mkraffert

So I developed a problem when I replaced my heater blend door. After I was done, I developed a whistle at 2400-2500 RPM. The whistle sounds like it's in the dash, in the area behind the passenger side air bag. All the vents in the dash work fine, and do what they're supposed to do. Changing the EATC control to run it through the different modes doesn't have any impact on the whistle, and all the functions work correctly. The whistle 'seems' to be louder inside the cab than under the hood.

Then, last weekend, I got real stuck in the mud. When we were pulling me out, we noticed that the front wheels weren't engaged. I removed the battery tray to see if maybe we had accidentally disconnected the vacuum canister behind the battery. Everything looks fine, but then we found this one black vacuum line that runs down to the front differential with the blue and pink vacuum hoses. (see picture) We can't find anything that looks like it is missing a vacuum line, and have no idea where it goes.

There is another black vacuum line that runs through the firewall, and that is hooked up. Where the black vacuum line goes through the firewall, the hole seems way to big for just one little vacuum tube and is oval, as if there is room for another tube next to the one that's there. Is there supposed to be another tube coming out of the firewall that hooks to this black tube?

jleaja13

I'm curious about this as well, I'm having grinding noises in my front end. Was checking the vaccum lines for leaks. And found this loner!

Anyone know?

Z7What

It goes nowhere its the vent for your front axle. You do have 4x4 correct?

Wayne

vaballa0037

That isn't the axle vent and obviously it's 4x4 you can see the solenoids right there on the firewall

4x4dave

I'm pretty confident that line goes to the front axle / diff....


But I'll post up my vac schematics. It's for a s/c conversion but it's better than nothing...Hopefully it should give you some direction.

jleaja13

Mine goes to the front diff..... I'm going to pull the battery and see if anything behind it connects to it.

Kind of wired if it vents to atmosphere. When sucking or blowing on it, it holds a vacuum. Sort of a diaphragm feeling.

jleaja13

And there is nothing behind that looks like it would remotely connect to it.

vaballa0037

Mines a 1997 so it looks a little different but mine ties in with other vacuum lines

jleaja13

Where does yours tie into.....?

vaballa0037

I just looked at mine and I don't have that line at all. I had it confused with the black one that runs through the firewall. The only 2 lines coming from my diff are the red and blue. I have a fatter black rubber like hose coming off my diff also but it looks nothing like that.