Help! '85 nash OD acting stupid

[steveterry]

My OD will only engage if I start out in first and stay there until I feel it kick in ( yes, in first ). It will remain engaged thru all gears until I turn it off. It will not re-engage until I come to a complete stop then start out in first again.
Prior to this problem I had it at a Pontiac dealer for oil change. I paid and took my keys and got in, it was sitting there in Neutral. ad,:bash

Needless to say, they will not be touching it again.
Can anyone suggest what might have happened and possible direct me to a site where I can look at diagrams of this tranny and linkage set up?

Thanks
Steve.

 

[vetteoz]

I can look at diagrams of this tranny and linkage set up?

First up it is all electrical operation. ECM sends signal to relay to power up O/d solenoid.The cable is for kickdown only.

Can you disengage the O/d before driving off by pushing the button?

Doug Nash Overdrive Comparisons

 

[steveterry]

Mine has the console switch. I can turn it off and drive with only 4 forward but this is not good for hwy driving.
Do you see any issues arising from the Pontiac "Mechanic" pulling the trans out of reverse?
Steve

 

[vetteoz]

Do you see any issues arising from the Pontiac "Mechanic" pulling the trans out of reverse?

No, that is only a cable link from the shifter to key to make sure car is in reverse before key removed.Not connected to trans. Just trying to sort your problem out.
Switch will turn O/d off , but not on?

By default O/d is on when you start the car , you have to manually disengage it by pushing the button.
As you have O/d from a stop; that means the ECM is sending signal to relay to operate O/d so wiring / relay / solenoid are fine.

 

[steveterry]

Yes, when the toggle switch is in the "on" position I have OD from first gear (from a standing start) but no OD if I switch it on after I'm out of first.
If I leave the switch in the "off" position I do not have OD at all.
BTW- Whenever I do Have OD switched on AND engaged the dash indicator light lights up.
Do you think that I should remove the + battery ( clearing the computer)?
The OD connection on the Trans was unpluged at one point but is now connected.
Steve

 

[larry bud]

Sounds like a sticking valve in the valve body of the OD, IMO. You should not have OD in first gear.

Drop the OD oil pan (get a new filter while you're at it.). Then remove the OD valve body and clean it. Back when I had the 4+3 I've had small pieces of the gasket come off and jam in the valves. The valves are spring loaded, and a pin holds them in place.

IIRC correctly, there are two.

Don't forget a new gasket as well, and new oil.

 

[steveterry]

I took it out again today to try to narrow things down.
The problem now seems very eratic. No rhyme or reason to it.
Sometimes it will engage in first, sometimes not but mostly will not engage at all.
I'll try the valve body cleaning and new oil if I can ever find a place that will let me use their lift / pit.
Steve

 

[vetteoz]

BTW- Whenever I do Have OD switched on AND engaged the dash indicator light lights up.

That shows that the ECM is at least trying to operate O/d so that part is working correctly.
At this point ,I don't think it is a internal problem
I think it is more a control problem ; bad or faulty relay / bad connections on the relay (very common, insulation shrinks back allowing shorts ) / etc.
You could also check that the O/d has the right amount of fluid in it; too low will cause problems