TD5 Defender
ENGINE
31
DESCRIPTION AND OPERATION
Tensioner adjuster
1. Oil supply hole
2. Tensioner adjuster body
3. Tensioner adjuster plunger
4. Sealing ring
The tensioner adjuster is hydraulically operated, oil enters the adjuster from the pressurised oil supply flowing
through the cylinder head to operate a plunger which pushes against a pivoting plastic tensioner arm. The lateral
movement in the tensioner arm causes the timing chain to tension and consequently compensation for chain
flutter and timing chain wear is automatically controlled. The adjuster is located at the front right hand side of the
cylinder head, just above the timing chain cover and below the vacuum pump oil feed port. The adjuster body is
threaded and screws into a tapping in the cylinder head. Holes are contained in the adjuster body to receive oil
from the cylinder head galleries, the oil pressure is used to force the plunger out of the adjuster body to press the
tensioner arm against the timing chain and so using the oil trapped in the adjuster body to act as a damper.
The internal damping of the hydraulic tensioner is tuned for each application. This means that pre-EU3 and EU3
components are not interchangeable.
Drive train sprockets
The camshaft sprocket has a double row of teeth which locate with the duplex timing chain. The sprocket is fitted
to the camshaft by three bolts.
The oil pump sprocket is located on the front of the oil pump housing by a single retaining bolt. The sprocket has a
single row of teeth which locates with the oil pump drive chain.
The crankshaft sprocket contains three rows of teeth, the rear row locates on the single oil pump chain and the
front two rows locate with the duplex timing chain. The crankshaft sprocket has a slot in its internal diameter which
locates with the Woodruff key on the crankshaft. The front of the crankshaft sprocket has a timing mark.
As a consequence of thicker chain links being used on EU3 vehicles, the thickness of the camshaft and crankshaft
sprocket teeth has been reduced. Individual pre-EU3 and EU3 components are therefore not interchangeable.
