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Should I plumb drvrs seat with comp fittings?
Our drivers seat has an air leak. While at Prevost JAX the tech (guy from Canada, David?) listened to it and said it was the lumbar control so he sold me a lumbar control replacement kit and I have set about to replace it.
Took the apron off (it was velcro’d on) and as I think George Prentice said there are two screws on front of seat cushion which when removed the seat pulls forward and everything is right in front of you.
I listened more closely to the lumbar control and it is leaking, plus one of the airlines to the seat back had come off.
The airline just below center right of the photo that has the white tie wrap is the main supply line to the lumbar control module. It looks like in the middle of the seat there is a joint in that line that uses a push on fitting; at least I didn’t have any trouble pulling it apart and pushing to back together. Should I replace this connection with a compression fitting? I’m inclined to.
When I pulled this fitting apart, I notice a small amount of black oily liquid coming out. I didn’t think that was right. Is that indicative of too much water in the lines and pressure tank back somewhere in the plumbing?
The two hoses that go from left to right in the lower part of the photo start at the lumbar control module and proceed to the left just below the Allen head bolt to a fitting which uses just simple push-on barbed fittings. Both of these airlines have the same push-on barbed fittings at the lumbar control. No clamp, just push on over the barb. One of the hoses had pulled off the barbed fitting at the control module of my seat. I’m surprised that ISRI didn’t use a clamp of some type to more tightly secure the hose on the barbs.
So three questions:
1. Should I replace the push-on fitting of the main airline with a compression fitting?
2. Should I try to put some small clamps on the airlines from lumbar control module to fittings beyond? There are at least six opportunities for clamps that I can see now.
3. What is the deal with the black oily liquid coming from the main air line?
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5 Replies
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It is no secret I’m an advocate of compression fittings so given the opportunity I would use one. But DOT push in fittings are also reliable for a long time and inside the coach where the fittings are not exposed to temperature extremes and all the dirt and crud might also be OK. I make liberal use of tie wraps to make sure a hose or wire cannot rub on something or get pinched.
The oily stuff if I had to guess is a residue that indicates at some time in the life of the coach the air system was underloved and poorly maintained and as we know moisture and oil from the compressor(s) find their way throughout the systems. I know of no other way oil could enter an accessory system.
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So are there three kinds of fitting? Push-in fittings, DOT push-in fittings, and DOT compression fittings?
I thought there were only push-in fittings and DOT compression fittings.
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Some push in fittings are OK for plumbing, but in our coaches we really shouldn’t risk air leak issues so I use DOT fittings. I won’t even buy compression fittings from the big box stores even though convenient because I want a DOT certification which makes them a little more expensive but I sleep better.
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Happy New Year to all. I have been working under the bus intermittently the last few weeks, changing all sway bar and shock bushings, all brake chambers, front upper control arm bushings, ball joint boots, and more. When get a chance will post some of the more interesting aspects of those adventures and some pit falls to avoid should you too decide to venture where monsters lie.
While it is still up on the stands and wheels off I would like to replace some of the push in airline fittings at the Norgrens and elsewhere. To that end I would like to order some bulk box(es) of the DOT brass fittings I will need. Good idea, but I am Fredericksburg, TX for the holiday and the bus is in Oklahoma.
QUESTION:
Can someone please advise the fitting sizes and about how many I will need?
From what I recall from looking around under the bus most are 1/4 tube to 1/4 npt male straight fittings. I think there may some right angle ones in there. And am I right on the male pipe thread size at 1/4 inch? I don’t recall that any I noticed are 1/8 pipe, but with my trifocal vision maybe some or all of them were 1/8, especially since at the time I looked at them I was not thinking on the lines of ordering a replacement part. I think the tubing ends are all 1/4 except for the parking brake lines which were 1/2″ tube by 3/8 pipe?
Here is one prospect 1/4 tube x 1/4 pipe male on Amazon as a starting point, still searching for some bulk 50 piece or 100 piece deal.
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Dick,
I use both DOT compression and push-in depending on application. As Jon pointed out, I stay away from standard non DOT push-in and compression.
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