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<div>Hi Paul. You are correct, I removed the low pressure valve, NOT the pump assembly. I was looking at the manual and the parts which came out appeared to be closer to those shown as the pump assembly, but neither was the same as mine. That's how I assumed it was the pump assembly.</div><div><br></div><div>So, now that I have the low pressure valve installed properly, the overdrive still does not engage. The other thing I changed was the gear oil. I always used straight 50 Wt. motor oil in my overdrives, and that worked fine. Based on a recent article in the Tech Issue of "MG Driver" magazine, I switched to EP 85/90 GL-4 gear oil. Do you think this could be causing the problem?</div><div><br></div><div>Thanks for your help.</div><div><br></div><div>Jack<br></div><div><br></div>
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On Thursday, January 17, 2019, 10:38:25 PM EST, Osborne, Paul <paul@ece.rochester.edu> wrote:
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Hi Jack, hum, a few things I might be a able to help. I have been build/repair the Laycock OD units and transmissions for a some time, for MGS and Triumphs and Jaguar. I have seen a good number. I do not claim to be the last word on these. Some info about
your unit may help. 1971 MGB is it orig to the car?
<div class="ydpe26716e7yiv7383493621">If so it should be a black label LH unit mated to a full synchro 4 Spd trans. The pump assy. Is located in the sump, not visible from the outside housing unless the sump is removed. All have a roller in the end as that is running on the input
shaft which has a pump cam. Is that what you removed? If that is not what you removed, but you removed the large nut just nest to the solenoid cover(black label) that is the pressure valve. There is not roller on that plunger. Let’s stop there for now and
let me know if this is what was removed. </div>
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<div class="ydpe26716e7yiv7383493621">Paul</div>
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<div class="ydpe26716e7yiv7383493621yqt5330100593" id="ydpe26716e7yiv7383493621yqt20554"><div class="ydpe26716e7yiv7383493621">On Jan 17, 2019, at 2:13 PM, Jack Wheeler via Mgs <<a shape="rect" class="ydpe26716e7yiv7383493621" href="mailto:mgs@autox.team.net" rel="nofollow" target="_blank">mgs@autox.team.net</a>> wrote:</div>
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Does anyone have a good exploded diagram of the overdrive unit used in a 1971 MGB, that you could send to me? I am particularly interested in the pump assembly. I changed the oil in my gearbox this week, using EP 85/90 GL-4 gear oil, as recommended in a recent
article in the MG Driver magazine.</div>
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While the car was up in the air, I noticed a leak around the plug which holds the pump assembly in place. So, I removed the pump, careful to keep all the pieces in the order in which they came out. I cleaned everything up, and reinstalled the pump assembly
and plug (part number 466-315 in the Moss catalog), with a new gasket. I thought I had all of the pieces of the pump assembly (items 62-66 in the Moss diagram) in the right order when I reinstalled it, but when I took the car out for a test drive, the overdrive
would not engage.</div>
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In addition to trying to keep the pieces in the order in which they came out, I also used the exploded diagram in the Moss catalog (Page 41) as a guide. The Moss diagram, however, is different than my overdrive unit. Moss says their diagram is for cars from
1968 to 1980, but apparently, some things were changed during that time frame. I can't believe the engineers would let anything go unchanged for 12 years! It looks like the plunger (Moss part number 466-305) shown in the Moss catalog diagram has a roller
on the end of it. My plunger does not have a roller on the end of it. Maybe this will give you a lead to which diagram I am looking for.<br class="ydpe26716e7yiv7383493621" clear="none">
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So, that leaves me looking for a good exploded diagram of the unit used in a 1971 model. Can anyone help with that, or does anyone have any suggestions as to what I might have done to make the overdrive not work, when it has always worked fine. Thanks.</div>
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Jack Wheeler<br class="ydpe26716e7yiv7383493621" clear="none">
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Paul Osborne<br class="ydpe26716e7yiv7383493621" clear="none">
Department of Electrical and Computer Engineering<br class="ydpe26716e7yiv7383493621" clear="none">
University of Rochester<br class="ydpe26716e7yiv7383493621" clear="none">
201 Hopeman Building RC<br class="ydpe26716e7yiv7383493621" clear="none">
Rochester, NY 14627<br class="ydpe26716e7yiv7383493621" clear="none">
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585-275-5226<br class="ydpe26716e7yiv7383493621" clear="none">
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