VW Transporter – Diagnosing causes of rattling

VW Transporter – Diagnosing causes of rattling

Vehicle: VW Transporter LT, T4

Product: Vacuum pump

Potential complaints: Rattling noises (like bearing damage on the crankshaft)

The piston vacuum pump is driven by the camshaft through a connecting tappet. In the recommended installation position, the engine oil can flow back to the engine (pictured below).

Recommended installation position

Key: 1. Camshaft; 2. Connecting tappet; 3. Tappet; 4. Piston; 5. Oil drainage; 6. Oil Collection

The installation position for the VW Transporter is as displayed (below).

Installation position VW LT and T4

If oil is not changed regularly, the engine oil ages. Oil sludge with viscous consistency builds up between the piston crown and housing. This prevents the piston from reaching its end position. There is leeway between the tappet and connecting tappet which results in tapping noises that sound like bearing damage on the crankshaft.


* Intervals for changing oil not adhered to

* Insufficient quality of engine oil

* Soot formation due to unclean combustion

* Faulty exhaust gas recirculation

Note: In case of oil sludge deposits, the vacuum pump must be replaced. It cannot be cleaned, as the vacuum pump cannot be opened with ordinary tools and there are no spare parts.

A similar complaint occurs if the wrong vacuum pump is installed with a tappet (pictured below) that is too short.

Oil sludge in the vacuum pump of the VW Transporter results in rattling noises

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