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Old 01-29-2020, 08:34 PM
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how do high pressure lines seal?

I just did a post about a leaking power steering line leak.
My son and his friend lost the seal that came with the new pump.
They substituted a rubber o-ring. It didnt work.

I started wondering about what is actually happening on a flanged metal tube
with a nut on it.

This line was leaking around the threads.
My guess is that the threads have nothing to do with the sealing, besides providing the tightness.

How do those flanges seal? Does the metal tube make contact with the metal housing? ? Or does the plastic, or rubber, o ring make the seal between the tube and whatever housing its going to?

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Old 01-29-2020, 09:17 PM
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The thing has a crush sleeve of some sort. The material is going to depend on the application. But generally it is rubber, nylon, or copper.

Just like with injectiors or other seals there is usually a recess the seal sits in and you need to be careful not to sheer the seal during the install. A bit of power steering fuild does the trick. Also take note on torque and have clean threads.
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Old 01-29-2020, 11:06 PM
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If this is the fitting you are talking about, you are correct that the threads are not the seal the O-ring compresses against a seat in the female fitting and the nut forces the bead on the tube against the O-ring, which forces the O-ring against the seat. It is the compression of this O-ring against the seat and tube that makes the seal. If it is leaking, first, do not try to reuse these O-rings, replace them. Second, it is very easy to nick the O-ring when assembling the fitting. Any damage, however slight, will prevent the O-ring from sealing.

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Old 01-30-2020, 12:37 AM
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Not to mention, not all O rings are created equal.

Other systems may use a flare fitting at these pressures it would be a double flare where a wider than usual flare is rebent into itself to double the thickness.

Some systems use a crush sleeve that is compressed around a tube as the screw fitting is tightened into the receiving fitting, these can be brass, copper or some sort of engineering plastic.

Unlike house plumbing the threads do not stop anything they are only there to put force onto the sealing gadgets, those, whatever their design is, do the leak stoppage pressure containment.

Hoses that leak usually do so inside the crimp that secures the hose to its fitting. In this case there is nothing short of replacement that solves the problem.


Bogie
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Old 01-30-2020, 01:45 AM
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If you have a place locally that makes hydraulic lines they usually have a shelf with seals.
Some auto parts chains like parts plus or bumper2bumper maybe some carquest make lines but it is hit and miss depending on the area.

They can supply new fittings if your rack/box ones are stripped or the fitting is just rounded and ugly.
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Old 01-30-2020, 10:25 AM
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I figured that how they worked. This one has a cone shaped flange. Im starting to think the kids damaged the flange. Its hard to see it, but it feels rough on the end.

The line in the picture here from Joe, to me , looks like a superior design than the one i'm working with.
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Old 01-30-2020, 10:32 AM
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Quote:
Originally Posted by briansansone View Post
I figured that how they worked. This one has a cone shaped flange. Im starting to think the kids damaged the flange. Its hard to see it, but it feels rough on the end.

The line in the picture here from Joe, to me , looks like a superior design than the one i'm working with.
A photo of yours would help. Are you saying you have an inverted flare fitting like the one on the left end of this adapter?

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Old 01-30-2020, 06:32 PM
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Quote:
Originally Posted by joe_padavano View Post
A photo of yours would help. Are you saying you have an inverted flare fitting like the one on the left end of this adapter?

No, its cone shaped, with the smaller diameter at the pump. if there is a ridge, its hidden behind the nut. I cant turn the line to look at it head on. It looks different than any other pressure line I have seen. The pump side has a valve, like a shrader valve. and a hole in the threaded area ? It just doesnt look like it mates together well. It looks like the whole set up is prone to leaking, but I never had a problem before. We got a o-ring rebuild kit......it didnt have the right one.
I'm about to break out the epoxy and be done with it.
When I put the rack in years ago, I noticed it was broken at the pressure line connection, AFTER it was all in. So I epoxy'ed that in. It hasnt leaked in years.
Id like to fix the connection correctly, but getting the seal has been an issue.
Ill just know that if it ever has a problem, Ill have to do the pump, the lines, and the rack.
Ouch

Last edited by briansansone; 01-30-2020 at 06:37 PM.
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Old 01-30-2020, 06:48 PM
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I just found a manual on line that read " using the special tool, install the new seal"

THere is also a schematic of the end of a line that looks very very similar to what I have. There is a drawing of a "teflon seal" there on the page too.

It says its the connection of the line to the cooler " but orthers are similar", is how it reads.

Am I missing a teflon seal that not even the dealership new I am supposed to have?
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Old 01-30-2020, 07:09 PM
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I got it.
It seals at the threaded nut, with a teflon ring. There is no o ring on the line, or seated in the pump.

Live and learn.

I have been moving from chevys to fords. Learning some differences.
The Windstar is sentimental to my wife, which is why I resurrected it,
and I inherited a 1990 f150. I love it. I just need to start picking up on Ford design.
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