1998 HVAC hoses/lines, how to route and connect?
10-03-2011, 11:17 AM
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1998 HVAC hoses/lines, how to route and connect? Hello, im in the process of putting my car together after a 243 head swap, plus parts in sig. (im running the ls1 intake until i pass smog) i purchased the car with a blown head gasket and i figured i might aswell throw some 243's on instead of the stock 806's. anyways im having some trouble with getting the vacuum hoses connected properly. the previous owner had them hooked up wrong........as far as i can tell.
ok here is the deal. i got the brake booster line hose connected at the back of the intake manifold. i cant for the life of me find the small hvac hose that connects to the other nipple on the back of the manifold. i've printed out the schematics off mitchell but they only show pictures of the 99+ vacuum hose routing. are the 98 cars the same? i can find a small hard vacuum line coming from the wiring harness that looks like the hose that is suppose to connect to the back of the intake mani. but it runs towards the back all the way down on top of the tranny and then T's off (around the tranny area) to what looks like some other vacuum hoses. i cant find the vacuum hose that is suppose to plug into the back of the manifold....... around the pcm there is a spot where three of the small vacuum lines come together, all of them seem to be in place.
are there only two vacuum hoses/lines that connect to the back of the intake manifold on 98's? i noticed on the 2000 we have here at school that the HVAC line coming from the back of the manifold T's off, one line goes to the wiring harness and the other runs toward the driver side and plugs into the A.I.R soleniod/valve. i dont need to worry about that ''T'' because 98's dont have that A.I.R soleniod/valve, correct? i just need to worry about that finding that one HVAC line that plugs into the manifold by the MAP sensor, right?
ok here is the deal. i got the brake booster line hose connected at the back of the intake manifold. i cant for the life of me find the small hvac hose that connects to the other nipple on the back of the manifold. i've printed out the schematics off mitchell but they only show pictures of the 99+ vacuum hose routing. are the 98 cars the same? i can find a small hard vacuum line coming from the wiring harness that looks like the hose that is suppose to connect to the back of the intake mani. but it runs towards the back all the way down on top of the tranny and then T's off (around the tranny area) to what looks like some other vacuum hoses. i cant find the vacuum hose that is suppose to plug into the back of the manifold....... around the pcm there is a spot where three of the small vacuum lines come together, all of them seem to be in place.
are there only two vacuum hoses/lines that connect to the back of the intake manifold on 98's? i noticed on the 2000 we have here at school that the HVAC line coming from the back of the manifold T's off, one line goes to the wiring harness and the other runs toward the driver side and plugs into the A.I.R soleniod/valve. i dont need to worry about that ''T'' because 98's dont have that A.I.R soleniod/valve, correct? i just need to worry about that finding that one HVAC line that plugs into the manifold by the MAP sensor, right?
10-03-2011, 11:46 AM
#2
in the process of my ls6 intake here, its a 98. i had brake booster map sensor and only one straight (NOT A T) vacuum line that runs to the end of my intake. its around a 3mm hard hose coming from behind the pcm. hope that helps.
EDIT: heres a pic of how mine looked like (note the rubber extension that fits over the intake nipple)
EDIT: heres a pic of how mine looked like (note the rubber extension that fits over the intake nipple)
Last edited by omarrakeen; 10-03-2011 at 12:03 PM.
10-03-2011, 01:24 PM
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awesome!!! thank you!!!!!!! i will look for it emmediately when i get home from class. hopefully its just hiding back there by the pcm or something. i already looked in that general area but i think i might remove the pcm and see if its underneath it or somthing.........i will post back in about an two hours.
10-03-2011, 05:22 PM
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i have the intake on already, but thank you for the heads up
Ok im stuck........... i cant find this HVAC vacuum line anywhere, i havnt taken out the pcm (yet) but i can see there is nothing coming from behind it. i have checked all the vacuum lines that are in the corner by the pcm (the three that split off from eachother), one goes to the firewall, one goes with the harness and goes to the front of the vehicle and the last one goes to another part of the wiring harness that leads behind the passenger cylinder head, this vacuum line splits from the harness and goes down on top of the transmission and goes into some connector and splits up into two lines. (i cant follow it from there). here's some pics of that one, i thought for sure it was the one that goes to the back of the intake but clearly it doesn't..........
Ok im stuck........... i cant find this HVAC vacuum line anywhere, i havnt taken out the pcm (yet) but i can see there is nothing coming from behind it. i have checked all the vacuum lines that are in the corner by the pcm (the three that split off from eachother), one goes to the firewall, one goes with the harness and goes to the front of the vehicle and the last one goes to another part of the wiring harness that leads behind the passenger cylinder head, this vacuum line splits from the harness and goes down on top of the transmission and goes into some connector and splits up into two lines. (i cant follow it from there). here's some pics of that one, i thought for sure it was the one that goes to the back of the intake but clearly it doesn't..........
Last edited by ggino85; 10-03-2011 at 05:27 PM.
10-03-2011, 05:53 PM
#6
hmm i guess its harder with the intake on. anyway am honestly lost here lol. i know 98 have different hvacs and i saw only one line that goes to the intake. now if am wrong am pretty much screwed 
.. heres another pic of how the 99+ hoses looks like...let me know if you found anything like that!! and btw can you start the car? if yes, start the car and turn AC on and see if everything is normal....update this back 
.. heres another pic of how the 99+ hoses looks like...let me know if you found anything like that!! and btw can you start the car? if yes, start the car and turn AC on and see if everything is normal....update this back 
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10-03-2011, 07:28 PM
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thank you for the pics......i have a good idea of what im looking for, i just dont think its even there.....the previous owner just had a short piece of vacuum hose with a bolt stuffed in the nipple on the intake manifold. i didnt notice it when i traded for the car (i traded silverado for trans am) but i did when i was taking the car apart to fix the head gasket. i figured it would be an easy fix and that one of those 3 vacuum lines in the corner by the pcm would go there, but i was wrong.....
now my next question is... does anyone know where the vacuum hose that goes to the rear of the intake manifold leads? it comes off the back of the intake manifold and goes???? maybe i can start there and find it? or re-route a new one?
edit: i read that it goes to the 3 way splitter by the pcm....
thanks again for all your help omarrakeen.... that pic of the rear of the 98 intake really calmed me down. at least i know im only missing one line and not all the ones the 99+ cars have. no unfortunately my car is not able to be started rite now , im waiting on the correct size pushrods to complete my build. they should be here in a couple of days. im thinking of just getting everything back togerther and taking care of this after i get the car smogged. i'll be putting on the ls6 intake after smog and i can really look for this vacuum line when i pull the ls1 intake off.
now my next question is... does anyone know where the vacuum hose that goes to the rear of the intake manifold leads? it comes off the back of the intake manifold and goes???? maybe i can start there and find it? or re-route a new one?
edit: i read that it goes to the 3 way splitter by the pcm....
thanks again for all your help omarrakeen.... that pic of the rear of the 98 intake really calmed me down. at least i know im only missing one line and not all the ones the 99+ cars have. no unfortunately my car is not able to be started rite now , im waiting on the correct size pushrods to complete my build. they should be here in a couple of days. im thinking of just getting everything back togerther and taking care of this after i get the car smogged. i'll be putting on the ls6 intake after smog and i can really look for this vacuum line when i pull the ls1 intake off.
Last edited by ggino85; 10-03-2011 at 09:27 PM.
mayebe someone could chime in and point you to the directions they delete hvac all the time over here.
10-04-2011, 08:17 PM
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alright so my buddy came by today and he has a 98 camaro z28 (bone stock) so i took a look at his vacuum lines and one of three lines that come together by the pcm does seem to lead to the rear of the manifold. there is no vacuum line leading down to the transmission area from the pcm, that i can see on his car. im thinking of just cutting the vacuum line and T'ing it off so that one end goes to the rear of the manifold and the other can stay connected to whatever it is connected to down by the tranny. apparantly from what i have read online, i just need to get vacuum connected to the line coming from the firewall, it seems to not be too important how you hook up the vacuum, as long as you get vacuum from the rear of the intake to the lines in the corner by pcm.
10-05-2011, 07:04 AM
#11
alright so my buddy came by today and he has a 98 camaro z28 (bone stock) so i took a look at his vacuum lines and one of three lines that come together by the pcm does seem to lead to the rear of the manifold. there is no vacuum line leading down to the transmission area from the pcm, that i can see on his car. im thinking of just cutting the vacuum line and T'ing it off so that one end goes to the rear of the manifold and the other can stay connected to whatever it is connected to down by the tranny. apparantly from what i have read online, i just need to get vacuum connected to the line coming from the firewall, it seems to not be too important how you hook up the vacuum, as long as you get vacuum from the rear of the intake to the lines in the corner by pcm.
so i didnt miss anything right? and yes you are right, u just need to hook a vacuum to it whatever configuration it is.
