I have been meaning to do this for ages. What I want to do is illustrate what you will find inside the engine, what's most likely to be the cause of a leak and what might also happen in rare cases. Here goes:
Overall
There are three areas where you may find internal diesel leaks:
Behind the fuel pump door
Under the rocker covers
The low pressure fuel pump
These pictures are of an SR2, the arrangements are much the same on the rest of the S range and in the H range too
Fuel pumps:
Here we have the two fuel pumps. Running across the middle of the picture is the fuel feed pipe, a copper one in this engine. Coming out of the pumps and running up inside the fuel pump housing are the delivery pipes
Rocker covers:
The injector is in the centre here, held down by the beam with the stud at each end. The injector pipe is coming up from the pump between the push rods. The spill rail is on the far side, comes out of the injector, loops under the beam and out the side of the engine under the rocker cover joint
To try to make things clearer, this is the fuel system with the engine removed (?!)
Pumps at the bottom linked by the feed pipe, injectors at the top of the injector pipes and the spill rail. There are no prizes for pointing out what is wrong with this set up
Feed Pipe
The feed pipe connects to the fuel pump with a banjo bolt
There is a seal each side, in this case they are Dowty washers, older installations may have copper washers
Common problems:
Loose banjo bolts, Damaged sealing washers. Either of these will show up as leaks around the washers. As a first step, check the banjo bolt is tight
Uncommon problems. Broken fuel pipe.
The pumps are held down by a Y shaped clamp with a central bolt:
If this bolt is loose, the pumps can move around which can cause fatigue cracking of the pipe. On engines with a lift pump, operating the priming lever may show fuel squirting out of cracked pipes
Bleed point
Each pump has it's own bleed point, used for bleeding air out of the pump body
There's a copper sealing washer that seals the screw to the body
Common problems:
Loose bleed screw, damaged sealing washer. As a first step, check the bleed screw is tight
Delivery valve housing
On top of the pump are two hexagonal parts. The upper one is the nut on the end of the injector pipe. The lower is the hexagon that is used to tighten the deliver valve housing into the pump.
The correct way to undo or tighten the injector pipe is to put a spanner onto each of these hexagons and squeeze. This doesn't always happen, and it is possible to loosen the delivery valve housing, which will cause a leak.
To check this, with two spanners, slacken the nut on the injector pipe. Then tighten the delivery valve housing into the pump, finally with two spanners retighten the injector pipe
A loose delivery valve housing will cause erratic running, and also leaks when the engine is not running
Injector pipe
Again, a loose injector pipe will give poor running as well as leaks when the engine isn't running. If the delivery valve is working OK, this is much less likely, so leaks here, at the delivery valve housing and at the injector are much less likely. You're going to notice a cylinder not working more than a leak. Having said that, three cylinder Listers do seem to run OK on two cylinders
The injector pipe connections at the pump and the injector are metal to metal seals:
As long as the connections are tight, they should be fine. A damaged nipple on the pipe will cause poor running
Richard