Hoping to get some ideas from the collective. I had the exhaust manifold studs replaced by a local shop 11/13, along w/ an oil change and tire rotate. On 11/17, it had snowed overnight, and my 4x4 didn't engage auto. Here's a timeline:

11/9; 154,480: Cat back exhaust system installed

11/13; 154,500: Oil change, rotate tires, replace broken studs in exhaust manifold by local Midas shop (trusted by a friend)

11/14 – 17; 154,5xx – 155,000: Hunting weekend. Did not notice anything driving to property. Monday morning driving to property, turned on 4x4, did not engage. Climate control defaulted to defrost mode. Manually lock hubs, 4x4 works, but slight crunch noise when disengaged while driving home. Approx 200 miles each direction, less than 30 miles while hunting.

11/18 & 19: Wake up to snow, manually engage hubs to get to work. Disengage when I get to the office. 4 mile one-way commute. Crunching when leaving work, but stops.

11/20: No 4x4 in morning, some noises, but not bad.

11/21-23: Parked for long weekend
11/23: Weather was warm, so tried to track down the vacuum leak unsuccessfully, but noticed that the vacuum accumulator was not fully bolted down. 1 nut missing, others nearly off. Tightened two remaining nuts. No obvious hose leaks.

11/24: Leaving for work, MAJOR crunching and shudder front end, multiple times while still in neighborhood. Seems to happen after turning, but not consistent. Leaving work for Kroger, no crunching. Backing into Kroger parking spot, light “tick, tick, tick.” Consistent rhythm with speed, can feel and hear. 1 mile home, no noise. Backing into driveway, slight ticking.

11/25: Driving to work, no noise. Slight ticking noise when slowly (idle speed) coming to traffic light to turn left.

Still locked in defrost mode. Toes are getting cold!

So, what does the collective think? Is it possible that what needed to be removed for the exhaust manifold repair could have screwed up my vacuum system, leading to the 4x4 not correctly working (and leading to a major crunch, which I assume is a hub and hopefully not the transfer case!) Or coincidence? What could the crunch be?

Thanks!
Kevin

 

I think you're on the right track. I would take it back to the shop and tell him what you've typed above. Vacuum lines would be my number 1 suspect.

 

Any kind of binding in the front end driveline will cause some funny sounds. You should be feeling them big time in the steering wheel too. Even with the 4x4 disengaged, but the hubs locked, you will feel and hear some funny things driving around especially when in tight turns. Checking the vacuum lines are the first place to start. Well, actually, make sure the vacuum pump is working.

Just realized you have a V-10. No, they don't have a vacuum pump.

 

V10 has a vacuum pump?

 

Sorry. No it does not. I was thinking diesel.

 

Take a look at the vacuum seals Inboard of the knuckles.
Does the axle move when you wiggle the axle shaft. It shouldn't move much if at all. If it does a vacuum seal would be a likely suspect. Pull a vacuum on it to prove it holds vacuum. Clickity crunch I'm thinking the needle bearing supporting the stub axle through the hub bearing. Dry needle bearing leads to stub axle carnage. When the hub locks are engaged the needle bearing and axle turn at the same speed. Unlock the hub lock the axle sits at rest and the needle bearing spins along with the hub bearing it is married to. Click crunch grind.

 

also check the rubber vacuum lines from the frame down to the nipple in the steering knuckles. they rot and crumble ALL the time about three dollars to fix

 

I'll have to check this out. Looking at this website, it appears that this could be the issue. It also appears that it could be an expensive repair after already spending $874 on a exhaust stud repair.

If it is this, could it have been caused by the mechanics who did the repair? Ie, if they damaged a line or didn't connect things properly, could it have caused "stub axle carnage"? Do I have any ground to stand on to have the Midas absorb some or all of the cost for this repair?

I'll head out tonight and crawl under the truck (should be fun at 30 degrees!)

Kevin

 

The heater goes to defrost as a default when you lose vacuum. You have a vacuum leak somewhere.
Driving with the hubs locked in should not be producing any noises. There are MANY vehicles on the road that don't use hubs; the front axles are locked in all the time. Late model Ford Rangers are a good example- the only thing that engages/disengages is the transfercase. If running with the hubs locked (but the transfercase in 2WD) causes noises, you have a mechanical issue.

 

Hubs UNLOCKED, but w/ noise. Daughter (who has way better hearing than me!) said it sounded like a tin can full of gravel. I guess I need to get my hearing checked again!

My brother came home from OKC last night, so I didn't make it under the truck. Today after work.

K

 

Most likely, you have a hub that has debris in it, and the noises are the debris grinding against the stationary axle shaft end. Hopefully, just a hub rebuild or replacement will fix things, and the axle stub isn't hurt. I would pull it apart and check it before driving more. If you are getting noise, you are getting damage.

 

Finally was able to crawl under the truck w/ a pry bar. Press on the U-joint on the drivers side and everything was tight. Passenger side has a little less than a quarter inch of movement.

Is this what I'm hearing, or should I start pulling the hubs? Weather seems decent for the next few days, I won't be TOO cold working outside and I've got the time off!

So, what should I start taking apart? Any suggested "how-to" websites before I start tearing into it? I'm a capable mechanic when I have directions. Tackled ball joints once on this truck. That sucked!

Thanks!
K

 

Pulling the locking hubs is easy, I'd start there. A pair of needle nose pliers to pull the snap ring off, and the hub comes out. See if those are OK.

 

Hubs look good. I didn't break them down, just pulled them out, inspected the inner and outer teeth, and put them back in.

Passenger side had grease on the external portion of the hub and on the snap ring. Driver side was dry/clean.

Next? Thanks!!
Kevin

 

Could you tell where the movement was coming from? U-joint? The shaft from the hub? or the one coming from the differential?