NP208 help needed

SHINTON

SHINTON

Well-Known Member
Joined
Mar 17, 2005
Location
Triad area of NC
Ok, would like some feedback on my reasoning and logic, thoughts, suggestions, parts, vendors and so on!

88 Blazer, has auto tranny and NP208 transfer case, truck has 1.5" body lift on it and we know the linkage is off a bit because of that.

About a week ago I decided to test out 4wd, at this point I have put about 600 miles on the truck since I bought it a month or so ago. Keith had adjusted linkage a bit before I bought it, never a lick of trouble and he is on here as well and may chime in.

So I put in 4 Hi, 4 Low, confirmed it is all working good about a week ago, and then I have driven about 150 miles probably since then. Driving to work this morning as I came around curve on highway, ugly grinding sound (like a manual trying to mash into gear) for just a moment, stops, still driving ok. I am doing 55ish maybe and happens again say 30 seconds later and I start pulling over and by the time I am stopped I have "no power."

Originally I thought I lost the transmission, but worked through and figured out that if I put in 4 Low, truck will drive, shift all three gears (and do maybe 15-20 mph) Put tranny in neutral, tcase back in 2HI and put in gear and it drives again!! Drove on to work about 3 miles or so, several stops and starts, turns, etc.

Go to run an errand, came around curve into parking lot, no power (as if I am in neutral in tcase basically) but at this point I put tranny in neutral, (stopped moving also) 4 LOW and finished my errand to bank and then back up hill 1/4 mile to office.

Every time I have tranny in neutral and try to go from LOW back to 4 high / 2 high i get grinding. Turn engine off, tranny in park put in 2 hi / 4 high, start truck, shift to R N D and nothing as if tcase in neutral, try to put back into park and GRINDING noise!

So I think maybe a linkage issue, get under truck, manually move the rod between 2 HI and 4 HI, I can feel it moving solidly but still nothing, as if my HIGH range is not engaging at all.

Here is where I want to get some help / logic. I "don't think" I stripped the HIGH range gears / teeth mostly because if I had, could not have gotten back into HIGH and drove another 3 miles.

What I "think" is that there is something internal in tcase that "shifts" you into HIGH from Tcase neutral and that part is basically not engaging. I have done a tiny bit of research and shifter / forks has come up and I see a part.

I am hoping someone understand the internals of NP208 a bit more and might can explain in layman (does accounting for a living) terms. Basically what is the part that might be broke / not engaging?

http://www.drivetrain.com/images/stories/product_imgs_large/np208mw_large.jpg

I am guessing maybe part 31 or 35 in that picture is the fork and below is link to that part. I am guessing one of them is for HIGH and the other for LOW gear.

Transfer Case Repair Parts Online - NP208 Shift Forks
Rebuild Kits NP208 Transfer Case Parts Illustration and parts list, you save moneys! - Drivetrain

So, any help is appreciated. I am in Triad area, truck is in Greensboro, if there is local person you would recommend to diagnose and rebuild / fix it I would love to have a name and shop.

Another option is a 2nd NP208 I can pick up from Keith, works fine but leaks terribly. In theory I can buy a "gasket kit" for $25, but again need someone that can rebuild and swap out tcase? Tax season, busy and need it faster versus waiting on me. In this case would rather spend the money and get done since this is supposed to be my "winter" truck.

Thanks in advance for the help!
 
It sorta sounds like the body is flexing on the frame and popping you out of gear. That's just what I gathered with a quick skim through all that.
 
I agree, bumping, moving etc probably 'moved' the linkage to cause it to bump out of high range. But as I research move it is sounding like worn forks or the "boots" (plastic bits) that is allowing it to pop out of gear into neutral and basically even moving manually (linkage essentially disconnected) it is not going back into high range gear. I can put in LOW range gear... Now I am thinking more about finding local places, who would remove / replace the t-case for me and install new forks, (plastic bits) and maybe other parts as desired and worn out!?

Anyone local want to make some "good" side money? Lots of youtube videos on how to do this, feeling more confident on the diagnosis but time is gonna be my issue.
 
Just to clarify, your saying the truck will no longer move? If yes , then it sounds like the collar (parts 70-75) are not engaging. It could have been damaged when it popped out on the highway. But this is only a guess I haven had an Np208 apart.
 
If I shift tcase into LOW it moves just fine, tranny shifts fine, moves in and out of Park, Reverse, neutral, drive etc. But at this point basically I cannot get it back into HIGH range (2 or 4 high) at all, grinds if I try.

Thinking about that a bit further, if my tcase is in neutral, tranny in park, is the truck really in neutral, could be moved around or somehow still really in Park? Makes my brain hurtz...
 
SHINTON said:
If I shift tcase into LOW it moves just fine, tranny shifts fine, moves in and out of Park, Reverse, neutral, drive etc. But at this point basically I cannot get it back into HIGH range (2 or 4 high) at all, grinds if I try.

Thinking about that a bit further, if my tcase is in neutral, tranny in park, is the truck really in neutral, could be moved around or somehow still really in Park? Makes my brain hurtz...
Click to expand...
Yes, if the t-case is in neutral then the truck can roll even if the trans is in park.
 
Yes, got under truck, loosened up the linkage at the shifter end and then moved by hand at transfer case. So I felt like i was moving solidly between 2 HI and 4 HI, but in either case no go, essentially acting as if still in neutral. Hmm, did not think about chocking tires to keep blazer in place, not that it would go far but might call and ask the boss to throw something under the tires! :)
 
My 79 burb had a issue similar to this sorta, turned out the linkage for tcase was loose not allowing it to go all the way into 2wd,4wd and when it would go into gear it would slowly grind after so long then no power got anbuddy to cycle tcase lever while I was under it and noticed it! Hope it’s that easy for you but not sure if it’s same issue! I’d def Check mounts for trans and tcase they can cause a ugly grind my k5 lost trans bushing and sounded like it was blowing up around curves!
 
I'd rule out linkage issues and engine/transmission mount problems before going further. Make sure it's actually falling into the detent for each gear. If you rule all that out, then consider an internal tcase problem. The biggest issue you'll see is on decel is that worn forks and/or worn thrust bearings will allow the sun gear to move far enough to pop out of gear. So long as you keep it under load, it'll stay in gear, but lift going downhill, and it'll pop out of gear.
 
The grinding when trying to switch back from low range to high range is somewhat normal.

Best way I have found to make this shift smoothly is to be rolling very slightly, bump trans to N and then shift very quickly between the ranges, taking care not to stop in N on t case. Barely rolling helps keep the t case from being in a bind.

If I can’t make the shift quickly, then I stop completely and shut the truck off then shift.

Typically I can shift very easily from 2-4hi, but it takes some practice going between ranges.
 
As this point running, not running, manually moving it by hand under the blazer, cannot get it to engage back into high range at all (2 or 4hi). I suspect the fork or the plastic clips or something inside has moved around enough to be an issue.

I have a flat quote to remove, rebuild and reinstall the transfer case of $675 from Billys Transmission in High Point. That sounds like a workable plan for me and will be trying to work my way down there this week.

Sammy


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SHINTON said:
As this point running, not running, manually moving it by hand under the blazer, cannot get it to engage back into high range at all (2 or 4hi).
Click to expand...

Is that with the shifter disconnected, and you just trying to move the little lever bolted to the shift shaft? I'm 100% with Shawn's post above.
 
SHINTON said:
I have a flat quote to remove, rebuild and reinstall the transfer case of $675 from Billys Transmission in High Point. That sounds like a workable plan for me and will be trying to work my way down there this week.

Sammy


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Click to expand...

No way I would pay that. You should be able to find another used case for $100-$150. Buy a transmission jack from HF, and do it yourself.
 
Yeah i “loosened” the shifter, really easy just a nut in front and rear on that rod so I have plenty of wiggle room and then basically I could push/pull from the tcase end. (It was moving shifter but no binding from shifter)

$150 say for another used tcase that may or may not have the same issue in a day, week, month? I actually can get one from prev owner for free but it leaks like there is no tomorrow which is also a PITA.

I started ‘tax season’ and my saturdays are now shot until April 16th....

I might could save 3-400 if I replaced with used unit that I rebuilt myself, but my question is which is worth more to me right now. My time / busted knuckles, LOTS of cussin, or pay an expert? A times it is worth the expert, call it my “tax” for not having the time, if this was 4/16 I would do it all myself just for the learning but I need to drive this truck before that so...


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