Hello everyone and thank you for admitting me!

I cannot find the cause for the symptoms that the blazer has transmission wise, and we would be grateful for your help.

The blazer was working fine for the first 6 months we had her until it was driven on non stop 3 hour drive at night from LA to Bakersfield California.

After we exited the freeway we came to a complete stop and when the light turned green the transmission would only work in 3 and 4.

Reverse 1 and 2 gears we're inactive. The blazer struggled off the line but shifted normally from 3 to 4 when sufficient road speed was attained.

We parked in a hotel parking lot and called it a night.

The next morning the blazer worked fine in reverse 1 and 2 but now 3 and 4 we're gone. Manually shifting does not change anything.

We have not attempted any repairs or diagnosis since the Bakersfield trip in January of this year. In it's current transmission trim it will comfortably achieve and maintain 45 MPH. There are no leaks or noise and it shifts fine other than 3 and 4 are still missing in action.

Where would be a good place to start diagnosing the issue? Thank you very much.

 

Dont know much about transmissions myself, it maybe you got a wire hot and touched somewhere on the three hour trip... give it time someone will chime in...

 

Thanks for the reply DonL. I think you are on the right track.

 

Welcome to the forum! What were the fluid level and condition at the time of issues? I can't come up with a scenario to have those conditions appear. How do you get it to start out while you only have 3-4?
Brad

 

It moved slowly Transman. The next day R12 we're working.

I'm going to pull the pan and the solenoids and rods and look for debris, would that be a good place to start?

 

You have to remember this is a 26 year old unit. Probably has been gone through at some point in its life. You didn’t mention the mileage. So you could drop the pan and take a look, but I would suspect you find a lot of debris in the pan.
Brad

 

Thanks for your help!

The previous owner installed a crate engine and rebuilt the transmission soon before we acquired it.

There is no cooler return line filter which indicates that the shop that rebuilt the transmission likely took other shortcuts as well. Flushing and cleaning the cooler lines will not guarantee clean lines because the metal particles that the previous failing transmission produced mix with the transmission fluid burned solids and are glued to the cooler line walls.

Here is one theory and please note that I am not a transmission expert so please feel free to administer the "Left Right Left Right" glove slap if required.

I think that the 3 hour drive caused debris to collect in and around the shift solenoids. Since the blazer was in OD the entire time I think that both solenoids we're off. At the conclusion of the freeway run and acceleration was initiated from a standing stop one solenoid hung up on debris which caused an aberrant pressure rise across the metering block which stuck it in 3/4. This condition was observed up to the moment the blazer was turned off for the evening in the motel parking lot. During the night the pressure equalized across the metering block and solenoids. When the blazer was started the next morning the solenoid for R/1/2 fully opened or closed as the case may be and the solenoid for 3/4 hung up on a piece of debris. This theory would explain the change in shift pattern from the previous day to the next day. Burned chaffed or otherwise damaged shorted or open circuit control wiring to the solenoids could possibly cause the same symptoms. My sense is that the shifting issue is less likely to be caused by an electrical problem because in 6 months of service since the Bakersfield trip the transmission operation has been consistent.

Please advise, thank you.