[Healeys] Overdrive pressure

gradea1 at charter.net gradea1 at charter.net
Tue Aug 3 11:21:38 MDT 2021


Simon-glad you found the problem. That little valve is the whole
control of the pressure and release and dirt is the main offender. 
What I see on my gauge is pressure over 400-450, then when OD is off.
a steady bleed down to 300, 200, 100 then in a couple of minutes, or
sometimes a bit longer, goes to 0. Its a "slow bleed". Fades as the
oil flows down thru the valve and that tiny hole. Enlarging it will
make the bleed faster and the plugging up with debris harder to
achieve. They recommend a 1MM hole if I remember the readings
correctly, but its a small drilling to allow oil to pass smoothly to
the sump. This is why you don't want 90W gear oil-its to "thick" to
work with the unit, and it also foams up in the annulus. Good 30W (or
20-50) NON detergent oil is best to keep this process working.
(detergents also foam)
Possibly a little oxidation or crud gets between the ball and the
seat, and it then needs a smack to reseat the fit. Small thing matter
in this scenario. We all need a smack, now and then, to get with the
program. Regards, Hank

	-----------------------------------------From: "Simon Lachlan via
Healeys" 
To: "Healeys"
Cc: 
Sent: Monday August 2 2021 1:24:09PM
Subject: [Healeys] Overdrive pressure

	David, Hank…..thank you for help and advice. Hank you were just
about on the money. 

	You’ll recall that my OD was slipping in & out at low revs? Of
course you do. 

	I bought a gauge from ODSpares, excellent people/very helpful. (In
retrospect, I wonder how I’ve managed for so long without one). 

	Pressure showed as well into the 470 to 490 range whilst OD was
engaged at +/- 1,500 rpm in 4th. Which is GOOD. 

	But, pressure dropped to zero immediately upon disengaging and
switching off. Which is BAD. 

	The little hole in the so-called “Valve operating” was/is clear. 

	I phoned Dave Twigger at ODSpares who said that there was debris
under the ball on the seat there OR, if it was clear, then the ball
needed reseating. 

	So, I gave the ball a few brisk taps and the pressure drop did slow a
little up on the next gauge test. 

	I gave it some more taps and it improved somewhat again. Now takes
about 30 seconds to get down to, say, 20psi and then loses pressure
quite slowly. 

	So:- 

	* How hard can one “Tap” the ball? Not the easiest question to
answer, I do appreciate that. One man’s tap is another man’s
wallop?

	I suspect I’ll have to repeat the process…… 

	* What time duration is acceptable in operating terms for the
pressure drop? What am I aiming at?

	Thanks, Simon
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