[Healeys] Overdrive pressure not releasing.

gradea1 at charter.net gradea1 at charter.net
Sun Apr 17 10:49:50 MDT 2022 

MICHAEL-GOOD ASSESSMENT OF THE ISSUE! THAT PRESSURE HAS TO FIND A PATH
TO BLEED DOWN...SLOWLY. IN MY SYNOPSIS, I FOOLISHLY ONLY MENTIONED THE
TWO RELIEF SPRINGS AS CULPRITS...I MEANT TO SAY BALLS & springs, On
the early OD, and many of the later ones, the two relief balls are
different sizes- one is 1/4" and the other is 5/16" Somewhere, I wrote
which is which...(think the oil pump is 5/16 not 1/4") will have to
locate info. BUT, if they are reversed the valve balls will not
function correctly. One way causes it to leak-no pressure, and the
other way it could be jammed and not releasing.
Simon's lever has limited travel-jammed? A friend had no pressure
after assembling his unit-reversed the balls and it then worked
perfect-400lbs and proper operation. Hank

	-----------------------------------------From: "Michael Salter via
Healeys" 
To: "Simon Lachlan"
Cc: "Healeys"
Sent: Sunday April 17 2022 9:32:36AM
Subject: Re: [Healeys] Overdrive pressure not releasing.

  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  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!) 

	* I’d say that the OD has done +/- 15k miles since a total rebuild
by Overdrive Spares here in UK.
 	* The OD had issues before Christmas (21) and was sorted out by OD
Spares. The accumulator was uprated and pressure issues sorted.
 	* OD functioned 100% on the few times I’d been able to take it out
since then until..
 	* One day, the OD stopped functioning.
 	* I checked the electrics. All fine there so I delved a bit deeper.
 	* It had fried its solenoid which I replaced. But…
 	* That did not fix the problem so…
 	* I decided that the operating valve’s adjustment might be off
so..
 	* I bought a dial gauge and hoped to sort it out precisely rather
than by “feel”, which I lack in this area.
 	* 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.
 	* 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.
 	* 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.
 	* AND, the gauge stays at 500psi even when the engine is off. Moving
the lever 20 times has zero effect. Stayed at 500 overnight!
 	* Of course, I checked for dirt in the operating valve area. None.
 	* 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?
 	* 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.
 	* 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???
 	* 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 

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