No oil pressure on newly rebuilt CJ engine

Discussion in 'How To' started by Herman Ze Bus, Aug 28, 2020.

  1. Indeed, we want to know if the shaft was shortened, we already know it wasn't sticking out far enough. :)
  2. Gear measures 23.85mm, Shaft up to key is 33.1mm, key measures 8mm. All ish using cheapo Chinese vernier
  3. 65.25mm overall from your pic minus however far it is up the gear is the shaft length.
    It can't be worked out from your measurements, are you keeping it a secret? :)
    I guess it's 5.25mm and the shaft is 60mm
  4. 5.4mm
    docjohn and zedders like this.
  5. Excellent, agrees with my edit. Assume minor measuring error the shaft is 60mm long.
    If @Herman Ze Bus measures theirs they'll know ... something.
    docjohn likes this.
  6. As I said earlier that’s an old original VW pump, it has not been refurbished, or if it has, they used knackered parts to rebuild it. AFAIK no new parts are available for the original pump.

    I doubt if anyone has machined the shaft to make a new tang but peeps do some strange things. Put the gear in a vice and try to turn the shaft with an adjustable spanner on the tang, the shaft is not keyed and may turn if you try hard enough. I think the shaft is loose enough to push through the gear and it has eventually moved enough to disengage with the cam.

    What does the end of the cam look like and while you’re looking can you see if the drive gear is riveted or bolted?

    Was the pump difficult to remove from the crankcase? Did you have to remove the casing split line bolts above and below the pump?
  7. He’ll know that the shaft has moved through the gear.:thumbsup: The tang should engage with the slot in the cam by around 5mm, the shaft has moved by around 5mm and has fallen out of the cam.

    I can see this ending with replacing the old VW pump with a shiny new Schadek so I’ll say now that it’s not a straightforward ‘replacement is the reverse of removal’ or whatever it is that Haynes says.
    Herman Ze Bus likes this.
  8. Here’s the measurement


    Sent from my iPhone using Tapatalk
  9. EMW are apparently making pumps that fit by turning them down and sleeving but I don't see them on the website yet. Not going to be cheap.
    77 Westy likes this.
  10. I understand now thanks for your input 77 Westy,
    After putting the shaft in the vice I can’t get the gear to turn with spanner or grips. But the gear will move up and down the shaft with a quite a thud of a nylon hammer.
    I don’t have the engine in pieces anymore but do have a picture of the engine where you might just make out the camshaft - looks bolted on to me

    Sent from my iPhone using Tapatalk
  11. @zedders Sleeving is certainly better than O-rings but the OD is only one of the problems when fitting a Schedak pump. I almost asked what pump you have on the 2.4 but knowing your preference for anything original…:)
  12. Yes, bolt-on gear using button head Allen screws – clearance on those is another of the problems with the Schadek pump and the inner face of the pump may need to be machined.

    I’d get the engine builder to supply another pump; one that doesn't have a loose shaft.

    But you need to check the end of the cam. The pump shaft is harder than the cam and the slot could be damaged as the pump disengaged.
  13. Looking at the tang on the failed pump and hearing how difficult Herman found it to move the shaft one wonders whether it was moved during fitting and only ever clung on by the extreme corners.
  14. I agree, it’s likely the tang wasn’t aligned properly when the pump was installed and it pushed through the gear as the pump was bolted up. Oil pressure in the pump tends to push the shaft towards the cam but if it isn’t aligned correctly it rides out of the slot.
    EDIT: Mike mentioned this^ a couple of pages back.
    Last edited: Sep 23, 2020
    zedders likes this.
  15. I'd be tempted to push the shaft to where it should be and use it if it still felt good.
    docjohn likes this.
  16. That would be the easiest solution but I’d put a blob of weld inside the gear to stop the shaft moving.

    I’ve just re-read an earlier post, apparently there is another pump being supplied.
  17. Thats good, at least he hasn't been shafted :D:D
    Valveandy, Norris, zedders and 2 others like this.
  18. What do you think about putting a teflon button in the gap to dissuade the shaft from moving back?
  19. Insurance maybe, but if it moves laterally under oil pressure it will spin too? It seems an odd design but I guess burnt bearings might be better than chunks of steel snapping off if the pump was jammed by a foreign body.
  20. eg. the Schadek pump under the CB Maxi-3 cover has the shaft pressed out exactly 2.00mm to fit the T1 dished cam.
    To fit a T1 flat cam, a tap with a hammer was needed to adjust.
    I have done about 50k miles with the pump in dished cam configuration, pushed in the shaft at Techenders when I fitted the pump to my new engine, and done another 18k miles with the pump in flat cam.

    If it takes a hammer blow to move it, it wont move in service.

    Take a look, you may find other new pumps use the same gears.

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