Hello Guys, I am a first time poster here so be gentle.

I am also new to the K5 world. I have a 1984 K5 with the 350 700r4 transmission and NP208 TC. I am not able to completely diagnose my problem.

Here is my story: I can start the blazer cold and drive it around locally, it shifts fine up through the gears up to say 50-60 MPH. I can slow back down and start again, I can punch it and it reacts. However, My problem begins after driving for a significant time, 5-10 miles, I then come to a stop and try to proceed, then it feels like all of the gears are gone, NO drive, No reverse etc...at that point when I try to put it into park it grinds, sounds like something is still spinning.W

With trial and error I have found if I put it into neutral and engage the 4wheel drive and shift it into 2hi and then put it into drive I can move forward. I then switch back to 2 wheel drive and then I can shift normal and drive again.

I have been trying to sell this blazer and when i am asked if there are any issues I can only say "The tranny slips" I cannot say if it is a cheap fix or if the tranny or TC needs replacing.

I can supply additional info, I just do not know what information is needed.

Any help you can provide would be great.

Thank you som much for your time.

 

Try getting the tranny fluid changed, if the tranny fluid doesn't smell burnt or has a black or dark brown color to it changing can help the transmission or completely kill it if it's on dreath row. If the fluid is burnt with a dark color besides red changing it can kill it; I don't know exactly why, but it happens.

Also, check all your cables going to the transmission. I don't know if your truck has a TV cable going to transmission, if it does adjust it to the proper tension. A loose TV cable will usually cause a transmission to slip and not shift properly.

And make sure your transnission is filled to the proper level with transmission with transmission oil. It may just be low.

 

Thank you Matthewp,

I had previously pulled the pan, the fluid was pinkish, not hint of burning smell. There was little to no shavings in the pan. I replaced the filter and gasket and topped it off with new fluid. I do not know much about the TV cable, I know where it is. I am looking for it being loose? Not sure how to adjust, there are tutorials on here I am sure. I have noticed that there are two electrical connections on the tranny, one is connected and the other is not. Not sure where the second one goes or where it is coming from, or if it even applies to my application.

Thank you again

 

The TV cable (or Throttle Valve Cable) is used to control transmission pressure. It should be tight. A loose TV Cable will cause the transmission to slip while shifting, so it should be tight. Usually the TV Cable is located on the carberator or throttle body right next to throttle pedal cable. The cable you see on the transmission is probably the gear selector cable, and electrical wire are going to reverse lights and maybe a neutral safety switch.

Send me a picture a of your engine bay on the driver's side. I might be able to help you a little better in finding the TV Cable.