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Recently I've been seeing increasing numbers of failures with the Ambac M-50 Injection pump plunger guides.
This is attributed to the lower quality LSD fuel available over the last few years.
The reason for this post is to alert 002 / 003 owners to a slightly different failure mode on these plunger guides that I've seen recently.
For years I've seen broken plunger guides that split in half, as a safety mechanism to prevent damage to the pump.
I'm no metallurgist, but I'd assume they were made of a specific hardness steel that would resist deformation, but rather split cleanly, separating the plunger from the drive gear.
Recently I've seen probably 5 or 6 IP's where the plunger guide didn't split open, but rather the hardened plunger skipped 90* or 180* within the plunger guide, while deforming the corners of hole in the guide.
Possibly this is due to a change in the manufacturing process and / or the manufacturer itself of the GU8546 plunger guide?
The result is a generator that may start and run but will probably not produce full rated power. The valve cover will get excessively hot fairly quickly and the air louvers may open abnormally fast due to the excess heat.
The other problem is that if you continue to run the machine with the injection timing way off, the excess heat will overheat the injectors fairly quickly, causing the needles and nozzles to seize up.
So if your 002/003 sits for an extended period of time and upon starting you notice:
Slower starting / excessive cranking before it begins to try to start
Decreased power
Excessive heat
decreased RPM even at W.O.T
Check your pump timing to see if the plunger guide has skipped.
I would assume that rather than immediately removing and tearing into the IP, checking the IP timing using the flow method described in the TM should tell you right away if there is an issue deeper inside the pump.
This is attributed to the lower quality LSD fuel available over the last few years.
The reason for this post is to alert 002 / 003 owners to a slightly different failure mode on these plunger guides that I've seen recently.
For years I've seen broken plunger guides that split in half, as a safety mechanism to prevent damage to the pump.
I'm no metallurgist, but I'd assume they were made of a specific hardness steel that would resist deformation, but rather split cleanly, separating the plunger from the drive gear.
Recently I've seen probably 5 or 6 IP's where the plunger guide didn't split open, but rather the hardened plunger skipped 90* or 180* within the plunger guide, while deforming the corners of hole in the guide.
Possibly this is due to a change in the manufacturing process and / or the manufacturer itself of the GU8546 plunger guide?
The result is a generator that may start and run but will probably not produce full rated power. The valve cover will get excessively hot fairly quickly and the air louvers may open abnormally fast due to the excess heat.
The other problem is that if you continue to run the machine with the injection timing way off, the excess heat will overheat the injectors fairly quickly, causing the needles and nozzles to seize up.
So if your 002/003 sits for an extended period of time and upon starting you notice:
Slower starting / excessive cranking before it begins to try to start
Decreased power
Excessive heat
decreased RPM even at W.O.T
Check your pump timing to see if the plunger guide has skipped.
I would assume that rather than immediately removing and tearing into the IP, checking the IP timing using the flow method described in the TM should tell you right away if there is an issue deeper inside the pump.
