4He Pump Rebuild

	Drain oil
	Gasket on drain plug is a little damaged
	Oil case removed
	Old gasket (yellow) and internal oil mist filter (gray). About to replace both.
	Old filter is very greasy
	New gasket (left), old gasket (right) for oil case
	Old filter removed
	Remove outlet piece. O-ring is completely destroyed. About to replace it.
	Old o-ring, new o-ring on pump outlet piece.
	Old and new gaskets for fill plug. Looks like a history of tightening these plugs too much and deforming the gaskets. Rubber gaskets/o-rings shouldn't be overtightened.
	Old and new gaskets for second plug.
	Remove sight gauge. There's a green gasket between the glass and the outer piece, and an o-ring between the glass and the case (this is the gas seal).
	New gasket and o-ring for sight glass. Round o-ring fits in oval slot, kinda odd. Needed to make sure it was seated properly.
	Not sure what this H-shaped piece is but there's a replacement so I'm replacing it. It's thin, flexible metal.
	Brand new internal oil-mist filter.
	New oil case gasket.
	Motor removed.
	Manual says to loosen set screw and pull coupling/fan blade off shaft. But it doesn't just come off. Need a puller. CSE shop had one but the size was wrong. Built a piece in the shop to screw onto the coupling with a threaded center hole for the puller bolt.
	Slow process with wrench and screwdriver for leverage, pull coupling off shaft millimeter by millimeter.
	Finally off. (How do you get it back on? Guess I'll find out.)

	New and old motor gasked
	Old (left) and new coupling elements. Old one is a little squareish in the middle but seems undamaged. Change it anyway.
	Center screw and washer removed from pump shaft
	Coupling removed from pump shaft. I was able to lift it off by hand.
	Centering disk screws removed… to remove the disk use these extra push holes, then can kind of tilt it off.
	Centering disk removed. Pump guts exposed.
	Old shaft seal in centering desk, new shaft seal on the right. No obvious damage to the old one.
	Difficult to remove old shaft seal - completely destroyed it in the process.
	New and old bushings. Haven't figured out how to pull off the old one yet. Theoretically there's an o-ring underneath so it should probably be replaced.
	New gasket on motor and fan+coupling replaced. This took some work. The inner diameter of the aluminum coupling got scratched up when I removed it, I guess from scraping on the upper edge of the shaft. Spent a while on the lathe with sandpaper on a rod to smooth it a bit. After that it slid on fairly easily.
	Old and new o-rings which sit below the centering disk. Old one did not seem damaged but we'll replace it anyway.

	Removed inlet module.
	Notice there's a plate, and actually two o-rings. Replace both o-rings, though neither looks damaged.
	Pulled out this little rod with a black rubber hat. This is the anti-suckback valve. There's a replacement hat so we'll swap that out too, though old one looks OK.
	Bottom sides of old and new hats, and hatless rod. Hot pops onto the little ball at the end.
	Remove oil case again in order to remove the pump module.
	Took a slight amount of prying to remove pump module. New gasket in yellow, old one is dark brown.
	Old gasket is a different, stiffer material and came off in pieces.
	Old gasket removed completely.
	Finally got the bushing off! Starting with a screwdriver and some gentle tapping with a mallet, then a little more prying with screwdrivers and a pry tool borrowed from the shop.
	The o-ring to be replaced is in a recess on the shaft; it compresses against the ID of the bushing.
	New bushing (right) is a somewhat different design.
	Removing old o-ring. Was able to do so without breaking it.

	New gasket on pump module
	Remove ring clamp, under disk is a gasket/washer. Replacement washer on lower right.
	Remove rod and spring. At the bottom is a plastic gasket of some sort.
	Removed old gasket (on screwdriver), new one above.
	Replace pieces.
	Ready to reinstall pump module.
	Pump module reinstalled. Used lead brick to gauge the correct torque (7.5 Nm)
	Replace internal oil mist filter.
	Ready to insert new shaft seal
	New shaft seal inserted
	New shaft seal inserted, bottom view
	Ready to install centering disk with new shaft seal. But it doesn't fit. The pump module is slightly off-center.
	Remove pump module again (after first removing oil case again) to attach centering disk.
	Reinstall pump module. With the centering disk attached you can get the centering right.
	Coupling reinstalled.
	Reassembled pump, and all the pieces that were replaced (except for one more gasket, see below).

	Two remaining panels to look at.
	Upper port is for an optional external oil filter. Lower is for the gas ballast - there's a fitting to connect an external inert gas supply.
	Oil filter cap has a gasket, and there is a replacement.
	Old gasket removed (center), new gasket to right of old gasket. Far right is a gasket of a different design, maybe you use that if you have an oil filter (but that middle strip is not relevant if you just have the cap). I replaced that gasket and reattached both caps.
	Here are the pieces in the rebuild kit that I couldn't find in the pump.
	Refill 4He pump with oil, Leybonol 100 LVO
	Oil at about 35%. Note that the oil makes the ridges in the glass invisible. Previously I thought that there was a ridge glass or plastic piece floating on the oil.

	Pump opened up

	Inner casing
	Pump system attached to safety valve housing
	Screws connecting pump system to safety valve housing removed
	Removed screws holding down pump system and safety valve housing
	Compression spring removed
	Pump system detached from safety valve housing
	Valve flap in pump system broken

2019 April 12