Getting over my overdrive ...

[Alejandro Athie]

Hi Byron,

Following is my experience with OD's

The overdrive solenoid has to be correctly adjusted in both the upper 
position and the lower position. These adjustments may drift in time due to 
vibration, wear etc.

The lever that is on the left hand side that controls the oil valve that is 
on the right hand side should be adjusted such that it doesnt lift too much 
nor too low. a) If the lever is free to lift too much, then it might not 
open the valve enough to let a reasonable amount of oil into the cylinders 
and accumulator and the overdrive might cease to operate when the oil is 
hot, due to lower viscosity. b) If the lever isnt able to lift a minimum 
distance, then it wont allow the solenoid plunger from operating the switch 
inside the solenoid and it will burn.

At same time, if the plunger or lever are allowed to drop too much, as is 
the case when the rubber stop is missing, then the solenoid wont be able to 
pull the plunger, due to a weak magnetic field and it will burn.

I would suggest that you check all the current path wires, probably from the 
overdrive switch (wire 14 on your schematic) and wires #13 and #39 (this is 
the one that burnt), overdrive relay, throttle switch and gear box switch.

At some point in time, I had the lever adjusted too high, (to assure that 
the solenoid switch operated) and I've got some erratic operation because 
the valve can't open fully. My OD is old and it has some internal oil leaks, 
so I should assure that the oil valve opens enough. I also put slightly 
heavier oil, not gear oil, of course, but #50 instead of #30 regular engine 
oil.

As per what Doug reports, it is possible that a portion of the solenoid's 
wires are short circuited internally (insulation worn) and it doesn't have 
force enough to fully pull the plunger.

Please let me know about your progress

Alex Athie

>From: "Byron Krystad" <bkrystad@drizzle.com>
>To: <cahc@autox.team.net>
>Subject: Getting over my overdrive ...
>Date: Mon, 18 Jul 2005 08:43:01 -0700
>
>which disengaged on my BN2 at speed on hwy2 headed across Ebey Island from
>Everett toward Snohomish. Luckily, I could drop off at Snohomish and wander
>home on back roads in everything-lo. Tried the O/D switch once more to see
>if I could hear the solenoid and soon got a whiff of a Lucas smoke leak
>somewhere.
>
>I had some time Saturday to pull off the tunnel and start tracing the
>circuit but didn't have to look far. The lead between the solenoid and the
>gear switch was fried in half. Serious heat.
>
>A couple questions:
>
>1. I am assuming the solenoid failed and is at fault for overheating the
>wire. Fair assumption? What else would be at fault for that? Worn wire 
>cover
>on the lead and a sudden ground?
>
>2. I tested the gear switch and it is still at 0 ohms with third and fourth
>gear engaged, but should I be worried anyway about the shape it's in after
>being "next-in-line" for the heat that Thursday, no matter how brief?
>
>3. Any other area or aspect of the wiring I should be inspecting or testing
>in depth as a result of the incident?
>
>4. Anyone have opinions on solenoids? Lucas or aftermarket? The one I have
>says it's a Lucas but look how far that got me.
>
>5. Noticed that I don't have the rubber stop on the plunger from the
>solenoid to the O/D lever. Opinions on whether I can just live with this? I
>hope so, because I'm not sure where to hunt one down (no aftermarket part
>available).
>
>Doug Miller, I know you had overdrive issues on your BN2 coming back from
>Van Dusen, anything similar or totally different? Just curious ...
>
>Thanks,
>-Byron Krystad
>bkrystad@drizzle.com
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