Gen 2 Raptor Vacuum System

[New recaros]

So, supposedly Ford engineered a way to slightly warm the diff. They have the hubs disengage at some arbitrary mileage. Ok, well what happens when you’re driving in sub 32F weather? It cools back off, suddenly the strategy falls apart unless Ford re-engages to keep the system warm. No offense to anyone, especially FT1, but I don’t buy the strategy put up today.
I don’t know this system, but I do know a lot about others. This strategy would be a total waste as the parts that warm up would cool off and you would end up right where you started in just a few miles after disengaging.

 

[brfails]

I don’t see where you have checked the hub itself.

Would the hub effect vacuum, or would it just effect the ability of the actuator to engage properly?

 

[New recaros]

Would the hub effect vacuum, or would it just effect the ability of the actuator to engage properly?

You pull a vacuum to disengage. If it leaks a small amount you can’t pull sufficient vacuum. That can be checked by pulling a vacuum and see if bleeds off quickly.

 

[New recaros]

Would the hub effect vacuum, or would it just effect the ability of the actuator to engage properly?

You pull a vacuum to disengage. If it leaks a small amount you can’t pull sufficient vacuum. That can be checked by pulling a vacuum and see if bleeds off quickly. I

 

[fordfreek]

So, supposedly Ford engineered a way to slightly warm the diff. They have the hubs disengage at some arbitrary mileage. Ok, well what happens when you’re driving in sub 32F weather? It cools back off, suddenly the strategy falls apart unless Ford re-engages to keep the system warm. No offense to anyone, especially FT1, but I don’t buy the strategy put up today.
I don’t know this system, but I do know a lot about others. This strategy would be a total waste as the parts that warm up would cool off and you would end up right where you started in just a few miles after disengaging.

You tee in a vacuum gage and run it inside the vehicle. Start the truck and take it for a test drive. It does it once per ignition cycle, as soon you start the truck. They came up with this strategy because the early version of this system never engaged the hubs unless you engaged 4wd, which allowed the ring and pinion to sit in the same position for months, even years. This, along with the warm engine in a cold climate and cold front differential allows excess condensation to build up in the front differential, rusting or pitting the bearings. I think alot of cold climate areas saw alot of warranty claims for this, that's why they came up with this strategy.

 

[New recaros]

I understand a need to turn things. I had a limited a few years ago that developed at vibration at 42 mph. They said transfer case as the driveline spun to fast, no help, then the hubs, no help. Finally it was the front differential. They stated the transfer case spins the front end with hubs disengaged at 60% speed. This allowed for smooth shifting into 4 wheel drive.
Back to the problem at hand, low vacuum in the system.

 

[FordTechOne]

So, supposedly Ford engineered a way to slightly warm the diff. They have the hubs disengage at some arbitrary mileage. Ok, well what happens when you’re driving in sub 32F weather? It cools back off, suddenly the strategy falls apart unless Ford re-engages to keep the system warm. No offense to anyone, especially FT1, but I don’t buy the strategy put up today.
I don’t know this system, but I do know a lot about others. This strategy would be a total waste as the parts that warm up would cool off and you would end up right where you started in just a few miles after disengaging.

You’re over thinking it. The startup sequence slightly warms up the fluid and distributes it throughout the differential. That’s all it needs to be ready for subsequent re-engagement. The primary purpose of the strategy is to prevent partial engagement during vacuum intensive engine warm up/catalyst light off.

The published diagnostics take the strategy into account, it’s not hard to properly diagnose.

 

[Ellison3]

I just removed the vacuum system out of the equation by swapping out the vacuum actuated IWE’s for the ones that stay engaged. I have no more intermittent grinding.

I wanted the system to work as designed, but don’t want to re-diagnose when another part of the system fails.

 

[EricM]

IWEs are only good for MPGs. Otherwise it's just a failure waiting to happen at the worst time.

Pre 2004 trucks never had such a complex system for hubs.

 

[Ellison3]

IWEs are only good for MPGs. Otherwise it's just a failure waiting to happen at the worst time.

Pre 2004 trucks never had such a complex system for hubs.

I agree… so I dumped them for the “non-vacuum” replacements.