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Thread: canopy problem

  1. #1
    Senior Member wizrod's Avatar
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    canopy problem

    Hi all...its been a while...but I finally have some time to pop my head round the door & to devote to my Nova...

    I'm getting it ready for a fresh MOT and to enjoy through the remainder of the Summer.

    One of the jobs I wish to address is to fix an annoying behaviour of the roof mechanism.

    It is set up as has been discussed elsewhere with a pair of double throw switches (internal & external). Push the switch one way and the up valve & the motor are activated - roof goes up! Push the switch the other way and the down valve & the motor are activated - roof goes down! All well and good. Also, the roof stays where its put - so the down valve holds pressure.

    However, while the down valve holds pressure, to stop the roof falling, the other valve doesn't. The upshot is that if I release the up switch part way up, since the pump motor takes a second or so to stop (due to its rotaoional momentum) it continues to pump the roof up - may be an inch or less.

    The problem is that the same occurs when I release the down switch when closing the canopy. If I release the down switch as the canopy fully closes, as the motor winds down, roof is pumped back up again...I can never get a positive seal, so the roof rattles as I drive along....

    I've re-checked the external side of the control circuit and all the relays are operating as they should.

    I therefore wonder if there could be a problem with one of the valves in the pump (a Smiths Mini-Pack). I'm wondering if the up valve is not working at all and is stuck(?) open...?

    Any thoughts...suggestions....insights....guesses would be gratefully recieved!

    cheers

    Paul
    cheers

    Paul

  2. #2
    Take all hydraulic pressure of the rams and see if it settles down and seals.
    It maybe being sprung up by something other than hydraulics.

  3. #3
    ***Euro-Nova Supporter*** Spacenut's Avatar
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    Hi Paul - does your canopy system have limit switches fitted, or can you just run the pump as long as the switch is depressed (in whichever direction)?

    Reason I ask is, if you don't have limit switches, try running the pump for a few seconds after the canopy closes, to force the canopy down and compress the seals. If the solenoid valve in the Smiths pump has failed it should be fairly obvious as the canopy will not be held down under hydraulic pressure after you release the switch.

    If you do have limit switches, which switch off the pump automatically when the canopy is open or closed, there could be an adjustment issue. The limit switches are set up so that they reverse the direction of the pump at the end of the cycle, so that the pump direction is ready to go when you next press the switch. So you might have a situation where the canopy gets to the bottom of the close cycle, the limit switches trip, but the canopy isn't completely closed and starts the open cycle on the overrun.

    My canopy used to rattle incessantly when I had the Cadillac pump (no negative holding pressure), so I remember how annoying it can be. Hope you find the culprit soon!

    Lauren
    only Pythagoras can save me now!

  4. #4
    Quote Originally Posted by wizrod View Post

    I therefore wonder if there could be a problem with one of the valves in the pump (a Smiths Mini-Pack). I'm wondering if the up valve is not working at all and is stuck(?) open...?

    l
    The smiths mini pack uses two little valves pushed by springs if memory serves me correctly. My old smiths pump had an issue with the valve stuck in the closed position, luckily my neighbor was a hydraulics specialist. He stripped the pump and turned two new little valves out of titanium which he had going spare.

    I still have two smiths minipack pumps going spare that I plan to sell at some point if you are interested.

  5. #5
    Senior Member wizrod's Avatar
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    Hi Lauren, Gmacz, David,

    Many thanks for your replies.

    There are no limit switches....the motor continues run as long as I hold the switch down, though I'm careful not to let it run once the roof is fully open or closed.

    There are no springs involved....it's just the rams acting on a set of rather nice stainless hinges as supplied to the Club by one of the members some years back.

    I've been pondering the problem, having reviewed the section on serviceing the mini-pack in the Nova modification manual, and I agree with you, David, about the valves. I think that the valve that should control the flow of the fluid from/to the top of the rams is stuck open. Since the valve is 'normally closed' and needs an electric impulse to open, I guess that the valve itself is either stuck open the return spring has broken or the rubber seal inside the valve has failed and is passing fluid even with the valve closed.

    I think my plan will be to see if I can get a local hydraulics company to service & fix the pump or else try to sourse a replacement, to which end I'd be very interested in buying one of your spare mini-packs, David, should you wish to sell.

    This may also be an opportune time to service/replace the rams and hoses and perhaps move the pump from the engine bay to a spot up front, as where it is mounted now would be the best spot for the external oil filter.

    Thanks again

    Cheers

    Paul
    cheers

    Paul

  6. #6
    Paul,

    As you may know I live in Singapore, but my current plan is that I will be back in the UK for a short holiday at the end of September. So if you want one of the pumps PM me and we can discuss logistics / pricing if that timescale works for you.

    Regards

    David

  7. #7
    Senior Member wizrod's Avatar
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    Cheers David. I'll send you a PM.
    cheers

    Paul

  8. #8
    ***Euro-Nova Supporter***
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    You mentioned that the motor overruns by ~1 second,
    so I am wondering if the relay that powers the Smiths mini-pack motor is sticking on.
    So the mini-pack valves switch on/off *before* the motor (or while the motor is still operating).


    You may well have an old-school Mini starter motor solenoid as the relay for the Smiths motor.
    Google "lucas 4ST starter motor solenoid mini"


    I believe that if the Solenoid is slow to release (sticky) you would get the symptoms you describe.
    I'd recommend replacing the Solenoid before pulling the mini-pack to pieces.

  9. #9
    ***Euro-Nova Supporter*** Spacenut's Avatar
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    That's a good point - especially if a normal automotive relay has been used instead of a starter solenoid, and can't handle the current (upwards of 30A)

    Ford solenoids were also common.
    only Pythagoras can save me now!

  10. #10
    Senior Member wizrod's Avatar
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    I think you have misunderstood me. When I said the motor runs on briefly, I meant that once the power to the motor is shut off, it doesn't stop dead, but takes a short time to wind down due to the momentum of the rotating parts in the motor.

    Power to the motor is controlled by a Lucas starter relay, which in turn is controlled by a pair of standard 30A automotive relays - one each for Up & Down, plus a 30A relay each for the 2 valves in the pump. I've tested each individually & they all work fine.

    TBH, I've had this problem issue since I've had the car - (& I've renewed all the electrical controls since then). In fact, I once had to squeeze out of the car by pushing the roof up by hand - I could never have done this if it was held down under pressure, so I think its a fair bet that the pump is where the problem lies...

    P.
    cheers

    Paul

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