95 Blazer 4WD problems

[Dave186]

I know Ive asked this question before but until today I havent been able to check things. My 4WD will engage but will not disengage. Old Master told me to check vacuum lines which today I did. I took out the battery box and put a line on the actuator and sucked on it and it seemed to hold vacuum the cable moved about half an inch like he said. I traced the vacuum lines back to the transfer case. There is a Y connector on the lines and one of the lines is burnt in two that comes off of it. But the one from the actuator to the transfer case is fine. Right out from the actuator there is a T connection and a larger vacuum hose goes to it and it has an electrical switch hooked to some kind of vacuum thing.
I have NO clue what to do now. I dont know where the burnt line goes to or anything. It was mentioned once that there was a line that came off and ran up beside the trans filler tube with some kind of filter on it but I dont see that at all.
Please help. And Im sorry if this is confusing I tried to word it best I could hopefully someone will be able to understand it. Im willing to give a phone number if someone can help me figure this out.

[old_master]

On the transfer case there is a vacuum switch with 3 vacuum lines connected to it.

One line runs to the actuator under the battery. If you put vacuum to it, it should operate the actuator and hold vacuum.

The second line is a vent to atmosphere with a filter on the end. Usually it runs up the transmission dipstick tube and is wire tied to it close to the top. That line should be clear and should not hold vacuum.

The third line should have manifold vacuum when the engine is at idle. It runs to a vacuum reservoir. On your 95 there is a black plastic ball mounted to the hood. There is most likely a vacuum tee and a smaller line that runs to the HVAC system, and then to manifold vacuum. If you pull the line off of the intake manifold, the line should hold vacuum.

[Dave186]

To the best of my ability I have traced the vacuum lines from the vacuum switch on the transfer case. One to the actuator is good all the way. One up to the reservoir is good no holes.
The third line is the one that was burnt in two. Im assuming its the one thats supposed to run up beside the dipstick with the filter on the end. Where can I get a filter? I know I need to replace the hose but have no clue what type of filter its supposed to have.
Also that line has a Y connector on it. Is that from another vent? This thing is driving me crazy because I dont have a rack to put it on just laying out on the concrete.
I appreciate all the help ......Thanks

[Dave186]

Just a followup to my previous post, the other line is coming from a vent on top of the transfer case into a Y and from then on is where it is burnt in two.
Would that hose and the absence of the filter on the end cause the 4WD to no disengage? As before I do appreciate all the help

[old_master]

The transfer case also has a vent and it's possible they're teed together. If the vent is plugged, the actuator under the battery can not vent the vacuum that was necessary to apply the actuator, and it will not disengage the right front axle from the differential. As far as a filter, the auto parts stores have fuel filters for small engines, lawn mowers etc. Get one that will fit into the vent line and you'll be good to go. Post your results.

[Dave186]

Ok one more crazy question. The linkage from the cable that engages the 4WD is not connected. It had to have been in the past because Ive engaged it. I may have knocked it loose while having my hands all up in there. But the clip is missing. If its the same as the trans linkage theres a plastic bushing type of thing that holds it on. Where can I get one of those? Do they sell them at an auto parts store? I hope this is the last question and it will be all fixed and better once I do this (fingers and toes crossed). Thanks again.

[old_master]

Check the round tag on the rear of the transfer case, is the model number 231C? You can try an auto parts store. If they don't have it, you'll end up at the dealer or a bone yard.

[Dave186]

Yep 231C for sure. Getting late so I will try to finish this tomorrow. Went to AutoZone they had a packet with a few bushings in it but none would work. Will try Napa tomorrow. Thanks for the help and I will post when I get done and hopefully this fixes the disengaging problem.

[Dave186]

Ok here I am on day two. I cant find a bushing for the linkage on the transfer case anywhere Im supposing I will have to go to the dealer on that one.
Also broke a T vacuum connector on the line going to the actuator and NO one has it either, gee its becoming a nightmare. Any ideas other than the dealer on where to find these two things.

[old_master]

There's a Tee in the line going to the actuator???? Where does the other line go?
Is the vacuum Tee just a Tee, or does it have a check valve built into it? I'm surprised the auto parts store didn't have it... pretty common part. Might have to visit the local bone yard for both of the parts.

[Dave186]

Ok, Ive tried everything so far and nothing has worked. Drove it this morning and the right front axle would not release. Im totally lost ....
I read a problem another member had and hers is EXACTLY as mine is. I have the problem with the air moving from vent to defrost when I accelerate going up a hill.......anything else I can check or do.

[old_master]

Two different problems. The 4WD actuator is not releasing vacuum, the HVAC system is not GETTING vacuum. Definitely a problem with vacuum going to the right place at the right time. Kinked line, missing line, line unplugged somewhere, restricted line, bad check valve, leaky reservoir, etc etc. Unplug the actuator under the battery and plug the line. Drive the vehicle, the right front axle must disengage, if not, the clutch mechanism on the axle has got a problem.

[Dave186]

UPDATE: I was sitting around thinking about what you said about vacuum NOT getting where it needed to be and I thought I would cross the vacuum lines that come off of the transfer case. (I crossed the one from the actuator with the one going to the reservoir). As I told you I was having the same problem with another poster with the AC switching from vent to defrost on acceleration up a hill. After I switched them it does NOT do that anymore. I went up a hill at full acceleration and the air kept coming out of the vents. Is it possible that these crossed lines would also stop the axle from disengaging? I still have to get the bushing for the linkage before I can truly try this out for the 4WD but Im hopeful. Thanks.

[old_master]

"Is it possible that these crossed lines would also stop the axle from disengaging?" YES.

There is a tee/check valve in the engine compartment that looks like this: http://www.oreillyauto.com/site/c/de...4109&ppt=C0328 Manifold vacuum goes to the black fitting. Typically, one of the white ones goes to the vacuum reservoir, the other white one goes to the HVAC system. The second fitting on the reservoir goes to the transfer case. The end result is that HVAC, transfer case and reservoir must be separated by the check valve.

The vacuum switch on the transfer case is a two position switch and looks like this: http://www.dormanproducts.com/p-32645-600-500.aspx Manifold vacuum goes to one port, the vent goes to another, and the actuator under the battery goes to the third port. In 2WD manifold vacuum is corked off in the switch and the actuator is connected to the vent. In 4WD manifold vacuum is applied to the actuator. With a little fooling around, you can figure out which port goes to what.

[Dave186]

I will try to explain how this one is. The check valve you sent a pic of is connected like this. Black side is to the manifold vacuum. One white one goes to the reservoir, the other white one has a short hose and another T on it. The straight side of the T goes into a smaller line that goes into the firewall and the the other goes to the transfer case. Is that the right hookup??? I sure appreciate your help with this. All I know is when I crossed the lines coming off the transfer case the AC quit shifting itself to defrost on hard acceleration.