[Healeys] Fwd: Re: Overdrive non return valve Question

Roger Grace roggrace at telus.net
Mon May 25 11:44:50 MDT 2020


My thinking was that pressure may be escaping past worn accumulator piston rings and housing not allowing full pressure to build up ... ?
rg
----- Original Message -----
From: Michael Salter <michaelsalter at gmail.com>
To: Roger Grace <roggrace at telus.net>
Cc: healeylist <healeys at autox.team.net>
Sent: Mon, 25 May 2020 06:04:41 -0600 (MDT)
Subject: Re: [Healeys] Fwd: Re: Overdrive non return valve Question

Sorry but suggesting a replacement accumulator has me confused.  If the pressure is staying up as described surely the accumulator is not leaking badly ... what am I missing?M
On Mon., May 25, 2020, 12:10 a.m. Roger Grace, <roggrace at telus.net> wrote:



As you say you need need new accumulator piston/rings/sleeve and O-Rings.
This improved pressure on mine from 340 psi with very slow engaging to over 550 psi. 
Works fine now.
Suggest that you upgrade to the modern O ring style piston instead of the original metal ring style.
If you were closer could let you have the extra new spring that I have, but Can border closed.
Overdrive Spares in UK are most helpful.
Good luck ...
rg

----- Original Message -----
From: jpaynepbr at cox.net
To: gradea1 at charter.net
Cc: healeys at autox.team.net
Sent: Sun, 24 May 2020 20:21:52 -0600 (MDT)
Subject: Re: [Healeys] Overdrive non return valve Question

Shimmed the spring on the pump check valve by .08”.  Shope let me borrow an accumulator spring that was 3/64” longer. Up to over 450+ psi now.  OD will engage with the rear jacked up, but not while driving.  On jack stands, when OD is engaged, drops to +/- 410 psi then quickly comes back up to 450+. Did not change out accumulator piston/rings/sleeve or O-Rings yet, was hoping to avoid that. Thinking about trying a 1/16” washer to shim the accumulator spring or is it a lost cause?    From:gradea1 at charter.net <gradea1 at charter.net> 
Sent: Sunday, May 24, 2020 10:26 AM
To: 'jpaynepbr at cox.net' <jpaynepbr at cox.net>
Cc: 'healeys at autox.team.net' <healeys at autox.team.net>
Subject: RE: [Healeys] Overdrive non return valve Question OD Pressure should be much higher-could be 600 PSI. As I previously stated, be sure that the ball in the operating valve is the correct size- 1/4" OD in pump valve. The upper valve uses a 5/16" OD ball and you cannot mix them up, our your pressure will not be there. Too large or small a ball will not seat in the valve chamber. Also, if replacing with a new ball and spring, take a brass drift and "seat" the ball in its position. What is the condition of the piston rings and O rings...they must be up to the task as well for them to hold that huge pressure. Use sealant on all gaskets and in addition the brake ring seal to each side of the case (ignore the passage in the workshop book that says no sealant there-just be careful when applying it). Hank-----------------------------------------From: jpaynepbr at cox.net
To: healeys at autox.team.net
Cc: 
Sent: Saturday May 23 2020 5:36:24PM
Subject: [Healeys] Overdrive non return valve Question

So I pressure tested the OD at the operating valve plug – 370 PSI at 1,000 RPM in 4th.   Drops to about 340 PSI when I attempt to engage the OD. OD did not engage.This is with the back end on jack stands (not the recalled ones!), so it is under no load.Held 150 PSI for about 20 minutes after being shut off and then took about 2 hours to drop below 100 PSI.  At least I now have a better understanding of why these things leak so badly.  Who in their right mind would design something to hold that sort of residual oil pressure?Based on all the reading, pressure is too low, but nothing appears way off?I’m using the Team.Net Tech site.    http://www.team.net/www/healey/tech/big_hly/od/delborder_od.html
 Next step is to check the non return valve spring.  Question, why would I take it to a machinist to add .084” to the head of the little plunger instead of just putting a washer on the back side of the head of the plunger?  If the stem length/ insertion length into spring is that important, couldn’t I could add length to that at home with my mig welder and file it so that the spring moves freely and doesn’t hang up?  From the team.net site :psi, but for proper operation, the pressure should be at 470 to 490 psi.Now, finally... the OD low oil pressure cause and fix. A fatigued spring in the non-return valve portion of the OD (see Fig. 6.19). What? Is that it? You must be kidding - I waited two months for this? Yes, it does seem sort of anti-climactic, but this spring can cause major frustration. Springs are like people - as they age, they get shorter and weaker. As you can see in Fig. 6.19, the spring pushes against a ball and plunger. The purpose of this spring is to allow the ball to lift from its seat at each power stroke of the OD pump, allowing oil to flow into the pressurized accumulating chamber,   

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