What did I break??

[lhsnbsaoa]

Last week, a Duramax challenged me at a stoplight. I should have let him go, but I did the stupid thing, put my truck in 4hi and went for it, leaving the intersection, and the Dmax in a cloud of black smoke. Problem is, now my 4wd doesn't work unless I manually lock the hubs (which I've never had to do before). Also it looks like some kind of seal popped out. I am including a picture, can anyone identify the problem?? Any input is helpful..

[Tmoney511]

When you took off in 4 high did you hear anything pop at all?

[Diesel Addict]

Not sure about your 4wd it is vacuum operated so you might want to check the pump for them which I think is on the pass. side inner fender. Or you could have one hub working and one not, with the auto hub, which would act like its not in 4wd but when you manually lock them it would work. Also that seal is just a dust seal. Its a common thing for them to pop out like that, its not really needed it just helps to protect the inner axle seals. Mine have been out like that for over 30k miles with no problems. Sorry I couldn't shine more light on your 4wd, somebody will I'm sure.

[lhsnbsaoa]

Originally Posted by Tmoney511

When you took off in 4 high did you hear anything pop at all?

There might have been a pop, but I cannot say for certain.

[lhsnbsaoa]

Originally Posted by Diesel Addict

Not sure about your 4wd it is vacuum operated so you might want to check the pump for them which I think is on the pass. side inner fender. Or you could have one hub working and one not, with the auto hub, which would act like its not in 4wd but when you manually lock them it would work. Also that seal is just a dust seal. Its a common thing for them to pop out like that, its not really needed it just helps to protect the inner axle seals. Mine have been out like that for over 30k miles with no problems. Sorry I couldn't shine more light on your 4wd, somebody will I'm sure.

Is there any way to test the hubs? I had these installed by the dealer about a year ago.

[Tmoney511]

Originally Posted by lhsnbsaoa

There might have been a pop, but I cannot say for certain.

I was in a 7.3 that blew both its hubs upfront. They exploded and that was LOUD. You could lock it in 4 high and have someone stand outside to watch what happens. But I would check vacuum like the other guy said.

[lhsnbsaoa]

So im positive that the 4wd is working with the hubs locked, just not when they are unlocked. Does that mean that my hubs are ok? How would I go about testing the vaccuum system? Everything is still hooked up.

[Diesel Addict]

To get your 4wd to work you have to manually lock the hubs in, right? Do you know if your front driveshaft is spinning when you put it in 4wd? If the shaft is spinning, but 4wd is not working when you shift into it without manually locking the hubs then yes I would assume its a vacuum problem. I don't know how to diagnose it those just have had a similar problem on an excursion, but I just got out and locked the hubs after that. You do have the shift on the fly 4wd with the knob on the dash, correct?

[lhsnbsaoa]

Originally Posted by Diesel Addict

To get your 4wd to work you have to manually lock the hubs in, right? Do you know if your front driveshaft is spinning when you put it in 4wd? If the shaft is spinning, but 4wd is not working when you shift into it without manually locking the hubs then yes I would assume its a vacuum problem. I don't know how to diagnose it those just have had a similar problem on an excursion, but I just got out and locked the hubs after that. You do have the shift on the fly 4wd with the knob on the dash, correct?

Correct, I have to manually lock the hubs in (the turn without a problem), but it does not work in the "auto" position.

I do have the shift on the fly. I will check out and see if the drive shaft is spinning or not.