95 Blazer Xfer case vacuum switch

OK, did a search and couldn't find this...
Vacuum actuater to fron diff pulls in OK but won't disengage when going back to 2WD. It will eventually disengage with a big THUMP. I don't think this is good. Trying to figure out what dumps vacuum to actuater when going back to 2WD. After reading posts it appears that the switch on the Xfer case dumps the vacuum?
My question is: How in the world do you replace that thing?? Found it, looked at it but can't figure out how to do it. Any tips?

Thanks

Lynn Wagoner
Yukon, OK

The front actuator has a spring in it to pull the, er, bellows back out. Squeeze it and you will see.


Pull the hose off and engage and disengage 4x4 to see how the vacuum feels.


You might need to lubricate the line to the front axle. It could be sticking a bit.



Replacing it is a bitch. You need to get a wrench up there and unscrew it and than replace it. I got mine out and it was such a pain to put back in, I took it up to my mechanice and paid him like $15 to do it.

Enjoy.

I don't think that is the problem.

The switch unscrews.

A 7/8" box end wrench works well - did a 98 this week. Pop the formed rubber 3 vac line connector off and you got it. Yes, that 3 port switch has a vent port so when you select 2wd again vac is shut off and the vac to the front actuator and the vent port are connected and bingo, the front axle uncouples. Another problem if this does not work is that the 3 port switch is pushed by an arm in the case by the encoder motor. Try the $15 vac switch first.

Thank you Gentlemen...just what I needed to know. I'll jack that baby up when it gets warmer (big storm tomorrow) and have a go at it. You guys always come through.......

Lynn Wagoner
Yukon, OK

Update....just changed it today. The 7/8" offset, boxend wrench did the trick. Switch was stuck but you could tap on it and it would pop back out, sometimes. It was a fairly easy job.....much easier then that PITA fuel filter. 131,000 miles and it might have been factory. Could hardly blow through it. Thanks again for the help.

Lynn Wagoner
Yukon, OK

Update....just changed it today. The 7/8" offset, boxend wrench did the trick. Switch was stuck but you could tap on it and it would pop back out, sometimes. It was a fairly easy job.....much easier then that PITA fuel filter. 131,000 miles and it might have been factory. Could hardly blow through it. Thanks again for the help.

Lynn Wagoner
Yukon, OK


Small hands and arms probably made the difference. :)

I hope you checked for the o-ring when you replaced it.

I replaced the vacuum switch on my wife's 2001 s10 this past weekend. The old switch had an o-ring on it, the new one didn't. If I had known I would have bought a new o-ring but it was late so I put the one from the old switch on the new switch.

I don't understand why GM would send out a $25 part without putting a 25 cent o-ring on it.

James

The new part, purchased at Auto Zone in the HELP section for $15.00, did have the o-ring on it. Thanks for the comment. One problem I DID have was trying to get the vacuum "trio" lined up correctly with the keyway. The vacuum hoses would not go all of the way down to the switch body but I guess it was enough because it worked. I even tried heating them up with a blow dryer as it was pretty cold when I did the job. I'll probably re-visit them when it gets warmer.