Been a while (bought a motorcycle) but now its winter and driving the old hoe again. She has been missed. Since purchase my 99 2dr has not had a working 4wd. 30k on new motor and trans. So now I am thinking its time to tear into the transfer case to find out whats going on. The actuator is working. Its been slowly leaking from the case since purchase but not sure where from. I will be posting pics as this is the first t-case I will have pulled but am not too concerned. Those who have pulled to diagnose and or repair any insight or tips will be appreciated. I do have a repair manual so I will follow that but its like a recipe. Its more of a guide then a step by step in most cases.
Floor shift time to drop transfer case
- Thread starter AZ Tahoe
- Start date
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autolover3
Full Access Member
i just rebuilt my np246 t case in my 99 yukon. What problems are you having? My chain was so worn it was skipping and when you would accelerate or turn in 4wd.. bang bang bang clunk clunk almost like a worn cv. Chain was riding on case on the inside. Pumps also like to wear through spring and into the case creating a hole and they will leak. I got a upgraded pump from Merchant Automotive along with rebuild kit and new chain. Refill with blue autotrac fluid.
---------- Post added at 11:21 PM ---------- Previous post was at 11:19 PM ----------
While it was on the lift I also drained front and rear axles.. refilled front with 75w-90 synthetic... lower viscosity helps in winter when its cold and your not using 4wd
---------- Post added at 11:21 PM ---------- Previous post was at 11:19 PM ----------
While it was on the lift I also drained front and rear axles.. refilled front with 75w-90 synthetic... lower viscosity helps in winter when its cold and your not using 4wd
Only problem is it has never worked and a small leak from somewhere. When I engage it feels like it engages but no luck. I know it has a new motor and trans so I am guessing that when they installed those they messed something up with the transfer case. I have checked the actuator which does work and the interior light comes on suggesting its in 4wd. Not really sure what the deal is but I am sure I will find out quickly when I pull it off and take a look
I will be repairing mine soon, makes some strange noises, I plan on rebuilding it completely, are there any specialty tools or specific procedures to carry out the rebuild? Does anyone sell a complete kit with pump, chain and clutch pack?
---------- Post added at 07:17 PM ---------- Previous post was at 07:15 PM ----------
Definitely keep us posted on your findings...
autolover3
Full Access Member
I ordered a rebuild kit and chain from Merchant Automotive.. they specialize in GM and I'm not sure if it's related but Youtube "nastygirl duramax"... has a big ol' MA sticker on rear window and she sure hauls ass. They also have seal driver kits etc. I bought the upgraded pump to prevent future rubbing. When ordering a chain there is two different types.. your current chain may have 1 blue link or 3 blue links. Check your case halves to make sure chain wasn't rubbing through and hopefully your pump clip is still intact in rear case half. GM came out with a TSB and a upgraded special blue coated detent plunger for encoder motor, I ordered that through dealership and installed since I had t case apart. Other than that just check everything over such as sprocket teeth wear and planetary gears etc. Try to lay parts out in a line or in order as you take them apart so re-assembly goes a bit smoother. Any other questions just ask, sorry for long post but I'm trying to get all the info out I can before i forget what I all did haha.
Oh and make sure to remove speed sensors and underneath/behind the little oval grommet on rear case half between the sensors is the snap ring. You spread it open into case grooves and the half should come off output shaft, may need a hit with a deadblow.
Oh and make sure to remove speed sensors and underneath/behind the little oval grommet on rear case half between the sensors is the snap ring. You spread it open into case grooves and the half should come off output shaft, may need a hit with a deadblow.
autolover3
Full Access Member
I just noticed the thread title says "floor shift"... Mine is an automatic push button 4wd NP246. Is yours push button too or lever on floor...That may alter my guess haha.
If it's push button I would say encoder motor is bad and isn't moving shift fork in t case to lock it in. If it's floor lever I'll need to look at some exploded part diagrams to try and help ya.
If it's push button I would say encoder motor is bad and isn't moving shift fork in t case to lock it in. If it's floor lever I'll need to look at some exploded part diagrams to try and help ya.
SunlitComet
OBS Jedi-Do Good
The if your 4hi or low on the shift console or button panel lights up continuously then your actuator and feedback sensor are working and it is very possible that the shift fork or collar is broken in the front axle leaving the diffy carrier not fully locked to the rest of the drivetrain( the left side wheel axle is always connected the the diffy whereas the right side is disconnected or connected as needed for 4wd.).
