There is no reservoir. It must be filled at the side of the overdrive unit, just like the 4-speed section. You could just loosen the fill plug, if fluid starts coming out, it's full. Otherwise, pump some more ATF in there. The plug is on the drivers side.



The trans is a 4+3, and the "+" makes it a non-searchable item. Search terms line DOUG, NASH, OVERDRIVE, are the best you can do. Or one with my name, or Scorp508, as either one of us has posted in most of the useful 4+3 threads.


The tech tips section is dead, I'm trying to revive it.

 

The tech tips section is verry useful. please do what you can

Thanks for going over this with me. I know you probably have answered theese questions before, so, thanks for your patience

If you ever need anything from me........don't hesitate to ask

 

Ok I need a ham sammich and a Pabst Blue Ribbon.

 

When the weather turns warm...and I get this OD lined out. Tell me when a SD car meet is happening and I'll gladly pay up

Otherwise let me know if you are up here on a Tuesday. Fuddruckers on El Toro has a Car meet Every Tuesday Night. You can meet the other OC Vette owners and I'll buy you a 1/2 pound Hamburger or a rib eye sammyich and refreshment of your choice.

 

Well, I got the car off the Ground and checked the fluids. The O/D Unit was full but the Tranny needed 1/2 quart.

Using my Nifty New FSM that A really great Person provided for me. We went right down the Check list of what could be wrong.

We got to the solenoid.......Hit the OD button while...

the wheels were off the ground and turning about 30mph.
The Engine Temp was 200 F.

The Overdrive light came on. The Volt meter then read 14.4v but still no overdrive. We checked the solenoid for continuity and we get....nothing. The solenoid is bad.

Is this a Dealer item? Is there a good source for these. IF so.....Who/where

Thanks again guys, this forum is great.

 

What was the ohm across the solenoid? I can't help you with replacements.

Give SK Speed a call, they might have the solenoids.

(631) 957-9427

They're in NY.

or PM Scorp508 or 5speeds, they might be of help.

 

I would like to ask a question that has bugged me since I replaced my filter and fluid in the overdrive. It was true that I could add almost 3/4 qt more after rotating the rear wheels for about a minute, but what was intended by GM?
My Shop Manual doesn't mention the rotation and automatic transmission directions clearly warn about overfilling. Does anyone have a reference for the process? I am a little concerned because it is relatively a lot more than can be added after rotation (like 50% or more) and the original level must be sufficient for the pump to work at least minimally because rotating the wheels does move the fluid to the cooler -- the pump is pumping.
Hope y'all don't mind my questionning the practices of far better mechanics than me. I just like to ask why.

 

It doesn't make sense that they would require that. They would've put the fill plug higher if that was the case.

My thoughts are... when you drain it, fluid stays in the cooler and lines and everything ahead of the pump, and this may be the rest of the capacity.

Then just a full flush would require priming. Correct me if I'm wrong.

 

Aight, I called Brian at SK. He informed me that the Solenoid will be fine. There is not going to be any ohms across the solenoid due to the pressure switch inside the case being bad...Most likely. He explained that the outside reading will be just as we found, you have to pull the pan underneath and check the solenoid that way.

He also said that all the Early units only make it 30k and that Mine With 60K is probably already been replace. I argued with him.....but decided to check the Folder after we hung up and sure as Shinola,

GM Specialist, Martinez California. 7/15/96 With 57,516 on the Odometer.......

O/H Trans, replace Clutch =$1594

So the Tranny has 9k on it since this rebuild 10 years ago.

I Doubt mechanical failure as much as "Switch" issues or Electrical Gremlens.

He did scold me ( and rightly so) for not replacing the $15 Relay. He told me that there may be some off hand issue with it and all that I've done so far may be fixed with a $15 part and a 1/2 hour of labor.

 

the only thing I question about the above mentioned service.......is.....they say:

"O/H Trans".....The four speed or the OD unit?

 

I wanted to ask you guys about the 30k mileage comment. Is that accurate?

Do the O/D units only last 30K???

 

I used to tout the overdrive unit, but mine had probably been replaced before I got to it. Half of the OD case was painted green, and the vent tube was missing from it. It was obvious someone had pulled it out, although the clutch was still original or a dealer replacement.

I was into another 85 a few weeks ago, and it had been replaced also with a different case.

Does yours still have the TV cable? (3rd cable attaching to the throttle lever?)


Anyhow, he was right to scold you for not testing the relay, it's the exact same p/n as the fuel pump relay and they can be swapped without spending a penny, but we're beyond that now. You'll need to apply pressure to the low pressure switch to check for continuity, I tested mine by hooking up compressed air to it. I forgot how much is required, maybe 30psi or so? It should say in the manual. I thought you had the pan off already.


Are you 100% positive it didn't shift into overdrive when the light came on? If the car is on jackstands, you won't even notice it engaging unless you check the speedometer.

 

My 87 has 72K on the clock and I regularly autocross the car and do track days. The OD still works fine; goes in and out of OD smoothly and the entire tranny is quiet.

The key is doing a good fluid and filter maintenance routine on the OD unit.

 

The O/D in my old 85 died at about 25,000 and the car was not abused. I pulled the unit and swapped it for a rebuilt unit at S&K.

 

They are referring to the 84-85 units which had some design flaws.

 

The Guy at SK did say the Earlier units. I took that as '84 or so.

The only reason I didn't check the relay was because it checked out per the fsm....I can learn, I'm still young, don't throw me out yet.

 

Yeah 84-85 had issues. My '87 original MK2 overdrive unit has 188k on it so far.

 

If so...what would I do with it? I mean to say, If it is on there (which I think it is) what does this mean?


No, we checked the solenoid from the outside and that is when we saw now continuity, This is where SK said we made our mistake. The Pan has to come off and the continuity of the solenoid checked from the inside or with the Pressure switched activated somehow. This Pressure that you describe with the air hose. I'll need to look into that as we stopped checking things after we get a False continuity reading from the "outside" of the solenoid.


Yea, but if that was it, wouldn't it work on the way home? Not to mention I was inside and the Speedo didn't change. Any click or movement and the two underneath complained, They were afraid it would fall on them.

We're getting there. What would happen if I just ordered the Pressure switch and popped it in here? Would there be another weak link further up the line or in the pump that would keep the solenoid from engaging?

And bottom Line. Would the bypass trick work for this situation? I mean If I had the solenoid connected to a switch that supplied 14.4 Volts to it, and all the other switches etc were bypassed...would it work?

*edit*
No the bypass trick will not fix this as it has to do with Wiring certain patches and not bypassing the switches. At least from what I could see. I'm just trying to be honest.

 

You test the solenoid by simply putting 12V to it.

It may be easier for you to jumper across the pressure switch, bypassing it, then put the car in diagnostic mode by shorting ALDL pins A and B. This will send 12V to the overdrive.

Watch the solenoid to see if it extends out.

Do not leave it powered for any length of time or you could burn the solenoid up.

I would test the pressure switch also while you're in there. It's a standard size, I was able to thread it onto common shop hose thread.

I just hate bolting stuff back together without a definitive answer, which is why you should test everything. Plus a bad pressure switch sure beats needing an overdrive rebuild.

How did the filter grommet and pickup tube look? I've seen a few that were'nt installed right and could suck air. The pickup tube and filter also have some very sharp edges that can cut the grommet on install. If the pressure switch and solenoid work, this is your last hope for a cheap fix.



The TV cable is the throttle valve cable. It was used at least on 85s, and I think on 84s. It uses the throttle lever to control overdrive shifts similar to how an automatic trans does. GM eliminated the cable around 86-87 or so and used the computer instead. The reason I asked if you have one is if someone replaced the overdrive they may have used a non-TV case, and having your TV cable missing would be an indicator.

 

^^ I didn't have a chance to do the rest of that. I am trying to get a pressure switch on the way before I pull the pan.

I DID, however, put the new relay in place and unfortunately it did not change the performance and the Woes continue.

CC, I am glad you are here. Seems if you wanna talk about Blower Packages everybody has an opinion, if you want to talk about this obscure 4x3 OD unit.....the Crickets seem to chirp. It looks like one of those deals where with your help, I have to become a 4x3 O/D expert due to the alternative being getting the dealer to put in a new one at eleventybillion dollars.