Troubleshooting drivetrain issues

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deadlysilent

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Gentlemen, it’s a sad day in the raptor world. First off, I have a Gen1 2010 scab 68k miles. Took the truck up to the snow recently. While sitting in bumper to bumper traffic, there was very little snow on the ground and roads were wet/slushy. I decided to just nudge the throttle a little extra for some shock and aww.

The truck did what it was asked and spun the tires for approximately 3 seconds. The rear end fishtailed slightly and I applied the brake to settle her down and proceed into the basically stopped line of vehicles.

When I applied the brake, there was a dreadful pop sound (I was in 2wd) that sounded like it came from the drivers side under the vehicle. I slow rolled back into my spot in line and continued to roll at speeds of 1/2 mph. As traffic began to start rolling again, from a dead stop I slowly applied throttle and the rear end began to walk out from under me. The way I described it was as if I was only getting power to the passenger side rear axle shaft.

I was unable to get traction and the rear end washed out every time. Due to the traffic slowly moving I placed the vehicle into 4wd high to obtain some front wheel traction I heard a loud pop sound again which made me think transfer case. The truck did not display any warnings and the truck acted normal for a short while.

Not wanting to become stranded on the mountain, I retuned back down the hill. The truck drove without issues until I reached civilization, where I removed the truck from 4H to 2wd again. Heard a pop sound again which again sounded like it was the front driver side region. (It Should be noted, the front cv sounded and felt like vibration prior to the shenanigans).

During my travels home, the decent control light came on (it disappeared after the truck shut off and turned back on).

My thoughts, there wasn’t enough traction in the road to really put excessive strain on the drivetrain to cause breakage. Plus, the pop sound may have been coming from transfer case or IWE. My what would cause the rear end from sliding out and losing traction from a crawl speed?

I haven’t diagnosed or tore into the truck yet, but did observe a torn cv bolt on the passenger side front. Possibly busted the posi rear?

Thoughts...
 

Dane

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Couple things. This sounds like a classic IWE issue - which can also break your CV, but you'd typically see it all twisted up. So I think you broke your IWE - possibly due to vacuum issues, so don't JUST fix the IWE.

I don't think it's your transfer case.

The truck doesn't have a rear posi, so it's definitely not that. So far I'm not concerned about that rear. If you blew the rear diff, neither tire would be spinning. These trucks have an open rear unless you lock it.

Examine your front axle shafts, troubleshoot your IWE and vacuum system. I think you have a bad IWE.
 
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deadlysilent

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Couple things. This sounds like a classic IWE issue - which can also break your CV, but you'd typically see it all twisted up. So I think you broke your IWE - possibly due to vacuum issues, so don't JUST fix the IWE.

I don't think it's your transfer case.

The truck doesn't have a rear posi, so it's definitely not that. So far I'm not concerned about that rear. If you blew the rear diff, neither tire would be spinning. These trucks have an open rear unless you lock it.

Examine your front axle shafts, troubleshoot your IWE and vacuum system. I think you have a bad IWE.

That’s the way I was leaning, but the rear end was acting funny immediately following the pop sound. I’ve examined the hoses connected to the hubs looking for an obvious disconnected hose or what have you. But did not see anything out of place.

You’re probably right, there may be a leak throughout the vacuum hoses. I will attempt a vacuum test and see if I’m losing pressure. I’ve seen IWE upgraded lines made by Forged Off-road. May have to upgrade just because. I mean my truck is turning 10 y/o this February, So time for some upgrades.

Also the hill decent controller has been traced back to the 3rd brake light saturation. But it is a new/replaced housing due to previous issues 1.5 years ago. No issues since the swap and have received copious amounts of rainfall since (Washington State).
 

Dane

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That’s the way I was leaning, but the rear end was acting funny immediately following the pop sound. I’ve examined the hoses connected to the hubs looking for an obvious disconnected hose or what have you. But did not see anything out of place.

You’re probably right, there may be a leak throughout the vacuum hoses. I will attempt a vacuum test and see if I’m losing pressure. I’ve seen IWE upgraded lines made by Forged Off-road. May have to upgrade just because. I mean my truck is turning 10 y/o this February, So time for some upgrades.

Also the hill decent controller has been traced back to the 3rd brake light saturation. But it is a new/replaced housing due to previous issues 1.5 years ago. No issues since the swap and have received copious amounts of rainfall since (Washington State).
Yup, low vacuum can cause IWE issues - including major failure, which I suspect you have. Vacuum test the lines. I've replaced mine with OEM once - easy 15 minute job. I think they cost $30. Yes, you can get the upgraded silicone ones if you like.
I think you were just losing traction in the rear, which likely means just one wheel spinning and maybe walking to the side. I bet if you had locked the diff, both wheels would have spun.

Gotta replace that IWE if it failed though. Give those CVs a good look too. I've broken both IWEs and CV. They both have a dreadful pop. I have also had the dreadful pop and not broken anything - though never in 2wd.
 

GCATX

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Just spit balling here, you might check your front brake calipers. Perhaps 1 is seizing or a pin backed out. Anyway, best of luck with it.
 
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deadlysilent

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From what I’ve read during my research of the IWE system, it states the IWE remains unlocked during vacuum. It says in the event of low pressure or vacuum loss/leak a partial IWE may be engaged and cause damage due to improper seating of the toothed rings.

Would it be worth it to just replace all IWE parts as a peace of mind? Can you leak test the solenoid?
 

Dane

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From what I’ve read during my research of the IWE system, it states the IWE remains unlocked during vacuum. It says in the event of low pressure or vacuum loss/leak a partial IWE may be engaged and cause damage due to improper seating of the toothed rings.

Would it be worth it to just replace all IWE parts as a peace of mind? Can you leak test the solenoid?

Correct. With no vacuum (truck off, failure of vacuum, switched into 4WD) the IWE engages the front axle to the wheel bearing. When you hold the IWE in your hand you can squish it - simulating vacuum and disconnecting the axle from the wheel bearing. When you let go, it springs back out which would provide the connection. Under normal driving (2WD) the vacuum line holds the IWE squished. If you have a vacuum leak, the amount of vacuum can be insufficient, which lets the IWE attempt to partially engage - CONSTANTLY. This chews up the ring that connects everything and quickly leads to failure. Then when you actually try to go into 4wd, the ring can't bind - slips out under load, and you get a WHAM! Sometimes this does other nasty stuff like break a CV or the IWE entirely. Typically, one way or another you lose 4wd. Sometimes everything holds and the ring re-engages. It's really a crap shoot. Your description sounds like the IWE partially engaging and then not holding - even though this shouldn't happen in 2wd, with a vacuum leak, it can.

Long story short, I'd definitely replace your IWE. It's all one piece. Also, check the axle nut. If that comes loose it has the same effect as the IWE failure, it just happens from the other direction since the axle now has play allowing it to disengage from the IWE. The IWEs aren't too expensive. A dealer will gouge you on labor, but it's not a terrible job to do yourself. If you're going to do it, consider the upgraded RCV rings since you'll be right there anyway.

I now carry a spare IWE, and could change it on the trail if need be - though I wouldn't be happy about it.
 
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deadlysilent

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Correct. With no vacuum (truck off, failure of vacuum, switched into 4WD) the IWE engages the front axle to the wheel bearing. When you hold the IWE in your hand you can squish it - simulating vacuum and disconnecting the axle from the wheel bearing. When you let go, it springs back out which would provide the connection. Under normal driving (2WD) the vacuum line holds the IWE squished. If you have a vacuum leak, the amount of vacuum can be insufficient, which lets the IWE attempt to partially engage - CONSTANTLY. This chews up the ring that connects everything and quickly leads to failure. Then when you actually try to go into 4wd, the ring can't bind - slips out under load, and you get a WHAM! Sometimes this does other nasty stuff like break a CV or the IWE entirely. Typically, one way or another you lose 4wd. Sometimes everything holds and the ring re-engages. It's really a crap shoot. Your description sounds like the IWE partially engaging and then not holding - even though this shouldn't happen in 2wd, with a vacuum leak, it can.

Long story short, I'd definitely replace your IWE. It's all one piece. Also, check the axle nut. If that comes loose it has the same effect as the IWE failure, it just happens from the other direction since the axle now has play allowing it to disengage from the IWE. The IWEs aren't too expensive. A dealer will gouge you on labor, but it's not a terrible job to do yourself. If you're going to do it, consider the upgraded RCV rings since you'll be right there anyway.

I now carry a spare IWE, and could change it on the trail if need be - though I wouldn't be happy about it.

I’m comfortable doing the swap, but you mentioned the upgraded RCV rings. The last time I checked, I thought those were IWE eliminators, which basically keeps the truck always locked into 4wd? I don’t want to always be engaged.

I think I’ll do some more research to find out answers to my own questions.
 

MTF

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I believe they make the gear slightly thicker for full engagement.
I'm not sure who makes them but someone will chime in.
 

Dane

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I believe they make the gear slightly thicker for full engagement.
I'm not sure who makes them but someone will chime in.
RCV does. I have them. Not talking about eliminators, but just as described above. I haven’t broken anything since switching to them. I bought them from RPG. They’re spendy bastards, but what’s worth not blowing out your 4x4 on a trip worth??

They are these:
https://www.rpgoffroad.com/product/rcv-iwe-rings/
The “thicker” ones, not eliminators. Not sure why that page says 17 and up, it’s listed under the Gen1 stuff. Whatever. Call them. I guarantee you they exist for Gen1. I have them on my truck.
 
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