I can't find where this vacuum line plugs into
 

Unbeleivable,, I spent a lot of time trying to find out where this line goes,
I don't recall unplugging it of course,, ( see the picture of the hose )

that hose is coming from the transmission and i am just lost, so if you can recognice this hose please tell me where it goes


this is the Cadillac Catera 2000 v6 3.0 engine.

It doesn't plug in the intake nor the plenum so help

you probably want to check in a Haynes shop manual or other shop manual for the catera. you can go to the libraray or buy one would be my sugestion. its hard to tell what it really is in the pics and the book most likely has a diagram of what hoses go where.

there is one hose down there which acts like a vent valve
just hangs around does the hose look like it had a clamp on it
or does it look like it was attached to anything

what about the bottom of the upper intake
close to the front there is a pipe there if i remember correctly

You know may be you just made my day,, this hose is like brand new at the end of it clearly doesn't show any sign of being plug to anything,, it doesn't have any mark on it like it had a clamp or it does not have any buldge like if it was just plug into something it would show the wear on it but again the end its just like a new hose. this hose is like a 3/8 size and the only hose of this size is the four hoses that you see on the picture and those are in the right spot since I did not disconected anyway, th other hoses are small like 1/8 or 1/4 size and there is only one on the upper intake next to the plug at the rear of the intake that comes tho the front and that is not it plus there is more by the brake booster and that is not it. So this line again is coming from the botton by the center of the transmission and the way is curves, it points to the rear by the firewall and points towards the direction of the water hoses and there is no more vacuum lines in that area. So the question is: are you sure there should be a hose that works as a vent hose??? in that area by the firewall coming from down there somewhere?

I can't see the pics very well, even enlarged...
Are you sure it is not the transmission vent hose? It would come up from around the center of the firewall, possibly off to one side or the other...

there should be one back there that is open to air

ok i remember its just loops around and hangs back there
the 4 on the plastic at the top all go to something

Ok this line is coming from way down there on top of the transmission and comes up between the firewall and the back of the engine and ir curves down and hangs there where I found it,, i am pretty sure is not one of the four hoses attached to the black plastic thing on top of the plenum but i am going to double check since i know for sure where three of them comes from but the fourth one I am going to follow it and see where its coming from, but again I follow the line in question and it goes down way down along side the top of the tranny who knows where so its not a little piece I would say its a good 3 foot long or more

down there its attached because I tried pulling and its like its attached but I didn't want to pull too hard tough, but I am pretty sure its attached

if u go to the back of the tranny on the top u should find the other end of the hose
give it a little pull and see if the other one moves
if it does
its the vent valve

Ok I put the car back togheter and all is running good,, I left the hose hanging there right behing de other 4 hoses on the plastic cover,
the car runs ok engine is smooth really smooth so there is no vacuum leaks,, a friend of a friend that has actually two cateras said that the
hose just hangs there because its a vent so all is confirmed, my mistake is that I noticed it only when I was putting everything back together and
not when I took it apart. so all is ok and thank you all for your help,
I really appreciated your concern.

I replaced HCV and found the hose like you said. I left it hung down car runs A okey.
Like you confirmed must be vent hose. Thanks for postings!

vent valve deception
 

That is the transmission vent valve hose like the other guy said. I just discovered it on my 98 Catera and it has thrown me off track just the same. It may have a tie strap holding it to the 4 vac hoses coming from the intake plenum. Good thing I read your question or I would still be looking myself. Of course my factory service manual does not help here much as it has no Vacuum diagrams in it worth looking at.
05 CTS,98 Catera, 92 Eldorado, 90 Allante, 89 Allante, 88 Eldorado, 88 Limo, 88 Cimmarron, 87 Deville

Thank you for starting this thread :)
I changed the valve cover gaskets (2000 Catera) and was getting P0411 engine error code, knew it was for the secondary air injection (AIR) system so knew I must have broke a line or put it together wrong and was getting really frustrated because I checked all the connections and hoses and didn't notice any holes, etc. I did notice a hissing up by the intake manifold and in the middle of where #2 and #3 goes in the bellow diagram; I need a vacuum diagram for a 2000 cadillac catera - JustAnswer but thought is was a hole I thought was supposed to be there because it is on a little device that I don't know what it's called but since I didn't see any extra lines thought it was a little hole on purpose to let something breath but thanks to this thread and the diagram I realized that the hose for the transmission vent I had hooked up to this line that is supposed to go to this hole I thought was supposed to be there but had broken of the plastic connector tube and didn't realize it until now that was supposed to connect to this spot.

Engine light off now and no more codes :) :) thanks to this thread and diagram