Vacuum Leak - Part II

tomsm · 05-09-2010, 09:20 AM

Like most owners of Winnie/Itasca DPs that are a few years old, I corrected the leaking green vacuum line several years ago. Now, I have a new leak.

I double checked the green line and that's not the problem...

I accessed the back of the dash A/C controls by removing the dash cowling. All the vacuum hoses that go to the back of the control module are well attached and not split. They are very flexible and appear like brand new. I tried pinching off each of the hoses and found that the pump shuts off when I pinch the blue hose. None of the others affect it.

I used to have some documentation, other than the users manual, but can't find it now. Does anyone know what the blue vacuum line is used for? It disappears down into the dash and I can't find it anywhere "out front". Apparently it is activating a damper down inside the dash somewhere. I've never tried to access the inside of the dash. Anybody been there, done that?

tomsm · 05-29-2010, 09:29 AM

Guess I'm the first to have a 2nd vacuum leak. Same symptoms as before - vacuum pump runs continuously when you set the dash air/heater control to "Off".

I had identified the new culprit as being the blue vacuum line (read post #1), but didn't think it appeared under the "hood" like the green one did. Actually, I was looking right at it and thinking it was a blue electrical wire. It appears out front in the same area as the green line and goes to an actuator that's down and left from the hood opening. I could touch the actuator from out front, but couldn't pull the hose off. Was able to reach it from underneath and pull off the blue line.

What I found was that the blue line was disintegrating from about 6" to 12" from the actuator. It was full of tiny pin holes. I cut off the lower 2 feet of it and headed over to the NAPA store. They found a size of windshield washer hose that would slide tightly over the blue line and also connect tightly to the actuator. About $1.60 for 2 feet of it and problem solved!

Short version - if you have already experienced the split in the green vacuum line connector at the hot water modulator and you get another vacuum leak, check out the blue line that comes through the firewall at the same place the green one comes through.

Gary CA · 05-29-2010, 11:49 AM

Tom: Thanks for all the info, I'll go check the condition of mine right now.

McDuff · 05-29-2010, 05:06 PM

Tom, thanks for doing the exploration. We just did the green hose fix a few days ago, and it still is acting up "a little". I now have another place to look.

SCVJeff · 05-29-2010, 07:54 PM

So it's the colored line itself coming apart and not the adapter hose? That could be interesting up behind the dash assembly since I think that it's glued into a one-piece manifold along with the other colored hoses. I wouldn't have guessed there were adapters that small

tomsm · 05-30-2010, 08:05 AM

Jeff - yes, it's the blue hose itself that is disintegrating. The part of the hose behind the dash is pristine, it's the last foot or so before the actuator "out front" that is leaking. I guess you're thinking that it would be a problem to replace the whole length of the hose and I agree. That's why I just replaced the last 2 feet of the blue hose with windshield washer hose. Maybe not too elegant, but it works fine. I zip tied the junction of the old and new hose and attached both to nearby wire bundles so it can't work it's way loose...

Wayne M · 05-30-2010, 01:16 PM

Tom,
Any chance of a picture or two?

tomsm · 05-30-2010, 04:49 PM

Wayne - sorry, but my 2 year old camera has decided to stop working. When I get it repaired/replaced, I'll try to remember to add pictures here...

Lt46 · 05-30-2010, 06:56 PM

Did the same repair on the green hose. Windshield washer hose over the green. Only difference was I slathered the green with some RTV silicone to seal that transition. Did it last year and no issues to date.

JimO · 06-02-2010, 10:26 PM

I have the same problem when the control is off. I have a UFO rear engine gas chassis. Should I be looking for a green and blue hose?

Wayne M · 06-02-2010, 11:12 PM

Tom,
They make cameras now that take colored photographs, even the newer digital models.

I'll patiently wait for your post.

tomsm · 06-03-2010, 08:19 AM

Wayne - yep, it was one of those new, modern, color, digital cameras that failed..

Since I don't know when I'll get pix in here, here's a link to some pictures that vicsryd added to a previous post. They're as good or better than anything I could take. In the first picture, notice the blue line going off to the left wrapped around a wire bundle. The second picture shows the actuator with the blue line attached. The last 6-12 inches of the blue line is what was falling apart. Sorry, I've already thrown away the rotted blue line, but it doesn't take a rocket scientist to see the problem. If the blue color is faded away and the jacket is crumbling, you'll easily see it.

There are also some good pix from SCVJeff in that link.

tomsm · 06-03-2010, 08:25 AM

JimO - not real sure if this applies to you or not. Usually gassers use manifold vacuum for the ac/heat system. Since your engine is at the other end, maybe they used a vacuum pump on yours too. If you hear a continuous buzzing from up front when you're in "OFF" or "MAX AC" modes and goes away if you change to "Vent" mode, that probably is a vacuum pump with a leaking system. Check the link in the post above for pictures of what to look for...