1980 Sierra K15 NP205 Stuck In Neutral

[GTX63]

Brought a 1980 GMS Sierra Grande home last week. It is a project for my son and I. The guy told us that the transfer case was stuck in 4D High. I drove it on the trailer without issue. After we got it home, my son pulled the front driveshaft. I tried to back it off the trailer and it will not move. I can feel the transmission drop into reverse or drive, but that is it. When putting it back into park I can hear grinding. I have tried messing with the linkage. The shifter moves from 4low to4 high fine, but I believe only one of the shifting tabs moves where they attach to the TC. Just look for some direction. Thanks.

 

[Strick]

Look at the two shift rails on the t-case where the shifter linkage goes. If they are rusty then I'd spray them with some WD40 before proceeding. The two rails are plunged in and out of the case by the lever on the linkage. I have had a NP205 hang up while I was out on the trail. I had my wife pull back on the shifter (was in 4-Lo) while I took a ball peen hammer and tapped the opposite piston that was engaged. This freed up the case and I had no issues with it after this one episode. You may need the truck running and trans in neutral while doing this but remember to set the parking brake just in case.
Good luck from NC.

Strickland

 

[Bextreme04]

The NP205 has two bars with a link bar that then connects to the shifter. Get under there and take a picture of the shift lever connected to the linkage and link bars. We can then help you correct any issues you might see from there.

My 1980 K25 has an NP205 that I rebuilt. It is a bit of a pain to get between positions, but does shift fine between them. You can go between 2hi and 4hi while the transmission is in N. Just give it a sharp whack on the shifter to knock it between the two(they are the two positions of the shifter furthest to the rear). Don't go through N on the NP205 without the trans being in Park, otherwise there is nothing to hold the transmission from spinning and you will grind gears when you try to put the transfer case into gear.

 

[nvrenuf]

@GTX63 All 1980 GM 4wd's should have an np205 but(!) it's also now a 42 year old truck so you never know what has been done to it or changed on anything with a few years on them. Not moving after pulling the front driveshaft sounds a lot like the behavior of an np203 full time tcase. Can you post a pic of the tcase to verify exactly what it is?

 

[GTX63]

@GTX63 All 1980 GM 4wd's should have an np205 but(!) it's also now a 42 year old truck so you never know what has been done to it or changed on anything with a few years on them. Not moving after pulling the front driveshaft sounds a lot like the behavior of an np203 full time tcase. Can you post a pic of the tcase to verify exactly what it is?

Lol. You are correct. It was originally a 6 banger that had a crate 350 installed unknown years ago. It has been a farm truck until the 83rd owner bought it 2 years ago. He couldn't get it out of 4wd so he just drove it around his 7 acres like that. I assumed it was a 205 but I didn't confirm it. Yes, it is full time 4wd.

 

[GTX63]

Look at the two shift rails on the t-case where the shifter linkage goes. If they are rusty then I'd spray them with some WD40 before proceeding. The two rails are plunged in and out of the case by the lever on the linkage. I have had a NP205 hang up while I was out on the trail. I had my wife pull back on the shifter (was in 4-Lo) while I took a ball peen hammer and tapped the opposite piston that was engaged. This freed up the case and I had no issues with it after this one episode. You may need the truck running and trans in neutral while doing this but remember to set the parking brake just in case.
Good luck from NC.

Strickland

WD40 to the rescue. I pulled the boot from inside the cab, checked the bolts connecting the shifter to the linkage and sprayed from top to bottom. Worked everything back and forth for about 5 minutes. Started the truck, kept the transmission in neutral and kept working it until I felt the truck start to move. Success. Thanks much.

 

[Strick]

NP205's are the best. They usually work with no issues and are built like a tank. I have a couple trucks with them now. This group loves pics so post some up and we'll see you around.

Strickland

 

[GTX63]

I'll try to post some pics if I get another chance. I parked it in our barn away from the house. I don't plan on putting the front shaft back in for some time as the bed and front clip will be coming off and prep and body work begin. Amazingly, the owners manual was still in the glovebox.

You must be registered for see images attach

 

[GTX63]

NP205's are the best. They usually work with no issues and are built like a tank. I have a couple trucks with them now. This group loves pics so post some up and we'll see you around.

Strickland

Will do. We also have an 85 K10 Silverado we'll be tearing down and bringing back to life over the winter and spring. Thanks again.

 

[Strick]

My first Square was a '76 LB 4x4 High Sierra. Crimson Red with a White top. Good luck with your build. Maybe you and your son will have a great time and make some lasting memories all the while fixing up a good ole truck.

Strickland

 

[AuroraGirl]

Brought a 1980 GMS Sierra Grande home last week. It is a project for my son and I. The guy told us that the transfer case was stuck in 4D High. I drove it on the trailer without issue. After we got it home, my son pulled the front driveshaft. I tried to back it off the trailer and it will not move. I can feel the transmission drop into reverse or drive, but that is it. When putting it back into park I can hear grinding. I have tried messing with the linkage. The shifter moves from 4low to4 high fine, but I believe only one of the shifting tabs moves where they attach to the TC. Just look for some direction. Thanks.

why did you pull the driveshaft?

 

[GTX63]

Bad U joints.

 

[AuroraGirl]

Bad U joints.

Although I understand why you did, but just be careful, im not confident on what im about to say because its been a long time since the topic was discussed but I believe if you pull that front shaft and your case is stuck in 4hi or 4lo that , i believe, puts a lot of stress on the case. but it is a 205 ,so for your purpose i cant imagine it harmed much
By chance, is your np205 a slip yoke model

 

[GTX63]

Although I understand why you did, but just be careful, im not confident on what im about to say because its been a long time since the topic was discussed but I believe if you pull that front shaft and your case is stuck in 4hi or 4lo that , i believe, puts a lot of stress on the case. but it is a 205 ,so for your purpose i cant imagine it harmed much
By chance, is your np205 a slip yoke model

No, I did some checking. The truck is for certain a 1980 model, however the TC, and it is original, is a 203. They must have been emptying the old stock as this one was rolling down the line.
The issue was definitely linkage related.

 

[nvrenuf]

No offense but how can you be so sure that the 203 is original in a 42 year old truck you just bought used? What exactly did you check?

It is simply not possible for the truck to be an '80 and have originally come with a 203, you would literally have to have a one off truck. No other tcase was used by GM in 1980 than the np205.