G'day everyone,
I have taken up the job of helping a friend out getting his D4 6u9366 going. It had been sitting around at a mine for about 8 years until he was told to move it so the idea was to get it going and drive it straight onto the truck. Turns out it's never that simple, we managed to start the pony motor but it always had an issue of it only firing on one cylinder and staying at low revvs. Every now and again it would rev up and fire on both cylinders and have enough grunt to spin the diesel engine but we never managed to gain fuel pressure and start the main engine. The deadline went past so the dozer was dragged onto a truck and brought into town, so we attempted to start the main engine after its arrival in town. We had the pony running and then something happened and two teeth snapped off the magneto gear and jammed up the gear train on the back of the pony motor.
The magneto rotor shaft is bent and the gear is a write off. Before the pony jammed we realised that one of the plug leads was a carbon one and that was replaced with a solid copper one and new plugs were installed just before it jammed however we still couldn't get the pony to consistently start and rev up to diesel starting RPM, it would just run like rubbish and fire on one cylinder.
Now the pony motor has been pulled off the dozer and is sitting inside and we ordered all the parts we thought we'd need. I just have one question, we received the new magneto gear and the magneto timing mark is in a different place to the old one so we are thinking that maybe the old gear was positioned wrong and that's why it wouldn't run correctly but we are unsure.
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I am just wondering which timing mark to believe.
The magneto is a American Bosch with caterpillar written on the side.
Also if anyone has a magneto for sale please let me know as we may be looking to get a new one and keep the old one as a spare.
Regards,
Alex from Tasmania, Australia.