Transfer Case Issue?

[Caeadiel]

Hi All, new to the forum. Hopefully this is the right section to ask this. I think I may be having issues with my transfer case. A couple of weeks ago I ran up to the hardware store and got back no problems. Then the next weekend I was going to do some chores and needed the truck. Loaded it up and got in and put it in drive but no dice, nothing happening. I tried to put it back in park and lots of grinding. So I shut it down and then put it back in park.

From what I read, it sounds like it might be the transfer case but not positive. Not sure which transfer case I have, the shifter has Lo Loc, Lo, N, Hi, Hi Loc if that helps. Mostly looking for confirmation if it might be the issue or if there is something else to check.

 

[idahovette]

Check your transfer case, make sure it's in a gear?? Pull back or push forward, see if you can feel a detent, the try it?? I think what you have is a 203 case.

 

[Caeadiel]

I did try that, I pulled it all the way to Hi Loc, then moved it one forward to Hi but still the same issue.

 

[Strick]

Welcome to the party from NC! Sounds like a 73-79 NP203 by your description. Shift the case all the way to the seat & then back forward a click. That should put you in 2HI. These cases get sloppy over 50 years of use & are notorious for jumping out of 4x4.

HS

 

[Old Guy Bill]

Welcome to the party from NC! Sounds like a 73-79 NP203 by your description. Shift the case all the way to the seat & then back forward a click. That should put you in 2HI. These cases get sloppy over 50 years of use & are notorious for jumping out of 4x4.

HS

From your description that’s definitely an NP203, and there is no 2H, it’s all time 4WD, unless it’s been modified. If it has been modified with a
“part time” kit the shifter pattern is different than what’s shown on the shifter.
When the TC is in the very center position, it should be in neutral, and shifting the truck transmission to any position shouldn’t cause any grinding.
Does it have gear oil in it? Have you checked the level?
The shifter has two levers on the TC, they could be loose or need adjustment.

 

[74Blaze]

The Transfer Case shifter could be worn-out. When I bought my Blazer it wouldn't shift into the Lock position so 4-wheel drive didn't work. I ended-up changing to an aftermarket twin-stick shifter.

 

[Caeadiel]

Thank you all for the suggestions. I will try different positions on the shifter to see if that does anything. I am pretty sure it is the original case still, since it was mentioned it did occur to me that it is full time four wheel since when I drive it I notice that little "surge" or what ever you want to call it when turning in a tight spot since the front wheels are trying to turn at the same rate.

For the gear oil, any particular type that is recommended or just something like this?

https://shop.advanceautoparts.com/p/valvoline-flex-fill-transmission-differential-gear-oil-full-synthetic-75w-90-1-quart-889785/12507273-P?selectedStore=7048

 

[idahovette]

^^^^^^^^^^NO NO NO GM recommended motor oil...10-30, 10-40. Too thick and you can stretch the chain.....more^^^^^^^^^^

 

[GTX63]

I've experienced the gear jump with several trucks. I'm working on a 79 GMC right now with the same issue. The previous owner let the truck sit outside, never used the floor shifter and it rusted stuck. However, over a few weeks if driving, it would randomly jump out of gear and grind if I attempted to put it in park. Same transfer case as yours-a 203. On the most recent truck, I removed the shifter, soaked it and freed it up, did a transmission service and the issue is gone.

 

[Caeadiel]

^^^^^^^^^^NO NO NO GM recommended motor oil...10-30, 10-40. Too thick and you can stretch the chain.....more^^^^^^^^^^

Just to make sure I understand, you're saying to use 10-30 or 10-40 motor oil?

 

[idahovette]

That's what GM recommended in the 70s when these cases first came out. That's what I have used exclusively in my 75 K20 since i bought it brand new June 1975.

 

[Caeadiel]

I'll be taking a look at it this weekend. For checking the fluid in the case, where is the plug and how full should it be?

 

[AuroraGirl]

Just to make sure I understand, you're saying to use 10-30 or 10-40 motor oil?

Yes. Conventional stuff you can buy in a bulk jug at the tractor supply store if you have one, cheap and will work for this. gm originally called for 10w30 engine oil iirc

 

[Caeadiel]

Confirmed the linkage is moving so that shouldn’t be an issue. Haven’t added any fluid yet as I saw at least one spot that was leaking so I ordered a gasket kit to replace that before I do so. Also got a pump to help fill it.

 

[Caeadiel]

Planning on getting to this on Sunday but wanted to ask, what do these bolts get torqued to? Pic is not mine, just grabbed it off the net but I have to replace this gasket.

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