johnday in BFE

iTrader: (1)

Due to the amount of problems with the IWE system on these trucks, and the amount of threads stated recently, I thought I'd try to make it easier for members to read about, and possibly fix their problem. Ya, I know, it's been tried before.
This will not be a cureall for all problems, but a place to start troubleshooting.
The system is pretty simple, vacuum supplied from the engine is used to keep the hubs DISENGAGED. As you accelerate, vacuum drops off the engine, and when in boost, on an Egoboost, you actually pressurize the area just behind the throttle body, where the vacuum is normally supplied to the system. On the hose going to your solenoid, there is a checkvalve, a round black/white thingy. When under pressure, the checkvalve is supposed to close, and prevent loss of vacuum to the hubs. Downstream of that checkvalve is the 4X4 solenoid. When in 2wd, this solenoid provides vacuum to the hubs keeping them disengaged. Upon loss of vacuum, usually when you turn the 4X4 switch, this solenoid throws over to vent the hubs, allowing the actuators to ENGAGE.
What some are seeing, when accelerating, usually lightly, is that checkvalve doesn't always close, and instead of vacuum, the system is being pressurized, and the hubs either engaging, or partially engaging, or just trying to engage, causing the rock in the rotor, the shaking paint can sound. Sometimes so badly it can be felt through the steering wheel.
One thing to do when this happens, is to jump off the throttle, or maintain your pressure on the pedal, and throw it in 4X4. If the sound/vibration stops, chances are pretty good the checkvalve didn't close to maintain vacuum.
The valve you want is a YG360, available at the dealer, and rumor has it, at various parts stores. That's for a 13th gen, the 12th gen is different, here is the part # for that AFAIK,
For the 13th gen, on the Amazon website it's available as well, it says does not fit 2017, maybe some others. Ignore it, it's the exact thing I bought over the counter at my dealer.

What I did, was replace the stock one, and also put another one in line, series/tandem, whatever, to ensure if one goes bad, the other will back it up..
I'm not addressing the solenoid in this write up, and it's possible the solenoid may be your problem, but what myself, and others are seeing, the checkvalve is a likely candidate, and the cheapest part to replace $10USD, or less on line, or parts store.
This covers all 13th gen, and it appears all 12th gen. Older are likely the same, but no guarantee from me.
The 12th gen check is a little different than the 13th, and usually mounted on the firewall on the left side. 13 th gen this is mounted on the left side as well.
Here's a photo of my 13th gen, with both checkvalves in series. The solenoid is the device at the end of the vacuum line. That other connection on the solenoid, goes down to a tee fitting, that splits off to both the left and right actuaters.
Again, this is NOT a cureall, your mileage may differ.

techrep

iTrader: (1)

Nice write up John...

johnday in BFE

iTrader: (1)

Thanks Mark, I tried to keep it simple.

Blue2016XL

Question. I have a 2010. It is my understanding that it is a 12th gen. truck. Mine and at least one other that has a 2010 are also mounted on the drivers side, same as the 13th gen. It is my understanding that it was mounted on the passenger side on 2008 and older.

johnday in BFE

iTrader: (1)

I do believe you're right. Yes, 2009-2014 are all 12th gen.

Oh, and thanks for sending me that solenoid, I still owe ya.

Blue2016XL

You are welcome. Looking forward to seeing your results.

raisin

Turned out that my check valve and hose asm. for my 2014 5.0 V8 (Gen 12) is BL3Z-3A788-A and is $25.26. The picture tascaparts.com sent me is my part.
So now I have order for gen 12 and gen 13 hose/checkvalve plus solenoid. Which is being held by storm out east.
johnday I'm wondering how mine being 5.0 without boost is affected by bad checkvalve. Seems it should always have good vacuum. When it did it in Colorado Rockies pulling grade it stopped when I let off gas...


Then it did it the other day at 5mph at 5 degrees.

Blue2016XL

Vacuum will drop on any engine under certain circumstances. Hence the need for the check valve. If a vacuum was never an issue, a check valve wouldn't be needed. Yes, vacuum is more likely to drop under conditions where the engine has to work harder and when you let off the gas the load is removed and vacuum level returns.

Tinker2

Great information and very thorough explanation. Thank you ! My 16 hasn't exhibited any of these symptoms and hopefully doesn't. However should it start I'll know what the culprit is !


Edit question, what does IWE stand for ?

johnday in BFE

iTrader: (1)

Anytime you accelerate, the vacuum drops on your engine. Somewhere/someone came out with the statement that at 8" of vacuum the hubs will start to engage. That isn't much vacuum.
When you're turbocharged, and the turbo spools up, gains rpm due to increased exhaust flow, the intake manifold becomes pressurized.
Same thing with a supercharger, only faster than a turbo reacts.