88 Auto trans question HELP!!!!!!!!!!!!

[markfagus]

Hi guys. I recently picked up an 88 with the 3.0 auto trans.
Engine was rebuilt less than 1000 miles ago and runs strong. The issue is the trans wont go into OD. All other shifts are fine but no matter what your speed is after engine fully warmed up, OD will not engage. Coolant system has been checked and is fine, trans solenoids and relays all also checked out fine.
The truck did sit for a while (>18 months) when the engine was being rebuilt but the previous owner drained all the fluid before it was parked. The fluid that is in it is less than a month old and was added after the engine rebuild was done.

Any ideas what the issue is? Am I looking at having to rebuild the trans? I would appreciate any help you guys can offer.

thanks

Mark

 

[Bad_Vision]

tranny sat without fluid = very BAD
moisture will build up and rust happens chances are that tranny needs a rebuild now.

If the solenoids are good then your left with the valve body and that's never cheap.

Option 1: rebuild
Option 2: Drive it until whatever seized is un-seized. try lucas tranny additive or some "transmission honey".

I would say if the rest of the gears work fine that the overdrive solenoid is the issue.

 

[markfagus]

I guess the good thing is that I am in the desert in New Mexico so moisture and rust is not an issue most of the time. I am running some additive in there now to see if that does the trick. I have only driven 150 miles with the additive in it. How many miles would it take to un-seize if that is going to work?
Is there a separate solenoid just for overdrive? Does replacing the OD soleniod require dropping the trans?
Any idea how much replacing that will set me back? or a guess on the cost to rebuild?

 

[Bad_Vision]

from what i gather you only need to drop the transmission oil pan to replace the OD selinoid
the transmission shift selinoid runs about 120$ and you might as well spen the extra 20$ to do the filter while your in there seeings how you will need a new gasket after removing the oil pan.
under 200 all said and done if you do it yourself

 

[AddictedOffroad]

It could also be a bad coolant temp switch for the tranny. These trannies will not allow you to shift into OD until the engine temp hits a certain temp. So, if that switch is unplugged or bad, it wouldn't allow it to shift into OD.

Scotty