Missing vacuum line in 95-96 SE L36 hybrid - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


1992-1999 Series I L27 (1992-1994 SE,SLE, SSE) & Series II L36 (1995-1999 SE, SSE, SLE) and common problems for the Series I and II L67 (all supercharged models 92-99) Including Olds 88's, Olds LSS's and Buick Lesabres Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.

Reply
 
 
 
Thread Tools Search this Thread
Old 07-15-2014, 03:38 PM   #1
Junior Member
Thread Starter
 
Join Date: Jul 2014
Location: IL
Posts: 3
Thanked 1 Time in 1 Post
ezgrower is on a distinguished road
Default Missing vacuum line in 95-96 SE L36 hybrid

I need some help deciding how to rig a vacuum line after an engine transplant.

In 2011, the engine in my '95 SE hydrolocked (composite intake manifold fiasco) on an out-of-state trip. I had a '96 engine installed and have had relatively few problems. Recently, thought, I noticed that we weren't getting air (hot or cold) out of the dash vents, only the defrost and a little to the floor. I suspect this has been the case since we had the engine transplant -- I just didn't notice.

Apparently, this is the default condition when the vent controller has no vacuum. Sure enough, after poking around under the dash and hood for awhile, I discovered that the vacuum reservoir mounted on the firewall is missing a tube connecting it to a vacuum source. Everything from the reservoir to the vent actuators is sound.

In the '96 (the engine I'm looking at), the vacuum source on the rear side of the manifold (lower right of first picture) has two lines going from it: a large one to the vacuum brake booster, and a smaller one ("accessory" in the first vacuum diagram) to something that I don't know (third picture). In the '95 (second vacuum diagram), the vacuum source is a tree and the accessory line has a check valve in it.

Should I put a T into the accessory line with a branch going to the vacuum reservoir? Should I put a check valve in the line between the vacuum source and the reservoir?
Attached Thumbnails
Missing vacuum line in 95-96 SE L36 hybrid-1.jpg   Missing vacuum line in 95-96 SE L36 hybrid-2.jpg   Missing vacuum line in 95-96 SE L36 hybrid-3.jpg   Missing vacuum line in 95-96 SE L36 hybrid-4.jpg  
ezgrower is offline   Reply With Quote
Old 07-15-2014, 03:50 PM   #2
Member
Posts like a V-Tak
 
Join Date: Mar 2012
Location: ontario,canada
Posts: 44
Thanks: 0
Thanked 4 Times in 4 Posts
hounddog is on a distinguished road
Default

T should work, vents usually are constant vacuum so you may not need check valve. 3rd pic looks like cruise control module.
hounddog is offline   Reply With Quote
The Following User Says Thank You to hounddog For This Useful Post:
ezgrower (07-15-2014)
Old 07-15-2014, 03:58 PM   #3
Junior Member
Thread Starter
 
Join Date: Jul 2014
Location: IL
Posts: 3
Thanked 1 Time in 1 Post
ezgrower is on a distinguished road
Default

Thanks for the quick reply, hounddog. I'll go ahead and T in a branch to the reservoir and post results.
ezgrower is offline   Reply With Quote
Old 07-15-2014, 07:29 PM   #4
Senior Member

True Car Nut
 
WilliamE's Avatar
 
Join Date: Jun 2011
Location: VA
Posts: 3,087
Thanked 418 Times in 376 Posts
WilliamE has a reputation beyond reputeWilliamE has a reputation beyond reputeWilliamE has a reputation beyond reputeWilliamE has a reputation beyond reputeWilliamE has a reputation beyond reputeWilliamE has a reputation beyond reputeWilliamE has a reputation beyond reputeWilliamE has a reputation beyond reputeWilliamE has a reputation beyond reputeWilliamE has a reputation beyond reputeWilliamE has a reputation beyond repute
Default

Where is those pics is a vacuum line missing?
I looked at them and cannot see anything missing.

If you are having problems with the air not switching from defrost you should verify there is no vacuum coming into the programmer, which to do so you need to open the glove box, and push back the rubber stops so it will open up enough for you to get in behind it, then towards the body/firewall of the car you should see a vacuum hose coming in, attaching to a plastic adapter, then running into the programmer, if you disconnect the black vacuum line from the plastic adapter that leads it to the programmer you should be able to verify if it has vacuum.

See this site for some pics, and better info detailing what I am talking about.
A/C Service Tech Tip: How to redirect the cooled air in late model GM cars

If you can get some better pics showing where the missing line goes I can better advise you how to proceed.
WilliamE is offline   Reply With Quote
Old 07-16-2014, 01:11 PM   #5
Junior Member
Thread Starter
 
Join Date: Jul 2014
Location: IL
Posts: 3
Thanked 1 Time in 1 Post
ezgrower is on a distinguished road
Default

WilliamE, here'* a pic of the underside of the vacuum reservoir, unbolted from the firewall, with the tube missing from the bottom nipple. The tube on the top nipple goes through the firewall to the controller. This car has standard climate control, not electronic climate control, so it doesn't have the collapsing nipple problem described in the link you provided (it doesn't have that particular part). I wasted plenty of time digging around behind the dash before I figured that one out, but once I did, I was also able to verify that I did not have vacuum to the controller. When I worked my way back to the reservoir checking for vacuum and leaks, I discovered the missing vacuum tube.

Long story short, I spliced a tee into the accessory (narrow) tube that goes from the vacuum source on the back of the intake manifold to the cruise control servo, and branched a vacuum line with a check valve to the empty nipple on the vacuum reservoir. PROBLEM SOLVED!

My guess is that the difference in the vacuum routing between the '95 and '96 engines was enough to fool the mechanic doing the transplant into thinking he was done. There were no unused vacuum tubes coming off the engine, and the unused nipple is well hidden on the reservoir when it'* mounted. Anyways, for the cost of a tee and a foot of tubing I've got functioning dash vents and a bit of experience with vacuum systems! These boards have been very helpful, and I appreciate the effort everyone makes to help out. Thanks!
Attached Thumbnails
Missing vacuum line in 95-96 SE L36 hybrid-reservoir.jpg  
ezgrower is offline   Reply With Quote
The Following User Says Thank You to ezgrower For This Useful Post:
WilliamE (07-16-2014)
Old 07-16-2014, 09:44 PM   #6
Senior Member

True Car Nut
 
WilliamE's Avatar
 
Join Date: Jun 2011
Location: VA
Posts: 3,087
Thanked 418 Times in 376 Posts
WilliamE has a reputation beyond reputeWilliamE has a reputation beyond reputeWilliamE has a reputation beyond reputeWilliamE has a reputation beyond reputeWilliamE has a reputation beyond reputeWilliamE has a reputation beyond reputeWilliamE has a reputation beyond reputeWilliamE has a reputation beyond reputeWilliamE has a reputation beyond reputeWilliamE has a reputation beyond reputeWilliamE has a reputation beyond repute
Default

Oh wow, that does look like it was hidden well, great job finding it, and fixing it!
Also thanks for sharing, this may help others in the future that do not have electronic climate control.
WilliamE is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Missing vacuum line MHunter Buick 11 11-24-2013 02:00 PM
Help! Need missing Fuel Line Clip weathdl 1992-1999 1 02-13-2010 07:38 PM
am I missing a vacuum line? tpulliam79 1992-1999 4 05-14-2008 04:09 PM
missing vacume line ? duffer26 1992-1999 4 08-28-2005 10:58 PM
Missing Vacuum Line 95BonnieLass 1992-1999 2 09-11-2004 10:59 PM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 06:56 PM.


We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.