Hello,

I bought a 2002 Blazer with 4wd for my mother in law to have a car. I limped it home, and it wouldn’t start. I put a new cap and rotor on it and now it kicks over. I used to build small blocks back in the day with my brother, and I could tell when it got going it had some vacuum leaks. The PCV valve was a little rattly. I started pining around and found this stuff. All the ones I did were pre-vortec.

it looks like it splits off and goes to a hard line that goes into the dash maybe? It tees off to something that hits the PCV, and then it goes over the distributor and dives down towards the transmission. I didn’t think these 4L60E trannies used vacuum, but it started getting dark and I couldn’t trace it down. Most of this vac line is crumbly and soft.





What is this stuff?

thanks for the help, I want to get her this car going and she’s pretty excited about it. It only has 98k miles and it’s fairly clean.

 

Here is another picture of it…

 

Those are the vacuum lines that supply vacuum to the front axle engagement actuator and to the HVAC system. It is not uncommon for those to dry-rot and fail.

In your first post, you are holding a one-way valve with a built-in tee. In the second post, you are holding the vacuum line that goes to the front axle actuator.

I've been maintaining a thread (see my signature) for how to replace these hoses for Blazers that have the 4-button (Auto 4WD) transfer case.

One of the trickier aspects of this repair is getting the hose back onto the vacuum reservoir that is tucked into the fender. You'll see pictures in that thread I mentioned.

 

thanks for the help! I’m new to this forum thing and I don’t see your signature on the post. I’m having to do this posting from my iPhone. Somebody tried to steal my bag at DFW airport, and i had to tackle the dude. It had my laptop in it and it broke.

is there a way that I could see that link and check it out? I have pretty small hands and it’s been helpful in the past working on cars to get things in the right place. I’ve done a lot of things for professional mechanics because my “little baby hands fit in there”. Haha.

Thanks again for the help.

 

Oh man, that sucks about your laptop. The phone app version for the forum defaults to no signatures.

But here's the link:
https://blazerforum.com/forum/2nd-ge...replace-95425/

Good luck and be sure to report back.

 

BTW, where in Vermont do you live? Northeast Kingdom? I lived in West Fairlee for a few years little over 20 years ago.

 

We are up in St. Albans, western side of the state.

I read through that post and it seemed to be talking about a “4 button 4x4”. This one has three buttons on it. Does it make a difference with the diagram?

i appreciate the help. My mother in law has been vacuuming it out and she is eager to see this little blazer get on the road.

 

The 3 and four button transfer cases have a bit different vacuum line configuration.

However, the lines that rot are the same ones that you found.

The difference is that the 4-button ones have a single vacuum line that goes to a solenoid mounted on the firewall the 3-button ones don't have. The 3-button ones also have a bundle of three hoses that go to the transfer case. I don't think I've ever heard of these three hoses rotting.

What yoU will want to replace are the hoses that are connected to the tee.

I hope that helps.

 

Sooner or later I'm going to get this diagram finished (still more details I need to add) but this is the vacuum line setup for the 3-button system. The color lines are in the dash for the HVAC controls and not what your concerned about. You concern is the black lines. There might be some slight routing differences in the engine bay.

EDIT: There is one short black line not shown. It's a vent line from the transmission that Tees into the transfer case switch vent line (the line that terminates on the right side of the diagram into what looks similar to a Chess "Pawn" in the diagram).