Hi everyone...I had a hose dangling under the passenger side of my 1998 Blazer, and my mechanic pulled it off where it was ripping through but wasn't able to replace it at the time. He and another mechanic argued what it goes to, (which was weird) and the owner said that it was a 4x4 vacuum hose, but the 4x4 still works, so he must be wrong. I attached some pics of the hose...I need to know what it definitely is, because I'm afraid to use the 4x4, plus I don't wanna be taken for a ride by this mechanic! There is metal inside the tip. Could it hook to a spark plug? Thanks!

 

it could be the vent for the transfercase, there are two vacuum lines going to the transfer case and one vent coming back. i think it T's in with the trans vent but not sure.

but yeah if it was from the middle of the vehicle, your 4x4 works and you havent thrown a evap code or leaked gas thats probably what it is

 

I thought the transfer case controlled the 4x4. If that's what this hose is, then how can the 4x4 still work? It was dangling from the front passenger side, under the engine.

 

the transfercase controls the front axle... kind of. basically there is a vacuum source going through one of those lines to a switch on the transfer case. when you push your button or pull the lever to lock it in 4wd something inside opens that switch and sends vacuum back to the actuator under the battery tray which pulls a cable to engage the front axle.

so if one of those vacuum hoses fell off then yeah your front axle wont engage, the transfercase will still move in 4wd and 4low just y our front tires wont be turning.

if its the "vent" line then everything will still work its just there to vent off fumes from inside the transfercase. a lot of vehicles run them to the front of the vehicle or as high as up as they can to keep water, dirt, snow, etc from getting inside the transfercase.

so double check that your front tires still spin in 4wd

 

Fascinating...how can I check for sure, since hitting the gas makes the tires move anyway!

 

In this image, in the upper left corner of the transfer case is the vent tube:



It comes out and makes a 90 degree turn toward the rear of the case. The line you have may connect there, and then to a Tee. One side of the Tee goes to the transfer case vacuum switch, which is just below the vent tube. The other side of the Tee goes to a filter that is zip tied to the transmission dipstick tube, close to the top. If that's what it is, 4WD will still work, but the risk of sucking crap into the case is very real. Just a thought.

EDIT: on second thought, that might be the vent hose with the filter missing. Check your trans dipstick tube, close to the top, is there a vacuum hose zip tied to it?

 

I'll check tomorrow!

 

I forgot to say that the engine in my truck came out of a 1999 Sonoma...we replaced it last year when the engine blew. (The catalytic converter was breaking up on the inside and shooting pieces out of the tailpipe...well, a piece got stuck and caused a backdraft into the engine, melting a valve and warping a cylinder...while I was on the highway!) I can't find a transmission dipstick no matter how hard I try. I looked online, and found that the engine I have now doesn't have a dipstick, it has...something else, which I totally just forgot, lol!

My 4wd still works fine, btw.