Just rebuilt my tranny. It runs great for the first 10 miles or so - shifts through all gears fine, including overdrive. Then once it gets warmed up it
stops shifting into overdrive and a bit later it starts shifting hard into 1st but
will go through the gears (except OD). Seems to be revving a bit high, too. I've adjusted the cable, too.

I'm thinking this is my overdrive solenoid, but not sure. Haven't run the codes yet - just thought I'd ask and see if anyone has had this before.

Thanks much!
Mark

 

You're saying you got 1988 AOD. If that's correct then you do not have overdrive solenoid and you cannot retrieve any codes from AOD.

Check ATF level.
Check the governor.
is the valve body bolts tight?

worse case scenario...pinched piston seal

 

Thanks, I'll check those things.

I thought there was an OD solenoid. When I called the transmission shop for
a replacement they said there were two different ones - depends on how many rings on it - so I needed to bring it in to match it. Are we thinking of a different part that we're 'calling' an OD solenoid, maybe?

The transmission is basically overheating. When it heats up I loose the overdrive, and when it starts to overheat the gears slip. I don't understand why it would overheat - I know the fluid is circulating. So it has to be something else that regulates it.

Mark

 

How do you know your trans is overheating?

Transmission do run hot. average trans temp are somehwere 170 to 210 degrees.

I assume when your trans reaches operating temperature, you loses overdrive.

My guess from where I'm sitting is::::: pinch piston seal, damage sealing rings, loose valve body bolts. [ torque the valve body bolts to case is critical]

question for you...

are you losing forward gear or just overdrive? you said " gears " [ plural] and I'm assuming more than 1 gear?

 

I pulled it apart again to get to the servos and the oil is burnt bad. I took the servo's to the best transmission place within 100 miles and they didn't think they were bad. I then brought my torque converter to them for a rebuild and they said there was nothing wrong with it. I have replaced just about every part in the thing and still can't figure it out.

When it's cool (or cold) it runs great and shifts through all gears great. It seemed at first it was revving a bit high before shifts though. Once it gets warmed up I first loose overdrive and then it starts slipping gears and starts to overheat and I loose them all. Got to the point that I had my wife tow me home 100 miles so I didn't trash it further.

I just picked up
a brand new TV cable today and will put it in and see what it does.

In the very beginning I got an error code for the oxygen sensor, but I don't think it has anything to do with this.

DISCLAIMER: My wife does the replying for me since I'm working 16 hour days so any discrepancies in these posts it's her fault!

 

nah, I won't blame your wife.

TV cable will not solved your problem. If TV cable is disconnect or borken or whatever, you will have no upshift during cold and hot trans condition.

I have to say you got internal sealing issues because you said this "It seemed at first it was revving a bit high before shifts though. Once it gets warmed up I first loose overdrive and then it starts slipping gears".
It is time for you to stop and take the trans apart and go over it carefully. You'll find damage sealing rings, missing seals or pinch seals.

Good Luck

 

(Thanks! from his wife...!!)

It's almost working now. It shifts much better (not so hard) but it's shifting too late.

I put in a new TV cable and am adjusting it with a new pressure gauge.

According to the service manual it's supposed to be set with the tranny in neutral - with the TV cable on or off it shows 80 psi. It should be between 30 - 35. No matter what I do it won't go down. I can raise it but not lower it.

What could be this problem?

 

couple thing to ask you first.

did you connect the pressure guage to correct port??
TV pressure port is on passenger side of trans case.
It is 2nd port from the rear.

if you did connect to correct TV port, then you still cannot read zero psi with the cable connect or disconnected.... you got bad valve body

you got a choice..take it apart or replace it.

if you take it apart,there few area you have to watch for is T.V valve, check ball locations and correct valve body gasket!