The timing case of the Y 25 DT engine comprises two parts.
The upper part is integrally cast on the cylinder head, the lower part is bolted to the cylinder block and the engine oil pan as an additional housing part.
The crankshaft rotational movement is imparted to the camshaft via the chain drive.
Three chains are used in the Y 25 DT engine:
- Oil pump drive chain
- High-pressure pump drive chain
- Camshaft timing chain.
The high-pressure pump drive chain and the timing chain are tensioned via a hydraulic chain tensioner which acts on these two chains via two chain tension rails.
- The chain tensioner is a double-acting tensioner. In one housing, two pistons each act on one tension rail.
- Sealing of the timing case to the crankcase with beaded sheet-metal gasket.
Illustration L0008371 shows the position and the components of the engine timing side of the Y 25 DT engine.
| 1 | Outlet side camshaft sprocket | 8 | Oil pump drive chain |
|---|---|---|---|
| 2 | Sliding rail for camshaft timing chain | 9 | Timing chain drive gear |
| 3 | Inlet side camshaft sprocket | 10 | High-pressure pump drive chain |
| 4 | Guide rail for camshaft timing chain | 11 | Tension rail for high-pressure pump drive chain |
| 5 | High-pressure pump drive gear | 12 | Hydraulic chain tensioner |
| 6 | Sliding rail for high-pressure pump drive chain | 13 | Timing chain tension rail |
| 7 | Oil pump drive gear | 14 | Camshaft timing chain |
Illustration L0008375 shows the chain tensioner which simultaneously tensions two chains via one tension rail each.
- 1. Hydraulic chain tensioner
- 2. Tensioning piston for camshaft timing chain
- 3. Tensioning piston for high-pressure pump drive chain