replaced old t-case vaccum switch today with new one, also replaced a/c head unit with one off ebay. I figured that if my original unit had fluid damage I could go ahead and replace it all at one time. Well, on my way home from work tonight i'm running 75mph or so down the interstate I hear an all to common sound I used to get from my 98 4*4 blazer, the sound of "zzzzzzzzzzzzzZZZZZZZZZZZZZZZZZZZZZZZ", that is the sound of metal gears in my front end touching but not engaging. The only thing I could do was to slow down to a crawl and put my crew in 4 hi. Once locked it, sound is gone, everything sounds normal. So I drive a few miles after I reingage back into 2 hi, and not soon after I get above about 65 HERE WE GO AGAIN!! . So I repeat the previous process. In seven months I have never had this problem until today when I changed out the switch and head unit. How could cable actuator pull partial vacuum causeing the front diff. gears to touch but not fully engage, especially when the t- case is in 2hi. The transfer case works great though. WHAT HAVE I DONE? I had this similar prob with my blazer but never knew what it was so I just pulled the 4*4 fuse and totally disengaged the t-case and all. However, because of you'll kind, intelligent crewers I now have a general understanding of how this vacuum sysem works. I need suggestions quick guys!!
Edited title-HJ
[size=75]modified air box, aluminum skid shields, custom sirius radio, 15%tint, powdercoated diamond bed rails/toolbox, mild t-bar crank, Reese class III receiver hitch, 1 3/8 core high capacity radiator[/size]
I would start by disconnecting the vacuum hose off the actuator then start the truck to see if there is a vacuum on the hose. If so, I would think you have a bad switch. If there is no vacuum on the hose plug the end with a small bolt or screw then take the truck for a ride and see if the sound is still there. If it is I would change the fluid in the front diff. There is a fork in the diff that moves a gear to lock it in drive. This may be stuck or your cable may be dry and sticking. They do sell a cable lube that can free that up also.
[size=75]2001 S-10 Crew , A.R.E Cap, Limo tint windows, Halogen Back up lights. Bilstein Shocks, 1.5 Rear Spacers, Summit Rear Diff Cover Clear Bumper Lights, Carbon Altezza Tail Lights, Billet Grill. SS Step Bars. GM full front bra. ,,, GM Quote concerning the gurgling heater core " They all sound like that"[/size]
Double check to make sure you have the vacuum lines properly clocked at the attachment to the new switch.
You should only be able to get them on in one position with that pin. Also check to make sure the switch is fully seated and not cross threaded.
The next check will need to be the actuator. Pull the battery and tray to expose the actuator. Look for interference or a "tight" cable. This could be from failure to relocate the actuator after a bodylift, or corrosion/ oxidation in the cable. Either could cause it to not fully release.
"Speed doesn't kill, suddenly becoming stationary does." - Richard Hammond
"Speed is just a matter of Money - How fast do YOU want to go?"-Mechanic from Mad Max-
If at first you don't succeed - Don't take up Skydiving! - ThunderIIKE7CSK
You were right henry, I got underneath this morning after I turned my key to access. and heard a hiss from unerneath. I removed the t=switch and reinstalled. I guess one of the lines wasn't connected completely. Drove it home on the interstate and NO PROBLEMS. I''ll keep my fingers crossed though. Thanks for the quick responses to all my posts everyone!!
[size=75]modified air box, aluminum skid shields, custom sirius radio, 15%tint, powdercoated diamond bed rails/toolbox, mild t-bar crank, Reese class III receiver hitch, 1 3/8 core high capacity radiator[/size]
T-bone02 wrote:...I got underneath this morning after I turned my key to access. and heard a hiss from unerneath. I removed the t=switch and reinstalled. I guess one of the lines wasn't connected completely. Drove it home on the interstate and NO PROBLEMS.
Nice job! Glad you solved your problem!
"Speed doesn't kill, suddenly becoming stationary does." - Richard Hammond
"Speed is just a matter of Money - How fast do YOU want to go?"-Mechanic from Mad Max-
If at first you don't succeed - Don't take up Skydiving! - ThunderIIKE7CSK
. So I repeat the previous process. In seven months I have never had this problem until today when I changed out the switch and head unit. How could cable actuator pull partial vacuum causeing the front diff. gears to touch but not fully engage, especially when the t- case is in 2hi. The transfer case works great though. WHAT HAVE I DONE? I had this similar prob with my blazer but never knew what it was so I just pulled the 4*4 fuse and totally disengaged the t-case and all. However, because of you'll kind, intelligent crewers I now have a general understanding of how this vacuum sysem works. I need suggestions quick guys!!
Glad you solved your problem!