.
The re-installation of the oil pan was carried out using Loctite SI5926 as the sealant. The two mounting screws of the oil pan in the clutch bell housing were "glued" into the openings with sealant, as it is difficult to insert them once the oil pan is in place. For these two screws, a hexagonal head with a ball joint and the correct length (approximately 12cm) is required.


Torque of the screws:
- M6 Schrauben, Ölpan: 15Nm
- Large screws for horizontal connection of oil pan - Gearbox: 45Nm
- Large screws, vertical connection, oil pan - Engine block: 40Nm
- M7 Screw Balancing Wave Module: 13Nm and rotate 90° further
- M8 Schrauben, Ausgleichswellenmodul: 20Nm and 90° further turn