4X4 Vacuum Leak?
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Senior User
Joined: Aug 2004
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From: Yacolt, Washington
4X4 Vacuum Leak?
The last time I had to use 4 wheel drive with the hubs in auto it would'nt go into 4, I locked the hubs and no problems.
I've noticed the vacuum pump runs every time on start ups while waiting for the glow plug light to go out.
I seem to remember that a vac hose to the hubs sometimes develops a leak?
Any ideas where I should look? Also I was wondering if the same pump also supplies vac to the brakes?
Thanks, Walt
I've noticed the vacuum pump runs every time on start ups while waiting for the glow plug light to go out.
I seem to remember that a vac hose to the hubs sometimes develops a leak?
Any ideas where I should look? Also I was wondering if the same pump also supplies vac to the brakes?
Thanks, Walt
Postmaster
Joined: Sep 2008
Posts: 3,220
Likes: 0
From: VA
Could be a number of this causing the vacuum leak.
Yellow o-ring missing/failed on hub
Knuckle seal failed
Vacuum lines themselves failing
Vacuum solenoid
Unplugged line somewhere
What I did to diagnose my problem was to use about 10 feet of spare tubing and hooked it to my drivers side hub directly to the line coming from the solenoid. Engaged ESOF after I gave the pump time to shutoff. Check the u joints on that side and see if they turn or not. If they dont then that hub is good. Do the other side as well. Once you do those and they lock into 4x4 then you can cross out the hubs and solenoid. Chances are its the lines.
Mine was a failed knuckle seal, no o-ring at all, and improper installation of a thrust washer...
I dont know much about the vac system being used for anything else so I cant answer that question...
Yellow o-ring missing/failed on hub
Knuckle seal failed
Vacuum lines themselves failing
Vacuum solenoid
Unplugged line somewhere
What I did to diagnose my problem was to use about 10 feet of spare tubing and hooked it to my drivers side hub directly to the line coming from the solenoid. Engaged ESOF after I gave the pump time to shutoff. Check the u joints on that side and see if they turn or not. If they dont then that hub is good. Do the other side as well. Once you do those and they lock into 4x4 then you can cross out the hubs and solenoid. Chances are its the lines.
Mine was a failed knuckle seal, no o-ring at all, and improper installation of a thrust washer...
I dont know much about the vac system being used for anything else so I cant answer that question...
Hotshot
Joined: Jan 2002
Posts: 17,988
Likes: 207
From: La La Land
Thus, if you blow a power steering hose, you not only lose the power in power steering, but you lose the assistance in your brake system, too.
You don't lose steering or brakes, but YOU are then the one supplying the "power" to make them operate.
The vacuum pump's there to supply vacuum to the ESOF system and the heater/air conditioning controls.
The cheapest way to start troubleshooting this is to simply replace the vacuum hoses to the front hubs, as they're the most likely culprits.
It's simple. Take off each front wheel for access. Everything will be right in front of you.
I replaced each of my wheel-well vacuum hoses with 22-1/2 inches of 3/16" (4.8mm) SAE 30R7 fuel hose each side. Secured the ends with a tie-wrap.
It may last longer than OEM, and it fits perfectly.
Pop
Laughing Gas
Joined: Mar 2008
Posts: 967
Likes: 7
From: coquitlam,BC
The last time I had to use 4 wheel drive with the hubs in auto it would'nt go into 4, I locked the hubs and no problems.
I've noticed the vacuum pump runs every time on start ups while waiting for the glow plug light to go out.
I seem to remember that a vac hose to the hubs sometimes develops a leak?
Any ideas where I should look? Also I was wondering if the same pump also supplies vac to the brakes?
Thanks, Walt
I've noticed the vacuum pump runs every time on start ups while waiting for the glow plug light to go out.
I seem to remember that a vac hose to the hubs sometimes develops a leak?
Any ideas where I should look? Also I was wondering if the same pump also supplies vac to the brakes?
Thanks, Walt
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