Vac leak after header install: need help tracking it down.
Thread Starter
Melting Slicks
Joined: Feb 2002
Posts: 2,285
Likes: 2
From: Crooks SD
Vac leak after header install: need help tracking it down.
I just finished my install of my FLP headers and I can't get the car to stay running. My diagnosis: BIG vac leak (I can hear it). I've taken a tank of propane with a hose and tried to track it down, but no luck. Also, I even borrowed a buddy's smoker and tried to smoke it out; still no luck.
I'm not sure where it's coming from exactly, but I I think it's from the back of the intake.
I have a '99 and had a set of headers made for the new style AIR tubes. So, I pulled the intake forward and tried to install the new AIR tube (made for the newer style cars), but it's so damn difficult to get to. So, i made a new line that attaches to the header and the existing AIR tube. Problem solved, or so I thought.
I've sprayed a ton of propane on/around the intake with no luck. I know it picks up RPM's with propane, but I can't find it.
So, is there a chance I could have damaged the other end of the AIR tube when I was tweaking/bending the header end?
IS there a vac line on the lower part of the engine that I failed to find? I don't think so, but it's possible?
Could the intake just not have sealed and I should pull it and reattach? (this is odd as i'm sure the propane would have affected it if that was the case)
I'm not sure where it's coming from exactly, but I I think it's from the back of the intake.
I have a '99 and had a set of headers made for the new style AIR tubes. So, I pulled the intake forward and tried to install the new AIR tube (made for the newer style cars), but it's so damn difficult to get to. So, i made a new line that attaches to the header and the existing AIR tube. Problem solved, or so I thought.
I've sprayed a ton of propane on/around the intake with no luck. I know it picks up RPM's with propane, but I can't find it.
So, is there a chance I could have damaged the other end of the AIR tube when I was tweaking/bending the header end?
IS there a vac line on the lower part of the engine that I failed to find? I don't think so, but it's possible?
Could the intake just not have sealed and I should pull it and reattach? (this is odd as i'm sure the propane would have affected it if that was the case)
Pro
Joined: Jun 2005
Posts: 593
Likes: 1
Backside of engine has hose for PVC, AIR and then 2 hoses off back of intake, 1 for brakes and 1 is a small hose that supplies vaccum for the HVAC router to control the heater/AC doors. If you make HVAC changes and doors do not change then you know hose either is off or the hose got cut.
Intake bolts might have been over torqued or one of the 8 gaskets on bottom side is screwed up
Intake bolts might have been over torqued or one of the 8 gaskets on bottom side is screwed up
Originally Posted by Jesse_Boyer
I just finished my install of my FLP headers and I can't get the car to stay running. My diagnosis: BIG vac leak (I can hear it). I've taken a tank of propane with a hose and tried to track it down, but no luck. Also, I even borrowed a buddy's smoker and tried to smoke it out; still no luck.
I'm not sure where it's coming from exactly, but I I think it's from the back of the intake.
I have a '99 and had a set of headers made for the new style AIR tubes. So, I pulled the intake forward and tried to install the new AIR tube (made for the newer style cars), but it's so damn difficult to get to. So, i made a new line that attaches to the header and the existing AIR tube. Problem solved, or so I thought.
I've sprayed a ton of propane on/around the intake with no luck. I know it picks up RPM's with propane, but I can't find it.
So, is there a chance I could have damaged the other end of the AIR tube when I was tweaking/bending the header end?
IS there a vac line on the lower part of the engine that I failed to find? I don't think so, but it's possible?
Could the intake just not have sealed and I should pull it and reattach? (this is odd as i'm sure the propane would have affected it if that was the case)
I'm not sure where it's coming from exactly, but I I think it's from the back of the intake.
I have a '99 and had a set of headers made for the new style AIR tubes. So, I pulled the intake forward and tried to install the new AIR tube (made for the newer style cars), but it's so damn difficult to get to. So, i made a new line that attaches to the header and the existing AIR tube. Problem solved, or so I thought.
I've sprayed a ton of propane on/around the intake with no luck. I know it picks up RPM's with propane, but I can't find it.
So, is there a chance I could have damaged the other end of the AIR tube when I was tweaking/bending the header end?
IS there a vac line on the lower part of the engine that I failed to find? I don't think so, but it's possible?
Could the intake just not have sealed and I should pull it and reattach? (this is odd as i'm sure the propane would have affected it if that was the case)
Thread Starter
Melting Slicks
Joined: Feb 2002
Posts: 2,285
Likes: 2
From: Crooks SD
Originally Posted by boosted_z06
Backside of engine has hose for PVC, AIR and then 2 hoses off back of intake, 1 for brakes and 1 is a small hose that supplies vaccum for the HVAC router to control the heater/AC doors. If you make HVAC changes and doors do not change then you know hose either is off or the hose got cut.
Intake bolts might have been over torqued or one of the 8 gaskets on bottom side is screwed up
Intake bolts might have been over torqued or one of the 8 gaskets on bottom side is screwed up
Turned out to be the HVAC vac line. FYI, that's a tough one to reattach. I actually used a piece of rubber line with the appropriate hosebarb to extend and reattach. Either way, I'm back on the road
Heel & Toe
Joined: Jul 2005
Posts: 22
Likes: 0
I think I have the same HVAC problem......the vents are stuck in the defrost postition.....I took off the RF wheel and the panel to the access the vacuum hoses, but didn't see any....after putting everything back and reading more post. I understand they are in the center of the wiring harnesses. Is this correct? I'm planning on going back in this weekend to see if I can fine the leak.......
I tried the disconnect the battery overnight in order to reset the modules as suggested in another thread but it still has the same problem....
Any more insight would be greatly appreciated! I also could not find the tubes at the back of the manifold.....I looked in every nook and cranny and could not locate.....is there a panel or something that need to come off.....I saw the assembly posted but couldn't find anything that I could see that looked like that....
Thanks in advance!
97C5 Owner
I tried the disconnect the battery overnight in order to reset the modules as suggested in another thread but it still has the same problem....
Any more insight would be greatly appreciated! I also could not find the tubes at the back of the manifold.....I looked in every nook and cranny and could not locate.....is there a panel or something that need to come off.....I saw the assembly posted but couldn't find anything that I could see that looked like that....
Thanks in advance!
97C5 Owner
Thread Starter
Melting Slicks
Joined: Feb 2002
Posts: 2,285
Likes: 2
From: Crooks SD
as described above, there's a very small, hard plastic line (1/8th inch OD or so) that attaches to a plastic plug on the back of the intake. There's a larger line as well, but that's the brake booster. It appears to come straight up from right behind the block.
Pro
Joined: Jun 2005
Posts: 593
Likes: 1
The small hose that plugs into the back of intake then IS grouped into the wiring loom so you cannot see it until it exits out of loom and connects to a reserve vaccum tank that is mounted low and near right side firewall.
Then another hose goes out that tank and goes into the passenger footwell area where it connects to a router where all the HVAC doors get their vaccum from.
If that hose did not come off the back of intake then good chance battery leaked acid which flows down and eats the hose.
If you yank battery and its holding tray you then have a far better view of that area. If acid eat hose inside wire loom you'll have to just run another new hose outside of the wiring loom from intake to vaccum tank.
Then another hose goes out that tank and goes into the passenger footwell area where it connects to a router where all the HVAC doors get their vaccum from.
If that hose did not come off the back of intake then good chance battery leaked acid which flows down and eats the hose.
If you yank battery and its holding tray you then have a far better view of that area. If acid eat hose inside wire loom you'll have to just run another new hose outside of the wiring loom from intake to vaccum tank.
Originally Posted by 97C5 Owner
I think I have the same HVAC problem......the vents are stuck in the defrost postition.....I took off the RF wheel and the panel to the access the vacuum hoses, but didn't see any....after putting everything back and reading more post. I understand they are in the center of the wiring harnesses. Is this correct? I'm planning on going back in this weekend to see if I can fine the leak.......
I tried the disconnect the battery overnight in order to reset the modules as suggested in another thread but it still has the same problem....
Any more insight would be greatly appreciated! I also could not find the tubes at the back of the manifold.....I looked in every nook and cranny and could not locate.....is there a panel or something that need to come off.....I saw the assembly posted but couldn't find anything that I could see that looked like that....
Thanks in advance!
97C5 Owner
I tried the disconnect the battery overnight in order to reset the modules as suggested in another thread but it still has the same problem....
Any more insight would be greatly appreciated! I also could not find the tubes at the back of the manifold.....I looked in every nook and cranny and could not locate.....is there a panel or something that need to come off.....I saw the assembly posted but couldn't find anything that I could see that looked like that....
Thanks in advance!
97C5 Owner
