Oh Boy!!!!

[paxfam1]

Alright 98 Blazer

Out on lake doing some ice fishing up here in Minnesota(damn Cold).

Driving across the ice and hit a big drift, yeap she is stuck. So I am shifting back and forth from Drive and Reverse in 4x4 3 button push. Bout 10 shifts, and then I started getting the sound of two gears slipping, and the tires didnt appear to be spinning they just kind of jolted a little, so I would let off the gas and shift gears and sometimes it would catch and the wheels were normal again, but then after shifting that noise was back, best way to describe it was like a ratcheting noise. So I finally get out and all is good, noise is gone, 4x4 is working. Somthing must be wrong but, not sure what. I mean being stuck in the snow is not much load on the tires, I can sit on dry pavement and smoke them all day long and never have herd that ratcheting noise.

[Blue Bowtie]

Check the cable from the actuator to the front diffy. Since it it basically hanging out ther in the breeze, it may have been bound or kinked after having settled into the drift, then retunred to normal once you got off the drift.

[paxfam1]

alright was playing in the snow today, 4x4 not working at all. The front drive shaft is engaged all time, in 2wd and 4wd, but front diff is not engageing. What would cause this. I plan on pulling it into the shop and looking at it this evening. Any tips would be helpful.

[paxfam1]

Originally Posted by paxfam1

alright was playing in the snow today, 4x4 not working at all. The front drive shaft is engaged all time, in 2wd and 4wd, but front diff is not engageing. What would cause this. I plan on pulling it into the shop and looking at it this evening. Any tips would be helpful.

UPDATE::

Shaft appears to be engaged even with blazer off.

[paxfam1]

Originally Posted by paxfam1

UPDATE::

Shaft appears to be engaged even with blazer off.

Update:
Pulled vacume line off the actutator under the battery and released pressure and the shaft is now disengaged. Is this normal to have pressure after its off? if I do have vacume, then why isnt the front diff enageing?

SO this is where im at right now, shaft is staying engaged all time and wont engage the front diff.......What gives what should I look at now???????????????????

[paxfam1]

alright, my bad

jacked up the front only to find that the front diff is engaged full time and the t-case is not engageing. So now what, I here the motor switching gears down there when I push 4hi and 4lo but tcase is not engaging. where do I go from here??

[Blue Bowtie]

Look at the actuator in the front axle. It is apparently not locking in the side gear.

The front driveshaft may turn so long as there is no resistance at the front axle (gears not engaged). Engage 2HI and shut off the engine. With the vehicle OFF, can you turn the front driveshaft?

[paxfam1]

OKay this is whats happening.......

front diff is enaged so no I cannot turn the shaft, which I think is how it is supposed to be, if I pull the vacume line to the actutator the pressure is released and the front diff is disengaged, so then the shaft will turn freely. But when I put it into 4hi the t-case appears to be not enageing. Some times when it is in 4hi and I am spinnning the rear tires I can here that ratcheting sound from the t-case, its a noise like its not fully engaging, just rubbing teeth or something. As for 4lo it makes the clunk, and is geared down but once again t-case didnt engage the front shaft.

[old_master]

The NV233 selectable transfer case is used on your '98 Blazer. Both drive shafts are "live" at all times. They both turn simultaneously when the vehicle is in motion. The front differential is locked to power when the actuator is activated by changing the mode switch to 4HI. 4LO is accomplished when the encoder motor changes the gear range in the transfer case.

Put the mode switch in 2HI. Put the transmission in park. Raise both front wheels off of the ground. Leave the rear wheels on the ground. If you can turn your front drive shaft, (by hand) there is a problem in the transfer case.

[paxfam1]

My front passenger side axle is staying engaged, its getting vacume to the actuator even when in 2wd, even with it not running..... With the front wheels off the ground I can spin the front shaft but its also spinning the front passenger wheel. Meaning the tcase is not engaged. But you say that the front shaft is always engaged, but that is not the case because when it was functioning I was watching that shaft and it would turn when in 4wd but when in 2wd the shaft did not turn. I remember that from when I had vacume problems to the front diffrential about 1 month ago.

[old_master]

No surprise there. When you were in 4WD the actuator locked the axles to the drive shaft. In other words, the axles were powering the drive shaft.

[paxfam1]

No, see the vacume line fell off the actuatator so the front diff wouldnt engage at all, but when I hit 4 wheel the shaft would spin and when I hit 2wd the shaft didnt. So oviously that shaft isnt live all the time, only when in 4wd.

So I got a front driff with the passenger side axle enaged full time(actuator is engaged),and a tcase that wont engaged the drive shaft..So my front shaft is turning but its only because the front diff is locked in, in other words there is no power to the front wheels

[Blue Bowtie]

Originally Posted by Blue Bowtie

The front driveshaft may turn so long as there is no resistance at the front axle (gears not engaged). Engage 2HI and shut off the engine. With the vehicle OFF, can you turn the front driveshaft?

So if I understand all your testing thus far, when the vehicle is on the ground, the engine is off, the transffer case selector is in 2HI with no vacuum at the front differential actuator, and you have verified that the actuator has mechanically released at the differential (no stuck cables), you can manually turn the front drive shaft? That might be a problem.

The "ratcheting" sound may be an indication of a stretched chain in the xfer case. How many miles are on the vehicle?

[paxfam1]

No, with the vechile on the ground in 2hi with motor off the front diffrential is staying engaged, the vaume is holding it, if I pull the vacume line, the front diff will release, I can then turn the front shaft. But the transfer case does not seem to be locking in because when the front diff is locked in the wheels wont spin, So I think that the vacume switch in the transfer case is stuck, that is why there is constant vaume to the front diff, but this doesnt explain the transfer case not engageing does it?

There is 157,000 miles on the beast............

[old_master]

Transfer case operation can get quite technical. I will keep this as easy to understand as possible, so that anyone that reads this, regardless of his or her technical aptitude, can understand it.

The NV233 selectable transfer case has a sprocket on the rear output shaft. The rear drive shaft is connected to that shaft. There is also a sprocket on the front output shaft. The front drive shaft is connected to that shaft. A chain connects the two sprockets so that both drive shafts rotate at the same RPM simultaneously. Any time the vehicle is in motion, both drive shafts, all four axle shafts, and both front and rear differential carriers rotate. The rear axles are both “locked” to the rear differential carrier at all times.

When you change the transfer case "Mode" from 2HI to 4HI, the vacuum actuator, located under the battery, moves a pin that locks the right front axle shaft to the front differential carrier and the front differential now becomes “live”, just like the rear differential.

When you change the “Range” from 4HI to 4LO the encoder motor, mounted on the transfer case, changes the output shaft gear ratio by changing to a different set of gears in the transfer case.

If the pin that locks the right front axle to the front differential carrier remains engaged after changing the mode to 2HI, (as with an actuator or cable failure) the vehicle will remain in 4HI. If the chain now fails between the two output shafts, the front differential carrier, front axle shafts and front drive shaft will still rotate as a unit. However, the assembly will not be “live”. Only the rear wheels will power the vehicle.