Diagnosing bad front differential and transfer case???? 2000 mountaineer 5.0 awd 225,000 miles

[Summajet]

I searched on proper way to diagnose a bad front differential and/or transfer case before posting.

When speaking to two separate 4wd shops they said never drive without the front shaft in as it will damage and cause the viscious coupling to fail??? Said driving more than a mile will cause failure? Has anyone else heard this also?

I have attached some pictures as you can see in the pictures there is grease slung on the underside of the floorboards. I am thinking it is the front diff binding and adding pressure onto the viscious coupling causing it to leak and will fail also soon. The Viscious coupling should not sling any grease, or is it grease from the old front intermediate shaft that was leaking?????

I did notice with both cv axles removed from the front diff I could see the bearings. I did not see the racer covering the bearings, I should have seen the racers covering the bearings as the cv axle shafts rest on the racers and then turns on the bearings? I am thinking the bearings/racers could be the issue??

I want to diagnose it further before replacing any other parts.
Parts replaced so far,
CV Axles, Axle Hubs, lower ball joints, front intermediate axle shaft, replaced front brake caliper

After everything was reassembled it seems like when it is put in forward with all 4 tires off the ground it is binding up on the drivers side of the front differential. The passengers side front tire spins without binding up.

Upon road test I can hear the noise/hum from the pinion gear on the front differential. It has a vibration still and can feel in the steering wheel at 55mph. Axle hubs were bad and the vibration is better than before

About 5 years ago the OEM intermediate shaft had failed and was banging/falling apart so it was replaced with a remanufactured shaft at my local repair shop.
I did contact a local 4wd repair shop. they are backed up for 2 months. Said a re-manufactured front diff out of Michigan was $1,200 and $600 in labor if that was the issue.
Called a local auto parts yard and I can get the following,
front differential for $400 (2yrs warranty unlimited mileage) out of a explorer with 120,000 miles
transfer case $500 same warranty above and explorer with 90,000 miles.

Diagnose front Differential
1. I was thinking remove the front tires and remove the front intermediate shaft.
2. Then turn the pinion by hand and feel for any resistance and/or grinding noise.

Also how much play should there be when rocking the pinion gear left to right? Also look for any play when pushing the pinion forwards and pulling back on it?

Diagnose the transfer case
1. leave intermediate shaft out on the front transfer case and wheels off.
2. Jack up rear and have tires off the ground.
3. Start it up and put in gear and look to see if the viscious coupling is turning or binding up??

I appreciate any input or suggestions
Thanks!!!

 

[Turdle]

If the truck was fully lifted with front wheels dropped past their limits the front cv axle will bind. It is past it working angle. Grease was most likely from previous failed cv joint.

 

[Summajet]

If the truck was fully lifted with front wheels dropped past their limits the front cv axle will bind. It is past it working angle. Grease was most likely from previous failed cv joint.

I had the front tires removed and the front two shafts had no support. I will test it again with the two front shafts supported on the bottom of the spindles.

One other thing that I hear now and after the cv axles and hubs installed is that front driver side now has a squeaking sound. sounds like rubber and it is as the axle turns. More noticeably when driving abour 5-10 mph forward. Some rubber noise when in reverse.

 

[C420sailor]

I had a rubber squeal at slow speed after replacing CV axles and differential seals. It eventually went away.

As mentioned, front axles have to be relatively straight to keep from binding.

 

[Turdle]

I also have that annoying new cv squeal going on, not really sure what to do about that other than some silicone spray.

 

[C420sailor]

Also, culprit number 1 on these trucks is the front shaft CV. They fail and sling grease everywhere. And they don’t last long.

Mine made an annoying part-throttle rattle that I swore up and down was the serp belt tensioner.

 

[Summajet]

Also, culprit number 1 on these trucks is the front shaft CV. They fail and sling grease everywhere. And they don’t last long.

Mine made an annoying part-throttle rattle that I swore up and down was the serp belt tensioner.

I was thinking the grease was from the previous front shaft. Have you ever replaced the carrier bearings in the front diff tubes? The 4wd shop said typically the carrier bearings fail. Generally when they fail they crack or worse break the ends of the diff tubes apart.

 

[C420sailor]

I was thinking the grease was from the previous front shaft. Have you ever replaced the carrier bearings in the front diff tubes? The 4wd shop said typically the carrier bearings fail. Generally when they fail they crack or worse break the ends of the diff tubes apart.

Nah, I haven’t. These differentials are surprisingly durable if you keep fluid in them and don’t beat on them. One of my trucks has 314k on both the front and rear diffs, and they look great internally.

I only tried to drive my AWD once without a front shaft, and the TC made a terrible sound. I put the shaft back in and it vanished. Some guys report no issues driving without one.

You can try, maybe take a quick lap around the block to see if the sound went away?

I’ve also seen dudes put gopros under their truck, drive, then move it to another suspect location and repeat...whichever video is louder identifies the culprit.

 

[Summajet]

Nah, I haven’t. These differentials are surprisingly durable if you keep fluid in them and don’t beat on them. One of my trucks has 314k on both the front and rear diffs, and they look great internally.

I only tried to drive my AWD once without a front shaft, and the TC made a terrible sound. I put the shaft back in and it vanished. Some guys report no issues driving without one.

You can try, maybe take a quick lap around the block to see if the sound went away?

I’ve also seen dudes put gopros under their truck, drive, then move it to another suspect location and repeat...whichever video is louder identifies the culprit.

I will look at it this weekend. I can hear the pinion like a whirl sound at certain speeds. Thinking I will drop diff out and pop off front cover and look inside housing and go from there. If bad I'll get a replacement from a yard.