<html><body>One other thing you could do before having to yank out the unit. Drain the oil, remove the operating valve, and the relief valve, and blow some air from the plug fitting using a rubber tipped blow gun, throughout the unit. It may make an oil mess, but not as much a mess as having to pull the transmission. This might possibly dislodge any debris blockage in the passages. If you reuse the same oil, strain it thru a good sieve and look for debris.<div><br></div><div>Then be especially careful when refilling the gearbox and OD as to not get any dirt into the opening. Be sure to check the screen and clean it with kerosene (paraffin) upon assembly. Hank<br><br><div class="reply-new-signature"></div><p>-----------------------------------------</p>From: gradea1@charter.net<br>To: "simon.lachlan@alexarevel.plus.com"<br>Cc: <br>Sent: Saturday April 16 2022 12:12:34PM<br>Subject: RE: [Healeys] Overdrive pressure not releasing.<br><br>
Hi Simon- I'm sure you read and re-read the chapter G pg. 5
paragraphs in the service manual. The fact that you have 500lbs of
pressure is good, but then the notation of the pressure not
releasing, indicates some kind of blockage in the oil passages that
will not let the pressure drain.
<div><br></div>
<div>Of course, dirt is the most common culprit. That is also why
the book suggests lintless rags...the smallest amount of debris can
plug up these tiny drillings and prevent pressure from draining.
One rebuilder I discuss these finicky ODs with, suggests enlarging
the drain hole in the operating valve body to 1mm. The other key
item to check is the two relief valve springs (ill. 16 & 56 on
plate G2). If reversed they will cause havoc with the
pressure drain. If the accumulator is stuck-not moving-it will hold
the pressure as it must move past a small drilling in the body to
release it. That is a physical issue with the O-rings, or piston
rings in that bore.</div>
<div><br></div>
<div>Actually, removing the plug from the operating valve with 500
lbs of pressure should have shot out the spring, ball and
shaft. Since it dribbled out, the blockage must be further
down the pike. Operating the lever multiple times before removing
the plug is to meant release that pressure.</div>
<div><br></div>
<div>If it has 500 lbs. of pressure, it is in OD! That pressure
pushes the two pistons (#11) toward the front of the trans
compressing the 8 clutch springs and placing the clutch facing into
contact with the sun gear.</div>
<div><br></div>
<div>Trusting that OD spares properly reassembled the unit would be
most logical, but maybe not. I think the answer is still with
them, and unfortunately you would have to bring them the unit (5th
pull!) The problem does not appear to be electrics/adjustment
related. Regards, Hank<br><br><div class="reply-new-signature"></div>
<p>-----------------------------------------</p>
From: "Simon Lachlan via Healeys"<br>
To: "Healeys"<br>
Cc:<br>
Sent: Saturday April 16 2022 10:20:09AM<br>
Subject: [Healeys] Overdrive pressure not releasing.<br><br><div class="WordSection1">
<p class="MsoNormal">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!)</p>
<ol style="margin-top:0cm;" start="1" type="1"><li class="MsoListParagraph" style="margin-left:0cm;">I’d say that
the OD has done +/- 15k miles since a total rebuild by Overdrive
Spares here in UK.</li>
<li class="MsoListParagraph" style="margin-left:0cm;">The OD had
issues before Christmas (21) and was sorted out by OD Spares. The
accumulator was uprated and pressure issues sorted.</li>
<li class="MsoListParagraph" style="margin-left:0cm;">OD functioned
100% on the few times I’d been able to take it out since then
until..</li>
<li class="MsoListParagraph" style="margin-left:0cm;">One day, the
OD stopped functioning.</li>
<li class="MsoListParagraph" style="margin-left:0cm;">I checked the
electrics. All fine there so I delved a bit deeper.</li>
<li class="MsoListParagraph" style="margin-left:0cm;">It had fried
its solenoid which I replaced. But…</li>
<li class="MsoListParagraph" style="margin-left:0cm;">That did not
fix the problem so…</li>
<li class="MsoListParagraph" style="margin-left:0cm;">I decided
that the operating valve’s adjustment might be off so..</li>
<li class="MsoListParagraph" style="margin-left:0cm;">I bought a
dial gauge and hoped to sort it out precisely rather than by
“feel”, which I lack in this area.</li>
<li class="MsoListParagraph" style="margin-left:0cm;">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.</li>
<li class="MsoListParagraph" style="margin-left:0cm;">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.</li>
<li class="MsoListParagraph" style="margin-left:0cm;">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.</li>
<li class="MsoListParagraph" style="margin-left:0cm;">AND, the
gauge stays at 500psi even when the engine is off. Moving the lever
20 times has zero effect. Stayed at 500 overnight!</li>
<li class="MsoListParagraph" style="margin-left:0cm;">Of course, I
checked for dirt in the operating valve area. None.</li>
<li class="MsoListParagraph" style="margin-left:0cm;">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?</li>
<li class="MsoListParagraph" style="margin-left:0cm;">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.</li>
<li class="MsoListParagraph" style="margin-left:0cm;">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???</li>
<li class="MsoListParagraph" style="margin-left:0cm;">Almost
finished…keep reading!</li>
</ol><p class="MsoNormal" style="margin-left:18pt;">So, I’m stumped.
Every time I learn something new about the OD, it has a new trick
to baffle me.</p>
<p class="MsoNormal" style="margin-left:18pt;">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.</p>
<p class="MsoNormal" style="margin-left:18pt;">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?</p>
<p class="MsoNormal" style="margin-left:18pt;">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?</p>
<p class="MsoNormal" style="margin-left:18pt;"> </p>
<p class="MsoNormal" style="margin-left:18pt;">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.</p>
<p class="MsoNormal" style="margin-left:18pt;"> </p>
<p class="MsoNormal" style="margin-left:18pt;">I’m hoping for a
miracle of course but some sound advice would be a godsend…………</p>
<p class="MsoNormal" style="margin-left:18pt;"> </p>
<p class="MsoNormal" style="margin-left:18pt;">Thanks,</p>
<p class="MsoNormal" style="margin-left:18pt;">Simon</p>
<p class="MsoNormal" style="margin-left:18pt;"> </p>
</div>
</div>
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