Rover's Vikingship Overhaul of the 2400 SD
Diesel engine part four
Rover's Vikingship


This part of site is an attempt to organize and add to the web resources for the Rover SD1 to form a cohesive and easily usable guide for those of us without easy access to expert repair and/or advice. It is not offered in any way as a definitive source and we take no responsibility for any errors that may exist.
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Cylinder Head Overhaul

The next components we will look at are the cylinder heads. As the two service procedures you will come across form part of the cylinder head replacement procedure, we will consider a situation where the cylinder heads on an engine require attention.

For photographic purposes, we will look at the operations on an engine mounted on a stand. All the operations we are about to describe can be carried out in the car.

As you might expect, it is possible to remove individual cylinder heads. However, if you are removing one of the inner assemblies, No. 3 for instance, you will need to remove the adjacent cylinder head, in this case No. 4 first. Similarly if you wished to remove No. 2 cylinder head, then you would have to remove No. 1 head first.

So the cylinder heads can be removed in either of 3 combinations, a single head assembly, a pair or all four.
As we shall see later in the section, this means that there are 3 possible torque tightening sequences.

The cylinder heads should only be removed when the engine is cold. Before a cylinder head can be removed it will be necessary to remove the appropriate injector pipes, inlet manifold, exhaust manifold, water manifold and oil feed pipe.

You will notice that the exhaust manifold comprises two parts joined together by piston ring type seals. If leakage occurs between the manifolds, then replace the seals making sure that the gaps are diametrically opposite each other.

Before you release the retaining bolts, mark each head to identify its position on the engine.
Once you have removed the cylinder heads you can dismantle them, clean and overhaul them as you would on any other engine.

A maximum of 0.2mm (0.008 in) can be removed from the face of a cylinder head to restore it.
The minimum permissible thickness of the heads is 89.95 to 90.05mm (3.541 - 3.545 in).

If you do have to machine a cylinder head then machine all four cylinder heads and end plates equally to ensure satisfactory alignment of the manifolds on reassembly.

Valve guides are replaced using tool 18G 1377. But first you must heat the head uniformly to 80C - 90C. Drive the old guides outwards from the combustion chamber and the new ones in towards the combustion chamber.

Valve seats should be restored to data in the Repair Operation Manual using the appropriate tools.
If necessary valve seats which cannot be restored, can be replaced as can the prechambers. The procedure for doing this is described in the Repair Operation Manual.

The rocker assemblies need little explanation. During overhaul inspect all the components making sure that there is no obstruction in the oil passages. If you remove the pedestal stud then coat the lower threads with an approved locking compound before refitting it into the head.
Similarly during reassembly coat the underside of the pedestal securing nut with Molyguard before tightening it to 11 kgf.m. (80 Ibf.ft.).

Gasket Selection

Now for reassembly. There are two thicknesses of gasket to achieve correct piston clearance. The thicker one, shown here on the left is identifiable by the extra small hole at the top which does not align with any apertures in the block or head.

To determine which gasket is required, set the No. 1. piston at TDC. Clamp a dial gauge to the top face of the cylinder block. Position the indicator tip on the liner external rim.

Take another reading this time with the indicator tip on the piston crown. The difference between the two readings determines which gasket should be used. If a thin gasket is to be used then check the other three cylinders.

Again make sure that you use the same gasket for all four cylinder heads. In the case of individual head removal and refitting you would use a gasket of the same thickness as the one you removed.

Torque Tightening Sequences

The cylinder head can then be replaced and torque tightened using the appropriate sequence.
Here we see the sequence to be used when you have removed only one of the heads.

You would use this sequence if you were replacing two heads and this sequence if changing all four heads.
Before tightening the cylinder heads, loosely assemble the inlet manifold and the water manifold to align the cylinder heads. Insert the small bolts first to align the gaskets then torque tighten the bolts in the appropriate sequence.

Once you have refitted the cylinder heads, you can refit the manifolds with their gaskets. But before you do this check the alignment of the faces, to make sure that the manifold will seat correctly without straining them.

Finally check and set the tappet clearances. The inlet valves should be adjusted to 0.30mm (0.012 in), the exhaust to 0.45mm (0.018 in).

Diesel engine part one
Diesel engine part two
Diesel engine part three
Diesel engine part five

Torque Wrench Setttings of the Diesel engine



© rwp jan 2005