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Overdrive over pressure continuation

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mgann Mike Gann
West Point, UT, USA   USA
The "Overdrive cover bulging" topic is buried so far I thought I had better start a new one.
I am frustrated. Those who have been following will know I experience and "over pressure event" that deformed the solenoid cover. I rebuilt and cleaned the solenoid components and control valve checking that the assembly was correct and in the proper order. It was suggested that I get a oil pressure gauge to check the operating pressure of the system. It came in today and I joyfully installed it and began testing. Started with no washers to get a baseline pressure. In 3rd gear flipped the switch and pressure came up to about 75psi and then continued on up to 340psi. So I put 2 washers in and repeated. That brought the pressure up to about 375, just short of the minimum 380. So I figured each washer was about 17.5psi. 2 more washers would bring me up to 410psi, 15 short of the maximum 425. Problem is when I flipped the OD switch the pressure did not come up. I checked the electrical and it is all good. I took the 3rd and 4th washers out and no go. I took the valve out and cleaned the valve and the socket. No go. The only thing I have left to do is replace the solenoid, but it was working fine on the first 2 tests. Is there anything I am missing? I guess a new solenoid at $160 is in order. Frustrated as hell.

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dickmoritz Avatar
dickmoritz Platinum Member Dick Moritz
Philly 'burbs, PA, USA   USA
Mike,

It's not clear to me. You say you saw operating pressures of 340 and 375, but then you say that the next time you tried the overdrive there was no pressure after adding several more shims. Is that correct?

Dick



Errabundi Saepe, Semper Certi
(Often wrong, but always certain)

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mgann Mike Gann
West Point, UT, USA   USA
Yes. When I activated the overdrive switch nothing was happening. It was like the solenoid was not operating. I have since pulled the solenoid and checked for continuity and it checked good, but the thin copper contact piece came off the coil. So I have ordered a new coil. I was going to attempt to solder the copper thin washer back onto the hair thin wire, but I figure I would rather have a new one.
The plunger in the bronze or copper sleeve may have been stuck in the sleeve. It moves smoothly in the sleeve, but catches when it is at the bottom. In the position in the first picture it moves smoothly, but when it gets to the bottom position like in the 2nd picture it stops or catches. Is this a problem and could be what is stopping activating the OD?

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mgann Mike Gann
West Point, UT, USA   USA
I might as well send a picture of the coil and contact washer too.


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jimb Avatar
jimb Jim Brown
San Francisco Bay Area, USA   USA
1967 MG MGB
Isn't that washer supposed to be soldered to the coil wire?

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dickmoritz Avatar
dickmoritz Platinum Member Dick Moritz
Philly 'burbs, PA, USA   USA
Mike,

Ordinarily the solenoid plunger does not travel that far down, but I would certainly take a minute with a little 220 or 320 to "clearance" the I.D. of the brass/bronze tube. Cheap insurance. While you're waiting for a new solenoid coil, you could surely solder the tiny wire back onto that end plate. Note that the two ears on the end plate abut either the top or bottom plate of the solenoid coil, so you might polish the mating surfaces with a Scotchbrite pad to assure electrical continuity. It is through these two ears that the solenoid circuit is completed to earth.

I'd think an hour's work or so would have your overdrive working nicely again...

Dick




In reply to # 3909558 by mgann Yes. When I activated the overdrive switch nothing was happening. It was like the solenoid was not operating. I have since pulled the solenoid and checked for continuity and it checked good, but the thin copper contact piece came off the coil. So I have ordered a new coil. I was going to attempt to solder the copper thin washer back onto the hair thin wire, but I figure I would rather have a new one.
The plunger in the bronze or copper sleeve may have been stuck in the sleeve. It moves smoothly in the sleeve, but catches when it is at the bottom. In the position in the first picture it moves smoothly, but when it gets to the bottom position like in the 2nd picture it stops or catches. Is this a problem and could be what is stopping activating the OD?



Errabundi Saepe, Semper Certi
(Often wrong, but always certain)

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29desoto Avatar
29desoto Gold Member Wayne Sanders
Outside Otis, OR - in the woods!, USA   USA
1965 MG MGB V6 Conversion "Carmine"
1968 MG MGB GT "New Yeller"
1973 MG MGB GT "Eliza - FIRST PLACE - MG2013"
1984 Chevrolet Corvette "The Green Weenie"    & more
Dick, as usual, is right on the money. I'd mention tho that the new solenoids come with a much better grounding system.

And for fifty bucks, it can be yours.



Wayne Sanders
Rose Lodge, OR
(TD 4288)

"I don't care to belong to any club that accepts people like me"-joined Willamette Valley Club in 2011

73 MGB-GT virtually stole this one. Someone up there likes me.

68 MGB-GT the daily mule. Solid as a rock, but rattles like a can full of them!

79/65 MGB - Carmine- V-6 - T-5
This car is now very nearly completely done. Sure to find something else, but not now.........

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mgann Mike Gann
West Point, UT, USA   USA
I ordered the new solenoid last night or actually this morning about 2:00a. Not that I am worried or anything. Sometimes I just don't sleep. I also stayed up to solder the contact washer back on. I am a proficient solderer. Used to work on Weapon Systems for the USAF and have had High Reliability Soldering training. Was able to tin the tiny wire on the coil so made a good connection to the contact washer. Now I will massage the end of the brass tube to ensure the piston does not get caught/hung up in the end. Then back together for some testing. When the new solenoid comes in I will replace my repair job. It looks like it might be an original part. It has cloth insulation on the wire and paper over the coil. Maybe time to replace it anyway. This car needs to be reliable as I drive it, or at least I was, everyday. Thanks all.

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mgann Mike Gann
West Point, UT, USA   USA
Ok, so just finished the test drive. Worked perfectly. Halelujah, let us rejoice!!
I believe the problem of intermittent operation was the small crumple zone on the bottom of the brass tube. It probably occurred during the over pressure event (which I will probably never know why it happened). The piston was catching on that area and the overdrive would not work.
By the way, Oil pressure with 4 washers is just what I calculated at 410psi. It hesitates when activated just a little longer (maybe 1 sec) to shift into overdrive.
On the road again. Now you know the rest of the story.
Thanks again everybody. Thanks for hanging in there with me. Gotta keep these babies moving.

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dickmoritz Avatar
dickmoritz Platinum Member Dick Moritz
Philly 'burbs, PA, USA   USA
Ok, so just finished the test drive. Worked perfectly. Halelujah, let us rejoice!!

Hot diggity overdrive !!! smileys with beer

Dick



In reply to # 3909773 by mgann Ok, so just finished the test drive. Worked perfectly. Halelujah, let us rejoice!!
I believe the problem of intermittent operation was the small crumple zone on the bottom of the brass tube. It probably occurred during the over pressure event (which I will probably never know why it happened). The piston was catching on that area and the overdrive would not work.
By the way, Oil pressure with 4 washers is just what I calculated at 410psi. It hesitates when activated just a little longer (maybe 1 sec) to shift into overdrive.
On the road again. Now you know the rest of the story.
Thanks again everybody. Thanks for hanging in there with me. Gotta keep these babies moving.



Errabundi Saepe, Semper Certi
(Often wrong, but always certain)

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