Shift on the fly not working
Butt-Head
Joined: Apr 2004
Posts: 9,432
Likes: 2,919
From: Reed Point, MT
Here's a question:
Was the engine running or the key in "run" position when you took out the rear driveshaft? If not, then the vacuum pump was not running and your hubs disengaged themselves. Your hubs may work, but if the vacuum supply was depleted from the reservoir, then you had no vacuum to hold the hubs in "lock" position.
Was the engine running or the key in "run" position when you took out the rear driveshaft? If not, then the vacuum pump was not running and your hubs disengaged themselves. Your hubs may work, but if the vacuum supply was depleted from the reservoir, then you had no vacuum to hold the hubs in "lock" position.
Elder User
Joined: May 2007
Posts: 752
Likes: 0
From: New Orleans
at the risk of sounding like a jerk. always chalk the wheels when working on the drive system. also if you look where the axel mounts into the hub behind the wheel and that boot is ripped it won't hold the vacuum it need to lock the hubs and water will get in.
Ryder
Ryder
Thread Starter
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Senior User
Joined: Apr 2007
Posts: 302
Likes: 0
From: Backwoods Near Pittsburgh
i know i should have chalked them, but when i put it in 4x4 before the removal i thought it would hold it back never thought about the shift on the fly failing.
Still though i know i should have chalked them i was just in a hurry
Still though i know i should have chalked them i was just in a hurry
Senior User
Joined: Mar 2007
Posts: 473
Likes: 3
From: Issaquah, WA
Above the right front fender well is a little vacuum pump. It routes to a vacuum canister which routes to the a Pulse Vacuum Hublock (PVH)Solenoid (attached to the side wall above the fender) that controls vac to the hubs. First assuming your vacuum pump is working (unplug the hose going to the cansiter and it should turn on), makes sure the PVH is working by unplugging the hose that goes to the hubs and checking for suction. It will pull vacuum for 20-30 seconds when the auto hub switch is activated. If not, you need a new PVH, $65. If you have vacuum at the PVH, then verirify the tubes between the PVH and the hubs are tight. Inspect the vacuum lines at each wheel where they connect to the hub lock nipple. (Inside the each wheel well you'll see the hoses feed from the engine compartment to the axle/nipple.) If they look good, unplug them one and check that it has, and can hhold, vacuum. If not, you have a bad vac line somewhere. If so, then you need to pull a vacuum on each hub, find out which one is leaking and repair from there. With any luck you just have a rotted hose at a nipple...
Good luck.
Good luck.
Junior User
Joined: Sep 2006
Posts: 65
Likes: 0
From: Canton,MI
No worky shift on the fly
Try this site for you line problems.
http://http://www.dieselsite.com/ind...ROD&ProdID=348
I have a V10 and I am looking at using these for my SD. My rubber lines were cracked and the hub nipple is rusted on both hubs. This site is great for help in diagnosing problems.
http://http://www.dieselsite.com/ind...ROD&ProdID=348
I have a V10 and I am looking at using these for my SD. My rubber lines were cracked and the hub nipple is rusted on both hubs. This site is great for help in diagnosing problems.
Logistics Pro
Joined: Mar 2002
Posts: 3,881
Likes: 84
From: Wake Forest, NC
Originally Posted by cleatus12r
Here's a question:
Was the engine running or the key in "run" position when you took out the rear driveshaft? If not, then the vacuum pump was not running and your hubs disengaged themselves. Your hubs may work, but if the vacuum supply was depleted from the reservoir, then you had no vacuum to hold the hubs in "lock" position.
Was the engine running or the key in "run" position when you took out the rear driveshaft? If not, then the vacuum pump was not running and your hubs disengaged themselves. Your hubs may work, but if the vacuum supply was depleted from the reservoir, then you had no vacuum to hold the hubs in "lock" position.
Logistics Pro
Joined: Mar 2002
Posts: 3,881
Likes: 84
From: Wake Forest, NC
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