Hi,

4wd not been engaging, after much searching, under the battery I found a daiaphram/ bellow type contraption (i'm an surgeon not a mechanic). I am presuming this is the accuator for the 4wd transmission engagement.

I also found down here a hose, about half an inch thick that sucks (literally not metaphorically) when the engines on. i am presuming this is the vaccum hose and its unattachedness is the reason I have no 4wd.

The problem is I don't know where it is suppose to attach to.

Any pictures or description would be very hepful.

Gordon

 

The front axle engagement actuator is located under the battery. The vacuum lines that transfer engine vacuum are typically 1/8" or 5/16" vacuum hoses which are much smaller than 1/2".

That 1/2" hose is the intake hose for the AIR system (AIR = air injection reaction). It is the hose that is along the passenger side of the radiator fan shroud about halfway up from the bottom of the radiator. It has nothing to do with the 4wd system and is meant to be disconnected like that.

With that said, we really need to know what it is you are driving and what it has in it for a 4wd system. Please list your year and # of 4wd switch buttons in the dash.

Also, you may want to run a few searches. I know I have posted vacuum diagrams for various vehicles in the past as well as others on the forum so they shouldn't be too hard to find.

 

its a 2000 Blazer LT, the 4wd is a auto, 2hi, 4hi, 4lo switch.

the hose may be a bit smaller than 1/2 inch, it goes from that front fender well up towards the top back of the engine where it joins to a different hose which then goes on to the passenger side just behind the CPU.

(its a RHD so most of the engine is reversed to a LHD.)

 

Are you talking about the inside diameter of the line or the outside diameter of the line...?

As far as the vacuum lines for the 4wd go, they should run from the engine to the check valve which is also a 't'. There will be another 't' after. The three ports now will have one going to the HVAC system (into the firewall), another going to the vacuum solenoid on the firewall, then the other vacuum reservoir which is located inside the left (driver on LHD) side fender. The other side of the vacuum solenoid will then run to the vacuum actuator under the battery.

 

The outside diameter, it does come from and pass past the firewall via two T junctions and was lying near the diaphram. Looking into the end of the hose looks like it would fit onto a small male end.

 

Its now attached to the diaphram and its now reacting to the switches on the dash. Thw 4wd is still not engaging to as everything is working up to that point I presume the failure is under the car at the front axle engagement point.

 

Look inside one of your fenders for the vacuum reservoir.