Ok , I know I must have a vacuum leak some where. First, my AC will blow great out the front vents, then for no good reason, about haft the air will divert on it's own to the defrost. Then cycle back, randomly. Sometimes it seems to be RPM related, other times speed/gear related, but I can't get it to repeat reliably.
I have also noticed that my cruise control is not setting. The light on the dash comes on, but will not set the speed.
I have replaced the vacuum lines from the manifold all the way to the battery side, and these connections seem fine. Could this be a failed check valve issue? Is there a booster, or other gizmo that may be at fault? What am I missing?
It's a vacuum leak. Have you checked the line near the T that goes into the firewall? Two of my Jeeps cracked there and caused the same problems. I couldn't see the crack until I twisted the line.
I've heard of mechanics using a smoke generator to fill up the system and then visually inspect if you see the smoke leaking out anywhere. The cigarette trick might work the same way. Take a puff, remove the brake booster vaccum line and blow the smoke into the system. I don't know if there are any check valves that might prevent from doing that though. I'm just spitballing an idea out really.
Yes, there is at least one check valve in there, in addition to the one on the booster itself.
Not sure if blowing smoke into the system would be helpful. Vacuum leaks tend to be tiny cracks (at least what I've seen). Putting enough smoke and pressure in there to see smoke coming out a crack may blow the crack out and make it worse. On the plus side, though, at least you'd be able to see it.
I remember once on my first submarine, we had a vacuum leak in one of the main condensers. Big enough to see on the gauges, but too small to hear or feel. We invited the smokers to leave the smoke pit (this was back when we were still allowed to smoke on submarines), come and light up in the area, and use their cigarettes to look for the leak. They enjoyed being able to light up in a "forbidden" area, and they quickly found the leak.
Using hairspray is another technique to finding a vacuum leak. Just spray on the lines and fittings, if the RPM's drop there is where the leak is. Just keep spraying and following the lines until you see the drop.
the only parts store I found that had these lines were @ the dealer. Anyone else find these anywhere BUT the dealer? I have taped up the cracks/hole for now.
I doubt you're going to find any place other than a dealership or online Mopar parts distributor with the preformed hard plastic vacuum lines. You could replace them with rubber vacuum hose though.
yeah I was going that route but the vacuum lines have a bit of a lip (2) to be exact on the ends to hold the lines onto the fittings, rubber ones don't. Looked pretty hokey to me....but I guess so does electrical tape to cover the holes... For now its good with the tape.
I will check our Jeep wrecker out this week and see what they have
sorry Mailman...I miscommunicated. The zip-tie would work IF I replaced with rubber. For now I just covered up the holes/cracks with electrical tape and it fixed the issue. :wink2:
Ah... gotcha...
I read that as you used rubber line and secured it to the hard line with tape because it was a lose fit.
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