Hey guys,

I didn't want to start a new thread with as many as there are already out there, but I didn't really think it fit in any of the others that I saw, so I decided to regardless. Here's the question...

Can someone (or a few people) describe the performance of their vacuum pump and system? In other words, We all know a complete vacuum is very hard to achieve, but I'm wondering how inefficient my system is.

I'm not by my truck, but from what I remember it was something like this to give you reference for what I'm after...

1. Key turned to on.
2. Pump runs for about 45 seconds before shutting off.
3. Pump is off and vacuum is held for 30 seconds.
4. Then pump kicks on for about 20 seconds.
5. Repeat steps 3 and 4 over and over again.

That's my best guess, and I'll verify when I get home, but is this pretty inefficient compared to what you guys are seeing. I don't want to put unnecessary wear on the pump ... within reason.

Thanks.

 

You have a vacuum leak somewhere OR the pump is failing.

 

But how bad is it leaking?

Can you give me a hold time on yours before the pump kicks back on?

Thanks.

 

Mine hold for about 6 - 8 hours, maybe longer.

 

Once my vacuum charges up, I never hear it again - but the engine would be running by the time it did run, drowning out the noise. I can tell you I've spent a lot of time KOEO with AE, and the vacuum never re-triggered once it shut off.

You have a vacuum leak, and it's very likely near the front wheels. All my leaks were hoses near the wheel, and the actual ESOF control valve on the passenger fender.

 

I just replaced both hoses in the wheel-wells (see... https://www.ford-trucks.com/forums/1...l#post15000670), and I can't hear it leaking anywhere else.

Any other suggestions?

How can it be leaking from the ESOF control valve? I know the one you're talking about, but it's all electrical, no?

Thanks again.

 

I just know I isolated every component on my ESOF system and hooked up a Mity Vac with a gauge. The control valve had a bad case of lackin' suck.

 

A vacuum leak near the wheels would be after the vacuum solenoid switch... there is only a vacuum past the switch once the switch on the dash is flipped.

I had a leaky solenoid switch, vacuum pump, and a rubber t-fitting.

If you (the Op) are losing vacuum without the 4x4 selector selected to select 4x4 operation then focus your leak detection dectector at the solenoid backward.

Past the solenoid(leak symptoms observed with the 4x4 selector selected to select 4x4 operation) the most likely culprits for leakage are : knuckle vacuum seal(most expensive seal on the truck), hub unit seal(the yellow one that fits in the ring groove cut on the tail end of the hub unit) or the locking hub oring(black oring in the groove on the locking hub).

 

It's pretty well covered above. There are only two vacuum branches, one reservoir, and some tubing.

Remove the ESOF and put a Vacuum pump on the tubing and draw 15 in. Hg. and let it sit for 15 minutes or so and re-check the gauge.

Remove the HVAC Control Line and put a Vacuum pump on the tubing and draw 15 in. Hg. and let it sit for 15 minutes or so and re-check the gauge.

Attach the pump to the Solenoid, and draw 15 in. Hg. and let it sit for 15 minutes or so and re-check the gauge.

Attach the Vacuum pump to the Reservoir and draw 15 in. Hg. and let it sit for 15 minutes or so and re-check the gauge.

One of these will loose Vacuum, that will isolate the circuit or device.

Once that has been determined, you will have to separate each circuit i.e.: Left / Right Wheel Lines, fittings, O-Rings, Seals, Tubing, etc.