Hi guys, ive been trying to get some answers about the issue with my 02 Blazer. I bought it last year with 75k miles on it, and while everything works, and is in good general repair, the only two things that were inop when i got it was the vent selector, and the 4x4 was slow to engage.

Now, I have had a few S10 trucks and 2 older blazers in the past, so I am no stranger to the issues with the vacuum system. The problem is that ive not had these kinds of issues before. Ive been dealing with the problems as my AC works and I'm getting air from my dash vents, but today after spending some time washing and detailing it, i noticed that the vacuum line that sits between the fender reservoir and the check valve is "sweating" oil. It feels like a scilicone hose when I handle it.

The oil i see seems to be either engine oil or trans fluid, but I cant really tell. I had previously replaced this line because it was brittle. I'm guessing i have a bad check valve somewhere.

Is the check valve by the fender the ONLY check valve, or are there more? Is there a diagram that shows ALL the vacuum lines and where they go available?

Thanks!

 

Take the vacuum lines off the top drivers side of the transfer case and see if it has oil in it. Its 3 vacuum lines together just inboard of the transfer case selection motor.
The vacuum switch on the transfer case is what controls the front axle disconnect and i have seen a couple of them leak and allow fluid from the transfer case into the vacuum lines. This can also cause issues with the front axle not engaging.

 

GMC Sonoma & Chevy S-10 Transfer Case Vacuum Switch

Revised Transfercase Switch

 

Awesome! Thank guys! I am gonna order that switch now. Hopefully this will work.

By the way, has anyone ever thought about replacing the vacuum hoses with rigid steel tubing? Feasible? Waste of time?