I can be driving for 10 mins or an hour and until I drive over 45-55 miles an hour, my tranny won't shift into overdrive. Once I get to driving 45-55 miles an hour for appx 10mins, it finally shifts and then I'm good for the day. I went to a tranny shop and they suggest cleaning out my anti-freeze and swapping out the thermostat. It definitely has nothing to do with being cold or hot cause my top radiator tube is running hot and my thermostat gauge is working fine. Plus I'm still filled to the top in my radiator. So does anyone have any suggestions? I think it might be a sensor or tranny adjustment. Thank you for replying!!!! I have a 2nd gen loud six.

 

I don't know what flushing the cooling system and replacing the thermostat would do for you as far as your tranny goes. The tranny fluid only runs in the bottom of the radiator. (On a side note, the thermostat doesn't control your temp. gauge; it just adjusts the flow of coolant depending on the temperature of the engine. If you wanted to replace it, its only about $8 and 45 mins.) I think most 3.0 autos take some time to get warmed up before they will shift into overdrive. I know mine takes about 5-10 minutes of going 55 before it will upshift into OD. Longer if its cold. Someone else will chime in, but this seems pretty normal...

 

Ok so I just re-read your post. Musta missed the part where it said you could be driving for an hour. Now that IS odd. Mine won't shift into OD until I hit about 35, but 45-55 seems a little high. Is this something it has just started doing, or has it always done it?

 

I picked up this 2nd gen in august and found it always like this. The previous owner hardly drove it and was not aware of this. Thank you for helping me out!

 

Toyota tranny's will not shift into overdrive until the engine reaches a certain temperature. There is another thread with this exact same problem. Do a search and you will find it.

 

thank you for your info...i'll try more searches...what you guys are saying is making more sense in how my tranny is reacting...just trying to figure out why it could take an hour before the temperature is reached.

 

an hour is a long time for it to take to shift. the transmission wont shift into o/d until it is warmed up, common in th autos and a bit disconcerting until you know what it is or is not doing! if you have a transmission cooler, it is possible that it would take longer to warm up and shift into o/d.

one benefit, you know which mechanic not to take your rig to.

lee

 

very funny! I'm finding mixed info as far as the temperature is to blame and possible sensor issues or coolant clogged flow...I will have to swap out parts to confirm my issue....