D Type O/D Problems

[thebrookster]

Posted on behalf of a friend, who is having some issues with his overdrive. His car is a MGB I'm afraid, however we understand the O/D is the same, hence posting here.

Basically, when he clicks in his OD he gets a click from the relay, and a single click from the solenoid, but no action other than that.

Firstly, any advice in what could be causing this? All my OD's have a) worked and b) been J-type, so I am kinda stuck before we start :)

Secondly, upon advice he has measured the amperage used by the solenoid, which is reading 0.18A. Now according to a website we found the D Type should use 17A initially as the "pull in" current, then drop down to 2A to hold the solenoid in position. Is this correct, and would this indicate that the solenoid is buggered?

Cheers for all advice,

Phil (and Jon)

P.S We have tried to convince him to get a Triumph, but he seems rather enamoured with the MGB sadly  :o :o :o

[Richard B]

Take the sideplate off and when the solenoid is engaged the small hole in the arm should line up with a datum hole in the casing (1/8" drill bit IIRC), There is an adjustment on the plunger to set this correctly.

Yes you can check the current with an ammeter.

Make sure the oil level in the gearbox - O/D is correct. Also there are filters to clean.

[heraldcoupe]

thebrookster wrote:

Posted on behalf of a friend, who is having some issues with his overdrive. His car is a MGB I'm afraid, however we understand the O/D is the same, hence posting here.

Assuming this is a pre-1968 MGB to have the D-type overdrive.
From 1968 the MGBs had an LH overdrive, which is different to anything fitted to a Triumph,  I believe (could be wrong) that all those with D-types had the 3-synchro gearbox. The 4-synchro box came with the introduction of the LH.

Cheers,
Bill.

[thebrookster]

Richard, current has been checked, was reading 0.18A. Do you happen to know if this is correct, I was thinking it sounded like a new solenoid could be called for, but I did not want to give a definite answer to prevent him having to spend more then needed.

Bill, sorry, we know it is a D type OD, my comment was more aimed at the gathered info that that this OD is the same as the Triumph OD. The car in question is a 67 MGB GT :)

Cheers,

Phil

[Richard B]

Sounds low, I would check with the plate off.

Engine not running but ignition on, see if the solenoid moves the arm. and do the alignment test with the drill.

Unless access in the MG is so poor you can't?  :-/

[piman]

Hello Phil,

that current draw is very low, first thing to check is connections including the earth, it could be as simple as a high resistance connection?

Alec

[Pete Lewis]

the drop in current is controlled by the travel of the solenoid plunger, set the lever as Richard says, there is a simple switch in the end of the solenoid which changes over the coils when touched by the plunger,
some are sort or accessible most are sealed in the solenoid end and are not serviceable.

remove the solenoid and check the plunger core  is not corroded and is a easy movement ,
in operation it does not move very far,  

current is generally 10 amp to pull in and 0.5amp once holding.

make sure the  control relay and inhibitor switch are working OK  no dodgy connections .

if you are checking filters inside the square cover on the n/s pull out the plastic magnetic rings these tap a load of nasty metalic residue.

Pete

[thebrookster]

Latest Update on this:

Quote:

Hi

Update

I managed to remove the solenoid, the plunger stays attached to the overdrive doesn't it ( i hope) i then connected 12v to the wire from the car battery, and earthed the solenoid cover, the piston in the solenoid didn't move at all, all that happened was the solenoid got hot very quickly and oil fizzed from the terminal end.

Does this mean its had it, and i may have found the problem at last? But why did it click on the car?

Thanks

Cheers for all the advice so far, hopefully get this sorted soonish :)

Phil