77 C-10 HELP No front wheel drive !!!

[Roger in Republic]

I need some help finding out why my front end is not working. The truck is a 77 C-10. 400 / 400 with an NV 203 X-fer case. The first time I tried to use the snow plow I noticed that I had no front drive. The hubs are engaged, the t-case seems to shift OK. The truck will move in 4 Hi , 2 Hi and 4 loc but there is no power to the front end. Could this be a broken chain in the case or could it be as simple as a bum shifter? I have not been able to get under the truck yet as it wont pull the hill to my garage door in the snow. I will have to pack the snow with my wife's truck. Any trouble shooting tips would be much appreciated.

Thanks. Roger

PS there are no strange noises or the sounds of anything that may have exploded.

[motornut]

NV...or NP?
unless you have a kit the 203 won't run in 4X2
found this

How to convert an NP203 from fulltime 4x4 to Part...

its factory fulltime 4 wheel
my 78 i have to pull it all the way to the seats and a light comes on ...maybe it's stiff?
low or high loc puts the axles together,no slippage

Lo-Loc (Low range, center diff locked)
Lo (Low range, center diff unlocked)
N (No drive to axles)
Hi (Hi range, center diff unlocked)
Hi-Loc (Hi range, center diff locked)

with the kit low and high is 4X2



mine locked in 4X4 and had to drive it home with the hubs locked out
normally it's plugs not hubs
my 79's plugs

[Roger in Republic]

thanks Motornut. The shifter plate shows 4 loc at the top toward the dash board. I am not the first owner so I don't know if it is the stock plate. The truck was ordered with a snowplow front spring option but without positraction diffs. I am only guessing that I have a NP 203, It sure looks like one. As I said above, The truck will move when shifted into any gear other than Neutral on the transfer case but there is no power to the front diff. Is there an easy way to check if the chain has broken or the drive gear grenaded?

[motornut]

Originally Posted by Roger in Republic

thanks Motornut. The shifter plate shows 4 loc at the top toward the dash board. I am not the first owner so I don't know if it is the stock plate. The truck was ordered with a snowplow front spring option but without positraction diffs. I am only guessing that I have a NP 203, It sure looks like one. As I said above, The truck will move when shifted into any gear other than Neutral on the transfer case but there is no power to the front diff. Is there an easy way to check if the chain has broken or the drive gear grenaded?

With it in either hi or low lock
Hubs locked in
Front should be locked to back of course
Now undo hubs see if front shaft moves

Other then lifting the whole truck up
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[Roger in Republic]

I will check it out tomorrow. I will have to plow anyway, we are expecting 6 to 12 inches tonight and I hope it is powder.

[Roger in Republic]

Problem solved and I feel so stupid. As I said, this truck has open spools in both differentials. How anyone can call this thing a four wheel drive is beyond me. With open spools (Non- Posi), if one wheel loses traction all the power goes to that wheel. Soooo, if one of your hubs is unlocked the differential sees that as an unloaded wheel. I was sure that I had locked both hubs. Just to be sure I checked them and sure enough, right hub was in the 'free' detent. Either I screwed up or my helper unlocked it thinking he was locking the hub. I locked the hub and "Surprise" power to the front end. So thanks to you guys who helped out. I learned a lot during all the research I did on the NP-203. I am thinking about adding some Aussilockers to both ends of this old beast so I will have real 4 wheel drive. Thank again,

Roger

[MadManAndrew]

Just to note, a "C10" is 2WD, a 4WD is called a "K10". That's a funny slip on that unlocked hub though.
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[Redcap]

This is a spool. It permanently locks both axles together.



You simply have an open differential.

[Roger in Republic]

Mad man, when the PO repainted the truck he left the badges off. C? K? Who knew? Thanks for the clarification.

Redcap, In all the years that I have worked on cars and trucks( 50 years ) the one thing that I avoided is third members. Sorry I muffed the terminology, I have never been inside a differential although I have seen them on TV. Someday I might just take one apart, as long as I never need to put it back together. Thanks for straightening me out though.

[Redcap]

Originally Posted by Roger in Republic

Mad man, when the PO repainted the truck he left the badges off. C? K? Who knew? Thanks for the clarification.

Redcap, In all the years that I have worked on cars and trucks( 50 years ) the one thing that I avoided is third members. Sorry I muffed the terminology, I have never been inside a differential although I have seen them on TV. Someday I might just take one apart, as long as I never need to put it back together. Thanks for straightening me out though.

No problem, hope you didn't take it the wrong way.

[Roger in Republic]

Redcap, Not at all. I appreciate being given the correct terminology. By the way, I notice that you are located down in Lewis county. I went to school at Centraila College in the late 60's. Lived out in Adna. Learned to fly out at the Chehalis airport. A lot of nice folks down that way.