What is the diaphram mounted on the front axle of 2001 F150 4WD called? Who carries it and how much does it cost? I replaced vacuums line going down to it. I've found very little info on this vacuum system in general. I subscribe to Chiltons Online and they had nothing.

 

I have always seen it referred to as a vacuum motor for the center disconnect. Not sure on cost, but only place I know where to get it is Ford.

 

It is called a vacuum disconnect motor and it'll run you over $100 from Ford, the only place to get a new one. I've just been all through mine getting it to work properly.
What is yours doing/not doing and what have you checked? It's simple to remove the "motor" ( actually a vacuum diaphragm ) and check to see if it holds vacuum.
In a nutshell, the blue line should have vacuum on it when it's in 4WD and the pink line should when it's in 2WD. There's a vacuum reservoir under the right fender that the supply lines run to/from. There are two solenoids on the right cowl to control the vacuum. IF theres vacuum on the black & white supply lines to the solenoids and nothing comes out on the pink/blue lines then, of course, a solenoid is bad. The solenoids have constant 12V supplied to them and are activated by ground through the GEM. PM me if you wish and I'll send you more info.

 

so how much is a solenoid? and how hard to replace?

 

I don't know how much new ones are but I got both of these, the harness and the lines at the local U-Pull-It for $15. They just clip on the mounting bracket, maybe you can see it in the photo. The wiring and vacuum attachments just pull off. The one with the "X", the 2WD one(pink line), is what was bad on mine.

 

Great information. Does anyone know if anyone make a kit to convert from this vacuum system to a conventional lock-out hub configuration?

I figure on having this truck for 3 more years. I see this chincy vacuum hose system as recurring.

 

This thread shows the PosiLoc conversion. It enables the manual locking of the standard front axle.

https://www.f150online.com/forums/sh...d.php?t=293031

You'd have to change the complete front axle to an old straight axle to get locking HUBS. There's really not much to go wrong with the vacuum system and it's easily diagnosed and repaired. Not worth the trouble I assure you!

 

How can you tell if the vacuum motor is bad? I don't know if it is that or my center axle disconnect going bad. Any help would be nice.

 

There are the two lines that operate the diaphragm on the axle. Facing the truck, the right solenoid (pink & black lines) is activated to disconnect the axle and go back into 2WD. The left solenoid (blue & white lines) lock the axle into 4WD. ***Note that the lines are reversed on the diaphragm in this photo, thanks to FORDS incorrect vacuum diagram***


Start by removing the double lines at the solenoids on the cowl.

BOTTOM VIEW


You'll have to get a vacuum source like a Mighty-Vac hand pump and apply vacuum to the pink and blue lines, one at a time. If one leaks down you'll have to check the line, including the diaphragm, to locate the leak. If vacuum was held, reconnect the bottom half of the line "connector" (black & white lines) to the solenoids and crank the truck. Switching from 2WD to 4WD and back verify each time that there is vacuum on the top nipple of the activated solenoid. If you're in 2WD the right solenoid (pink/black) should be sucking, in 4WD the left (blue/white) should be. If these operate as described then you axle shift fork may be bad. If you're not getting vacuum when you should be, replace the solenoid. That's a quick diagnosis procedure, need more details just ask.
***NOTES***
My 2WD solenoid was bad. I got both of the solenoids and the vacuum line harness at the U-Pull-It for $15. I'd hate to think what that would have cost new.
My diaphragm has a very slow leak around the diaphram plunger shaft when in 4WD but it doesn't affect the operation. There's plenty of vacuum to keep it engaged. I don't often use 4WD and the diaphragm is over $100 so I can live with it.

 

I don't think it needs vacuum to stay engaged. That's why 2 solenoids. One to engage and one to disengage. Once it is engaged, it will stay there until vacuum is applied to disengage.

 

I would have also thought that it would operate that way. I had multiple problems with this system, including the diaphragm mount being broken off. Let me say I kind of like being bald headed since I pulled out most of my hair trying to get it right again!! It stays engaged. I've had vacuum gauges inline and held under the wiper blades so I could watch them from the drivers seat as I went round and round with my problems.

I don't know if you've had your diaphragm off or not but my shift lever works so easily that I could almost blow it from side to side. When my 2WD solenoid was bad the diaphragm would ease back towards the 4WD position. The solenoids are operated by grounds through the GEM and there's no electrical device to tell the GEM that the axle is locked/unlocked so the GEM wouldn't know to activate/deactivate the solenoids. And also, since at one point I had a leak, the line continued to suck at the point of that leak.

That's MY story and I'm stickin' to it!!

 

HI i'm haveing trouble getting the vacuum pod off. Can you help me ?? With the truck in 4x4 shold both vac lines suck ??

 

You have to remove the "E-clip" shown in this photo, not the shiny one on the plunger but the rusty one below it. That's the one that holds the diaphragm in the mounting hole. Once removed it should come out. There may be some corrosion to overcome since it is mounted in aluminum.
When in 4WD there should only be vacuum on the blue line, in 2WD only on the pink line.

 

Hey guys, i need some help with issue as well. 2000 f150 4x4 that had vacuum lines cut or corroded. I replaced the two damaged hoses with some new hoses myself, easy job BUT it didnt turn out as i had hoped.
The hoses i replaced were the pink and blue ones and now when I engage 4 WD the only tires that spin are the front and rear passenger tires, the two left tires do nothing.
I know that I put them in the correct connectors on both the pump at the bottom and the ones on the top because the wires were in place still, just had been severed.
what is interesting is that before repair, the only tire that spun was the rear LEFT (driver side ) tire but now it does not spin at all.

im perplexed..
Im very sorry if this is what they call "hijacking" a thread but it is almost very similar to my issue. If i need to make a new thread then please let me know.

Thanks Much

 

Your line repair has nothing to do with the rear axle so if the front will spin I'd say it's all operating properly. Your front differential is an open differential, meaning only one wheel will pull. What is the axle code shown on your door sticker? If it's two numbers, ie:19, it's also an open diff. If it's a letter & number, ie:h9, it's a limited slip.