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Vacuum question


Bill McDuffie
11-03-2007, 06:07 PM
I have a 95 Blazer and the 4WD will not engage. I checked the vacuum actuator under the battery and I believe that it is good. The vacuum line running to it I replaced as I was hearing an air leak when I blew into the hose. I still have a leak though and have traced it to a hose that dead ends with a loose fitting cap and is wire tied to the transmission dipstick tube. Is this some kind of vacuum bleeder that is supposed to leak? Should I plug it so that it does not leak?? Any help would be much appreciated! Thanks! Please e-mail me at billm3360@comcast.net Thanks again!!:)

herkyhawki
11-05-2007, 04:45 PM
The vacuum actuator line does not connect directly to the vent cap. Do not plug the vent cap.
Did it work before, or did you inherit a problem that someone else messed up? Could you have made a mistake tracing the line back from the actator? the actuator hose should go to the "vacuum switch" in the top of the transfer case. It has three hose connected to it.
Need more info, but guess you need to change this vac sw. it is cheap, in HELP section of most parts stores.

BlackBlazOn
11-19-2007, 06:10 PM
i've got a similar problem. 4WD Hi and Lo stopped working. replaced some rotted hoses and a torn vacuum actuator (the diaphragm under the battery). that didn't solve the problem. Brought it to a dealer who ran their diagnostic junk on it. they told me it was a bad encoder motor (transfer case motor). wanted to charge me 800 bucks to replace it, so i got it from NAPA for $150 and did it myself. that fixed half the problem. now i have 4Lo, but not 4Hi. i removed the old vacuum switch on the x-fer case, and did a quick vac test, and it works fine, so i put it back in. i'm stuck though, and don't know why 4Lo works but not 4Hi. any help?

how to test the vacuum switch: just take the old one out (it is located on top of the x-fer case near the front drive shaft), connect a piece of rubber tubing on to one of the three ends. push the switch in and hold the other two ends closed. suck on the hose and see if any air escapes. repeat for other two openings.

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