[Healeys] Overdrive pressure not releasing.

Roger Grace roggrace at telus.net
Mon Apr 18 09:03:29 MDT 2022 

To confirm Michae's analysis, consider:
  remove ball, spring and plunger
  remove the valve push rod and inspect - I use a piece of steel wire of
appropriate thickness to pry out.
  replace the push rod - it should go in smoothly
  insert the wire again and push down gently; with your other hand operate
the cam and you should feel the operating rod move up and down on the cam.
 if not MS is correct and the pin/peg has failed....
 of course it could also be the cotter pin that goes through the setting
lever - but less likely IMO
BTW I have found that my OD (O rings) holds 400 psi for several days.
rg



<http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail>
Virus-free.
www.avg.com
<http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail>
<#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>

On Sun, Apr 17, 2022 at 3:21 PM Simon Lachlan via Healeys <
healeys at autox.team.net> wrote:

> That’s the one I’ve got. I did get an increase in pressure. No question
> about that.
>
> I talked to Dave at OD Spares with regard to the various accumulators out
> there at the moment. I don’t recall exactly but he supplies all of them to
> his customers and, I think, to the suppliers.
>
> Simon
>
>
>
> *From:* Healeys <healeys-bounces at autox.team.net> *On Behalf Of *Bob
> Spidell
> *Sent:* 17 April 2022 23:06
> *To:* Michael Salter <michaelsalter at gmail.com>
> *Cc:* healeys at autox.team.net
> *Subject:* Re: [Healeys] Overdrive pressure not releasing.
>
>
>
> AH Spares has an accumulator and piston which uses an O-ring. It appears
> the pressure relief hole is chamfered:
>
>
> https://www.ahspares.co.uk/austin-healey/performance-parts/gearbox-overdrive/o-ring-conversion-accumulator-piston.aspx
>
> On 4/17/2022 12:03 PM, Michael Salter wrote:
>
> Actually Bob I've never used an  "O" ringed accumulator.
>
> I spent a little time many years back looking into using "O" rings on the
> accumulator but couldn't resolve the issue of the ring being chaffed when
> passing over the radial drillings in the accumulator body.
>
> Does anyone know how that has been solved?
>
>
>
> M
>
>
>
> On Sun., Apr. 17, 2022, 2:49 p.m. Bob Spidell, <bspidell at comcast.net>
> wrote:
>
> Michael,
>
> Sounds like you're implying the O-ringed accumulator is superior to the
> metal ring (OEM) type? Wish I'd known about it when I rebuilt my O/D (I
> bought the DWM 'uprated' accumulator).
>
> I'll throw out another, very unlikely, potential cause: the cone clutch
> could be stuck together. I've heard of this happening, but have never
> experienced it my self--nor has anyone I know--but it's theoretically
> possible (esp. if the clutch is excessively worn). Could this be the reason
> the manual is adamant about replacing the 8 strong springs, of two lengths,
> that oppose the operating pistons on overhaul, regardless if they still
> seem robust?
>
> On 4/17/2022 9:31 AM, Michael Salter via Healeys wrote:
>
> Simon,
>
> Based upon your synopsis I conclude that the operating valve is NOT
> opening when either the solenoid lever or the setting lever is being moved
> to the position where the operating valve ball would normally be lifted off
> its seat.
>
> This conclusion is based upon your discovery that the pressure in the
> accumulator, as indicated on the gauge, does not leak away overnight.
>
> There is a small clearance between the operating valve push rod and the
> overdrive housing. If the operating valve ball was indeed lifted off its
> seat all the oil in the accumulator would, over time, leak past the
> operating rod thus discharge the accumulator.
>
> This process would indeed take some time but would certainly completely
> relieve most, if not all the residual accumulator pressure overnight.
>
> If however the operating valve ball is still in contact with its seat
> (i.e. not being lifted) the oil pressure would not reach the small
> clearance between the valve push rod and the housing and, other than past
> the accumulator rings there is nowhere for that pressure to be relieved.
>
> I would presume that Overdrive Spares installed an accumulator with an "O"
> ring rather than the original cast iron rings. If the original type
> accumulator piston was still fitted, oil would seep past the cast iron
> rings to relieve the pressure, albeit very slowly, and again the
> accumulator pressure would be discharged overnight..
>
> The cam on the operating shaft, the one which lifts the operating valve
> push rod and thus the operating valve ball, is locked to the shaft with a
> small taper pin. I would guess that the taper pin has either fallen out or
> sheared.
>
> Bad news is that this pin cannot be accessed without removing and
> disassembling the overdrive.
>
>
>
> M
>
>
>
> On Sat, Apr 16, 2022 at 1:19 PM Simon Lachlan via Healeys <
> healeys at autox.team.net> wrote:
>
> My OD is driving me mad and I definitely need some inspired advice. A bit
> of background first. I’ll try to lay out all the facts in a logical
> sequence. (I’m increasingly reluctant to link ODs with logic!)
>
>    1. I’d say that the OD has done +/- 15k miles since a total rebuild by
>    Overdrive Spares here in UK.
>    2. The OD had issues before Christmas (21) and was sorted out by OD
>    Spares. The accumulator was uprated and pressure issues sorted.
>    3. OD functioned 100% on the few times I’d been able to take it out
>    since then until..
>    4. One day, the OD stopped functioning.
>    5. I checked the electrics. All fine there so I delved a bit deeper.
>    6. It had fried its solenoid which I replaced. But…
>    7. That did not fix the problem so…
>    8. I decided that the operating valve’s adjustment might be off so..
>    9. I bought a dial gauge and hoped to sort it out precisely rather
>    than by “feel”, which I lack in this area.
>    10. Prior to using the gauge I decided to see if the OD was
>    functioning at all so I raised the car on stands and fitted my pressure
>    gauge.
>    11. I get a reading of 500psi rising a bit when I rev the engine but
>    I’d suppose that would drop when the oil warms up.
>    12. BUT, and this is where things go pear-shaped…moving the little
>    lever on the RHS up and down does not engage/disengage OD. There is no
>    change on the gauge to show OD engaging or disengaging.
>    13. AND, the gauge stays at 500psi even when the engine is off. Moving
>    the lever 20 times has zero effect. Stayed at 500 overnight!
>    14. Of course, I checked for dirt in the operating valve area. None.
>    15. Likewise, the tiny hole in the “valve – operating” (the spindle
>    thing which the ball sits on)….that’s clear. And surely, the pressure would
>    diminish overnight if something in that area was partially obstructed?
>    16. When I remove the pressure valve, there’s a small spillage – no
>    more than you’d expect – but repeating the pressure gauge process only
>    returns the same results.
>    17. I see in the bible according to Norman Nock that “Holding this
>    lever with your thumb and index finger, you should be able to push the
>    lever down lightly about ⅜” until you feel a slight spring pressure
>    resistance. The lever should go down another ¼” after encountering the
>    resistance……” ie there’s about ⅝” movement up & down in that lever. Well,
>    my lever does move and does lift the ball, but there’s not ⅝” movement
>    there. Could that be the problem area???
>    18. Almost finished…keep reading!
>
> So, I’m stumped. Every time I learn something new about the OD, it has a
> new trick to baffle me.
>
> I’ve no 100% sure way of telling whether it’s gone into OD  and stuck
> there or whether it’s simply not going into OD at all.
>
> I’ve done a lot of reading through my books and collection of advice from
> the various gurus and found reference to ODs being stuck but those seemed
> to be to do with “weak springs” which, particularly after a long lay-off,
> wouldn’t disengage. The cure for this being a good smack on the steel plate
> sandwiched in the OD from below. Well, that seems to be a stuck mechanism
> issue whereas I’m facing a hydraulic conundrum. Or am I?
>
> There is what is usually referred to as the “pressure relief valve”
> adjacent to the accumulator. The name suggested that pressure might be
> stuck in that area….but surely not overnight?
>
>
>
> Any ideas? I am particularly reluctant to take the gearbox and OD out.
> You’ll recall the ridiculous business of the defective clutch kit? Well, I
> forget whether we had the box in and out 3 times or 4. I’d hoped not to do
> it again so soon or ever for that matter.
>
>
>
> I’m hoping for a miracle of course but some sound advice would be a
> godsend…………
>
>
>
> Thanks,
>
> Simon
>
>
>
> _______________________________________________
> Support Team.Net http://www.team.net/donate.html
> Suggested annual donation  $12.75
>
> Archive: http://www.team.net/pipermail/healeys
> http://autox.team.net/archive/healeys
>
> Healeys at autox.team.net
> http://autox.team.net/mailman/listinfo/healeys
>
> Unsubscribe/Manage:
> http://autox.team.net/mailman/options/healeys/michaelsalter@gmail.com
> <http://autox.team.net/mailman/options/healeys/michaelsalter@gmailcom>
>
>
>
> _______________________________________________
>
> Support Team.Net http://www.team.net/donate.html
>
> Suggested annual donation  $12.75
>
>
>
> Archive: http://www.team.net/pipermail/healeys http://autox.team.net/archive/healeys
>
>
>
> Healeys at autox.team.net
>
> http://autox.team.net/mailman/listinfo/healeys
>
>
>
> Unsubscribe/Manage: http://autox.team.net/mailman/options/healeys/bspidell@comcast.net
>
>
>
>
>
> _______________________________________________
> Support Team.Net http://www.team.net/donate.html
> Suggested annual donation  $12.75
>
> Archive: http://www.team.net/pipermail/healeys
> http://autox.team.net/archive/healeys
>
> Healeys at autox.team.net
> http://autox.team.net/mailman/listinfo/healeys
>
> Unsubscribe/Manage:
> http://autox.team.net/mailman/options/healeys/michaelsalter@gmail.com
> <http://autox.team.net/mailman/options/healeys/michaelsalter@gmailcom>
>
>
> _______________________________________________
> Support Team.Net http://www.team.net/donate.html
> Suggested annual donation  $12.75
>
> Archive: http://www.team.net/pipermail/healeys
> http://autox.team.net/archive/healeys
>
> Healeys at autox.team.net
> http://autox.team.net/mailman/listinfo/healeys
>
> Unsubscribe/Manage:
> http://autox.team.net/mailman/options/healeys/roggrace@telus.net
>
>
<http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail>
Virus-free.
www.avg.com
<http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail>
<#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://autox.team.net/pipermail/healeys/attachments/20220418/084d3714/attachment.htm>

More information about the Healeys mailing list