[Healeys] Fried OD Solenoid

[john harper]

Simon

The overheating is likely to because the armature has not risen enough to
break the contacts to the heavy pick coil. There is for a short while about
22 amps is flowing which heats up the heavy coil to the point where it
fails or the heavy contacts burn out. When operating correctly only the
hold current should be taken; perhaps 3 amps.  The action is that the heavy
coil is needed to raise armature until when it is at the top it breaks the
heavy current. The hold coil is sufficient to do as it says and keeps the
armature in place causing the overdrive to operate.

A frequent cause of the ODs with an open frame and with a rubber bottom
stop is that this rubber button rots with oil or falls out. With the
armature lower than it should be with the button in place the pick current
is insufficient to lift the armature with only part of it inside the coil.
the coil will then keep taking current.

On mine, I have drilled and tapped the hole in which the rubber stop was
fitted to allow a bolt and nut to be fitted that can then be adjusted as is
possible on the enclosed versions

Best regards

On Fri, 25 Mar 2022 at 15:13, Michael Salter <michaelsalter at gmail.com>
wrote:

> Bluntly Simon, the operating valve was NOT set up correctly.
> The "pull" coil was still being powered and drawing probably some 20 amps.
> New solenoid required and some careful setup.
>
> M
>
> On Fri., Mar. 25, 2022, 10:50 a.m. Simon Lachlan via Healeys, <
> healeys at autox.team.net> wrote:
>
>> Since we’re on the OD topic….
>>
>> I took my MkII BT7 out the other day, first time for ages, 8 weeks+/-.
>>
>> Anyhow, the OD didn’t work. I’d been to a carpet trimmer and left my
>> tunnel cover with him so access was easy……
>>
>> The solenoid was very hot…too hot to touch which made me suspicious.
>> Anyhow, I did my OD electrical click-test and it failed at the first
>> hurdle. So, I took the solenoid out and…well, look at the picture.
>>
>> The plastic/nylon cover to the points and wiring was virtually welded in
>> place. And the inside is a complete mess.
>>
>> So, the OD was rebuilt about 50 miles ago by OD Spares and I’m happy with
>> the wiring. My question is this…is there a frequent or a probable cause to
>> these fry ups?? These things check out at about £50:00 so I don’t want to
>> be chucking them in at regular intervals. Anything in particular that I
>> should look out for???
>>
>> Thanks,
>>
>> Simon
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