The Craftmans Shop > New from Old

Thwaites 2 Ton Two Cylinder Dumper Running On One Cylinder

<< < (2/29) > >>

So at least now I could manually turn the engine over, and darn me the compression 'seemed' good on both cylinders. Now I do have a petrol engine compression tester but it only goes up to 300 psi, so not a lot of good for a diesel engine.

Then I thought, if I open the exhaust valves on each cylinder in turn, crank the engine over on the starter with only one cylinder compressing, then surely measuring the current taken by the starter should give a rough comparison of the effort required and hence the compression.

The following readings are:

A/ Both cylinders decompressed (presumably least effort)

B/ Front cylinder compressing rear not

C/ Rear cylinder compressing, front not

  :scratch: :scratch: Now how odd is that  :scratch: :scratch:

It is drawing MORE current when cranking WITHOUT compressing than when the valves are closed - I can't explain that - it may be that the engine turns over faster, but it didn't seem to.

However the comparison between cylinders showed that they weren't miles off each other, but I do find those readings EXTREMELY odd  :coffee:

So I decided that probably we have an injection timing or volume issue. The pumped volume to the 'faulty' cylinder seemed less than the other, but it's a rather subjective judgement.

All the timing and volume settings are on the right hand side of the engine at a low level, with access totally blocked by the diesel tank. But before that the seat base had to come off. The air filter and hydraulic control weren't too bad, but the hand brake lever and cable were silly! The adjustment screws into a plate that was welded on under the seat mount, and without stripping the cable out all the way from the front axle (via the articulation pivot) it wouldn't rotate to unscrew. At this point I decided that it was a stupid design, and cut through the welds with an angle grinder and will re-engineer it when the time comes to put it back together. :bang:

The tank is used as a structural element supporting various horizontal bits of chequer plate so the left hand 'mudguard' (6 mm plate) and a cill plate (more 6 mm plate) had to come off before the tank fixings were accessible.

(Pictures are slightly in the wrong order)

So now at last at least I can see where all the twiddly bits are without standing on my head and using a mirror  :ddb:

There is an injector pump for each cylinder, and their 'volume racks' are linked to move in synchronism to give equal volume to each. There is a governor in the bowels of the engine that moves the racks against a spring which at rest presses the rack end against an 'overload stop'.

The setting up requires that the racks are first synchronised so that a calibration mark on each is 13/16" from the spot face on the pumps - this is set by adjusting the length of the link rod that joins them. However this setting needs to be 'at rest' when the rack is limited by the 'overload stop'

Problem is the overload stop is hideously worn and flopping all over the place


[0] Message Index

[#] Next page

[*] Previous page

Go to full version