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RE: Overdrive on 77 MGB

To: "doug russell" <dr-doug@classic.msn.com>
Subject: RE: Overdrive on 77 MGB
From: Tom McLaughlin <tomm@ti.com>
Date: Mon, 08 Sep 1997 13:25:25 -0500
Well...I struggled with the overdrive this weekend with some success, but
ultimate failure so far.  I checked the switch, and it was not closing so I
fixed that.  The overdrive then would engage, but would disengage once I
stepped on the gas.  It had not been engaged for 6 months so I thought this
was not so strange.  After doing this a few times, the overdrive went in
fine and stayed in.  The switch and overdrive worked fine for that
half-hour drive and another.  On Sunday, I drove it again it became harder
and harder to get the overdrive to engage and last night it would not go in
at all.  I checked the switch several times and it is working fine now.  I
checked the oil and it is full.

I went to check the electrical connection to the solenoid, but did not want
to cut the wire (It is insulated all the way into the solenoid.  I cannot
find the correct wire under the hood.

My plan was to drain the transmission oil next weekend, clean the filter
and see if the solenoid is getting 12v.  Is there any way to test the
solenoid?  Once out of the casing, the other side is not grounded.....

By the way, this is my first MG (really my first project car) so I am still
learning where all the pieces parts are......any help would be greatly
appreciated!

Any thoughts???  I am hoping that it is not the pump as Doug suggests it
could be below...

================

At 01:17 PM 9/5/97 UT, doug russell wrote:
>1. Unlikely that it is the switch but check it to rule this out.  To check
the 
>switch, engage the overdrive switch while the ignition is turned on.  Under 
>the hood to the upper left side of the engine compartment you should be able 
>to find a yellow wire that goes from the main wiring harness to the 
>transmission tunnel (if you cannot find a yellow wire check a wiring diagram 
>to determine which is the correct wire from switch to OD solenoid).  With
the 
>switch on, this wire should be hot and, of course, not hot when the switch
is 
>off.
>2. After ruling out the switch, make sure you have a good electrical 
>connection to the solenoid (that's the same wire but check it right before
it 
>goes to the solenoid in the OD unit).
>3. If it's not electrical then check to make sure your tranny has the proper 
>amount of oil as low oil could cause the symptoms you describe - however,
this 
>is also unlikely.
>4. Well, if it's not electrical and it's not low oil, it's probably the pump 
>and I'm still working on getting mine fixed.
>
>Hey, I've been there.
>
>
>Dr. Doug 
>A gathering of 69 MGs in my garage experimenting with some new chemical 
>compounds. 
>-----Original Message-----
>From:  owner-mgs@autox.team.net  On Behalf Of Tom McLaughlin
>Sent:  Thursday, September 04, 1997 5:49 PM
>To:    mgs@autox.team.net
>Subject:       Overdrive on 77 MGB
>
>All,
>
>I am new to the list and very greatful it exists so thanks in advance.
>
>The overdrive in my 77 B used to work, but would not always engage.  I
>would have to throw the switch several times.  It now does not engage at
>all.  I believe the switch is just worn, but thought I would see if anyone
>else had this problem so I could cut down my troubleshooting time.  What is
>the best way to start to troubleshoot this???
>
>Any thoughts???
>
>Tom
>
>
>
>

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