OVERVIEW
Genuine VW/Audi turbocharger oil return line bolt, part number N-905-927-03. This original fastener retains the oil return line at its specified attachment position on the confirmed ALH arrangement below. One bolt is supplied.
Technical details
- Original number: N-905-927-03 / N90592703.
- Published nominal size: M6 x 16.
- Flanged external hex head, as pictured.
- Application: specified turbocharger oil return line fastening position.
- Return line, gasket, sealing components and other hardware are separate.
The oil return line carries oil away from the turbocharger toward the engine sump. Its mounting hardware retains the prescribed line connection while the specified sealing components contain the oil. Correct line positioning and fastener selection are necessary for the designed attachment.
This fastener is separate from the oil feed-line fittings and other turbo mounting bolts. Nearby connections can require different hardware. Match the exact return line position and original number before ordering, especially where the line arrangement has been updated or modified.
Common reasons to replace
Inspect the fastener during turbocharger removal, oil return line replacement or service of a disturbed return-line seal. Replace missing hardware, stripped threads, rounded head surfaces, deformation or corrosion that prevents correct installation. Renew removed hardware whenever the factory procedure requires it.
Previous turbo or oil-line repairs can leave an incorrect fastener length or a damaged bolt. Check the attachment and mating threads before assembly. A bolt that bottoms before the connection seats cannot establish the intended mounting condition.
Oil leakage at the return-line area requires diagnosis of the line, seals, connection and surrounding engine components. A new bolt cannot repair a cracked or restricted line, failed gasket, damaged mounting flange or stripped mating threads. Correct the diagnosed cause before reassembly.
Installation and service notes
Follow the factory turbocharger oil return line procedure for the ALH engine and the actual fitted line arrangement. Allow the engine and turbocharger to cool, control oil drainage as directed and keep contamination out of opened oil connections.
Identify the assigned fastener position before removing the line. Inspect the line, mating flange or bracket, sealing surfaces and threaded mounting point. Obtain the specified sealing components and remaining hardware separately.
Position the return line without forcing it against surrounding components. Start the assigned bolt by hand in undamaged threads. Do not use the fastener to pull a misaligned line into place or compensate for a damaged flange or incorrectly seated seal.
Use the correctly sized tool fully engaged on the head. Follow the factory tightening sequence, thread preparation and renewal requirements for this oil-line connection. Do not transfer a generic M6 torque value or a specification from another turbocharger attachment.
Where an updated or aftermarket return line is fitted, confirm the verified installation instructions and hardware requirements for that exact component. The original bolt number does not establish compatibility with every modified oil-line arrangement.
Restore the engine oil level as prescribed after the repair and complete the required operating and leak checks. Confirm the return line is correctly secured and clear of surrounding components before returning the vehicle to service.
Fitment
| Vehicle | Model years | Engine | Configuration | Application restrictions |
|---|---|---|---|---|
| Volkswagen Jetta | 1999–2003 | 1.9L turbocharged direct-injection diesel, ALH only | Mk4 sedan, front-wheel drive; Original factory arrangement | Mk4/A4 chassis only; excludes Mk3 Jetta and other TDI engine codes. Specified turbocharger oil return line bolt position requiring N90592703. Match actual return-line arrangement. One bolt supplied. |
Confirm Mk4 chassis, ALH engine and original N90592703 at the oil return line attachment. One bolt supplied.