Hydraulic Lines

Issues with shocks/springs, tires, steering box, stopping, etc.
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rmel
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Hydraulic Lines

Post by rmel »

Here's something to watch out for -- rub wear on the hydraulic lines.

There are three lines that run from the bottom of the air tunnel, under
and between the front diff and bottom of engine, then along the tube to
the end points of the 4x4, rear locker, and rear Brakes.

The PIX below is the Brake line, which apparently was rubbing up against the
Engine and eventually wore thin enough to burst. You can see the burst along
the lengthwise direction.
Brake-line.JPG
Brake-line.JPG (854.51 KiB) Viewed 6890 times
This is the 2'nd time this has happened :cry: The first time I ran into this problem
was with the 4x4 locker line. This was several years ago before affordable
Inspection cameras were available e.g. from Harbor Freight -- you just can't see in this
area W/O one unless you pull the engine :shock:

My hunch is someone before me did some work in this area and messed it up, so if
you have lines that have not been tampered with you might be fine -- but if you have
a camera you may want to peek in there and make sure.

Dono what's worse loosing lockers on a challenging trail or your rear brakes :?
Puller: 71' 710K 2.7L EFI aka Mozo
Follower: Sankey MK 3, 3/4 Tonne
Rescue Pinz: 73' 712MK

Driver: Ron // KO0Q
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TechMOGogy
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Re: Hydraulic Lines

Post by TechMOGogy »

Good to know
Thx for posting
72 Pathfinder | 75 710M 2.7i | 96 350GDT Worker
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GadgetPhreak
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Re: Hydraulic Lines

Post by GadgetPhreak »

Thanks for sharing, I'll be picking up a camera and doing some investigative work this weekend while swapping out my front shocks and taking care of a few other odds and ends...
King County Search & Rescue | Regional Special Vehicles Unit
1972 710M - Building up for SAR use
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sprbxr
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Re: Hydraulic Lines

Post by sprbxr »

Im fixing that exact issue on my Pinz. After fighting with a few seized fittings, I decided the best way to replace all the lines would be to remove the body from the chassis. Took a little less than 2 hrs to pull the body.
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rmel
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Re: Hydraulic Lines

Post by rmel »

I am starting to see spares for the longer Hydraulic lines becoming harder to get.
These are the lines that run from the front distribution block to the rear of the
truck for rear Brake, and locker control.

I am setting myself up to fab my own lines, here's what I have learned and recommend.

First, DO NOT toss your old tubing nuts, these are not easy to come by.

The flaring and tubing used: 6mm steel tubing, double 45 degree SAE flare. I recommend
using 6mm x .71mm Cunifer (Copper-Nickle) brake line, it is far more ductile than steel thus
easy to form, burst strength exceeds DOT requirements. Common on Porche.

You will need a very high quality flaring tool to form these seats. I have acquired a flaring
tool made in the UK, you can get one at http://www.fedhillusa.com/, you will also
need a 6mm die set. Fedhill is currently out of stock. Earl's Plumbing (Holly), has a tool set
but it is much more expensive.

Tubing nuts are: M12 x 1.0 thread, for 6mm tubing, seated for a double 45 SAE flare.
The first 2mm of the nut has a relief and that is important for proper sealing. Pictures below
show the 45 degree seat, and double flare tubing.

The one flare type that I wanted to make sure was not used here is a 37 degree double AN flare.
From the picture below you can see the nut seat is a perfect 45. From what I can tell, the metric
nuts used on the Pinz are hard to source as it is far more common for Metric tubing nuts to use a
Bubble seat not SAE -- keep the old nuts.
IMG_2854.jpg
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IMG_2855.jpg
IMG_2855.jpg (96.95 KiB) Viewed 4134 times
Puller: 71' 710K 2.7L EFI aka Mozo
Follower: Sankey MK 3, 3/4 Tonne
Rescue Pinz: 73' 712MK

Driver: Ron // KO0Q
CaptainRon
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Location: Longmont, Colorado

Re: Hydraulic Lines

Post by CaptainRon »

Hi, I have a 1974 710M. Upon removal of the locker handle plate I saw that both rubber elbows were cracked. I yanked the whole apparatus to repair and need to bleed the lines.

I am new to these trucks and I don't see 3 bleed ports below for the lockers/4x4 lines. I see two on the drive line, where is the 3rd?

Any info appreciated......thanks
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rmel
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Re: Hydraulic Lines

Post by rmel »

Slave cylinders have bleeders. But it's possible someone broke one off.
They can be pretty frail at times. Attached is a PIX showing the loc of
the bleeder -- compliments of Swiss Army Vehicles.

If one is broken off, you could either pull the Slave and replace it, or
pull it and attempt to extract the stub and replace the valve.
If the connection to the Slave is via a Banjo try bleeding through that,
but might not get all the air out of the system. Last option leave it be
and hope that that particular circuit is air free.
7103283550.jpg
7103283550.jpg (4.9 KiB) Viewed 3221 times
Puller: 71' 710K 2.7L EFI aka Mozo
Follower: Sankey MK 3, 3/4 Tonne
Rescue Pinz: 73' 712MK

Driver: Ron // KO0Q
CaptainRon
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Joined: Sat Feb 24, 2024 2:18 pm
Location: Longmont, Colorado

Re: Hydraulic Lines

Post by CaptainRon »

Thanks, I really appreciate it....I found the 3rd one I was looking for.
CaptainRon
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Location: Longmont, Colorado

Re: Hydraulic Lines

Post by CaptainRon »

So I'm pretty sure I got the locker lines bled. The lights go on when activated. If the locker/4x4 lights comes on is that a sure indicator that the system engaged? Other that four wheeling or putting it on racks to see the tires spinning...I'm not sure how to verify the system is working other that those lights.
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rmel
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Re: Hydraulic Lines

Post by rmel »

The locker light is pretty conclusive.

If you want a more positive mechanical confirmation.

For rear locker:
Lift one rear tire off the ground.
Put Tranie in neutral;
...with rear locker OFF lifted tire will spin freely
...with rear locker ON lifted tire is now locked to the rear tire on the ground.

For 4x4 locker:
Lift one front tire off the ground, rears on the ground, and Tranie doesn't matter.
...with 4x4 locker OFF lifted tire spins freely (a bit more "drag" than the rear as your spinning the large and heavy torque tube)
...with 4x4 locker ON lifted tire is locked through X-case<->rear tires

For front locker:
Lift one front tire off the ground.
Put X-case in neutral:
...with front locker OFF lifted tire spins freely.
...with front locker ON lifted tire is locked to the front tire on the ground.
Puller: 71' 710K 2.7L EFI aka Mozo
Follower: Sankey MK 3, 3/4 Tonne
Rescue Pinz: 73' 712MK

Driver: Ron // KO0Q
CaptainRon
United States of America
Posts: 27
Joined: Sat Feb 24, 2024 2:18 pm
Location: Longmont, Colorado

Re: Hydraulic Lines

Post by CaptainRon »

Thank you very much for your reply. Now I just need a bigger bottle to get this beast off the ground.... :D
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