Anyone ever had this issue with AWD and Front Differential?

[Shane91Explorer]

I know this is long, but I feel I should tell the entire story to see if there are any similar stories out there. Any help or suggestions would rock!

My brother bought a 2000 EB Ex back in October of 2008. He bought it with he knowledge something was wrong in the front end (at the time we thought it was a wheel bearing). We also knew it was leaking some oil from somewhere, but it was unknown as to where it was coming from. We looked and found someone had already replaced the intake manifold gaskets and there was a puddle of oil up by the cam position sensor, so I replaced all of the intake gaskets, etc.

We were still getting oil and the front end noise was getting worse. After quite a time looking into this, I determined the front differential was the source of the noise and the unexplained oil all over EVERYTHING. The driver side seal had blown out on the differential. So we replaced the differential with junk yard unit and all is well......for about 2 weeks. My brother was driving it down the freeway and gets a could of smoke followed by an awful smell (burnt 80W 90 smells like natural gas). Same story, blown driver side seal.

So we thought it must have been a bad unit, so we put in another differential (and another in between - the buttholes at the junk yard gave us a 4.10 instead of a 3.73) as well as a and it was fine all through the winter when the temps were low. We also did the seals and put a new driver side CV joint in. Back in March when the weather was starting to warm up, my brother called me and told me there was a loud banging sound coming from the front end and he had taken it to a Midas to look at it. Midas said he needed new differential and CV joint - and some astronomical amount to fix it. I told him it sounded fishy, so he had it towed to my house. I determined it was a bad CV joint on the front driveshaft. So had had it rebuilt, and presto the noise was gone.

Fast forward to May. He was going down the freeway last weekend and the same smoke and smell comes from underneath. This time it was the breather tube it blew out of. He immediately stopped and had it towed to my house again. It seems to be overheating - it only does it when it's warm and under high speed.

Yesterday we did the swap AGAIN. I decided there's got to be another cause. I looked into the newly rebuilt driveshaft and noticed a tone of wheel bearing grease thrown all over right by the CV style coupling that connects to the transfer case. Come to find out, half of the boot is missing, and this CV joint is bad again.

My buddy owns a transmission shop and he told me to look at the transfer case fluid and see if the fluid is burnt. I pulled the fill (top) plug to check the level of the fluid and found that it is over filled. So I called my friend and he said the trans is probably leaking into the transfer case and filled it all the way up.

And this is where I'm stuck and the questions begin.

1. Would the AWD Transfer case being too full mess with the function of the viscous coupling and cause it to trash 2 drivelines and 3 differentials?

2. Is there any other way to get that much fluid into the transfer case? I would say it is chuck full. BTW, the trans is full too - someone else may have topped it off though.

3. Are there any other things I should check?

4. How hard is a T-Case to rebuild?

5. Is the gasket between the T-Case and trans easy to replace?

Thanks SO MUCH!

 

[Shane91Explorer]

We changed the fluid in the transfer case this morning. It had about 3 quarts in it. I suspect the seal is allowing ATF out of the trans into the t-case. We filled it to the fill hole and are going to watch it now. We also put the newly rebuilt front driveline in (2nd time being built).

To try and alleviate any possible re-occurrence with the differential woes, I added some length to the breather tube. We also put Lucas 80W-90 in it with friction modifier. The tech I talked to at the Ford dealer said the friction modifier may not help, but it would not hurt, so we did it.

Anyway, overall it's a great little truck when the front differential is working. This is the 4th front diff install, so I feel pretty experienced doing this swap now. BTW, we've done the swap on the ground 3 times and on a lift once (my friend has a transmission shop). IMHO, the ground is much easier because it compresses the drivers side suspension and makes it easier to get the drivers side CV in, and allows easier access to the pain in the a$$ top mount bolt on the diff housing. Does anyone know if the 8.8 front diff out of an Expedition would work for a swap in an Explorer? It seems much more dependable. Plus I would rather have a Ford diff than a Dana any day.

Thanks!

 

[hworksinc]

Was there any sign of binding in the front diff before they blew out? Could be that the viscous coupling in the xfer case is trashed, and that the truck is effectively locked in 4WD, thus putting stress on the weaker differential (the front one).

Try removing the front driveshaft and park the truck on a hill - the truck should slowly move a bit if the viscous coupling is good. If the truck doesn't move at all while parked on a hill with the front driveshaft off, then it means the viscous coupling is likely shot, and a transfer case rebuild is in order.

Also, have you taken apart the old front differentials after they had problems? Was there evidence of mechanical problems (eg metal shavings etc.) or was it just burnt gear oil?

Don't know about the 8.8 swap - i have a feeling it wouldn't work without significant modifications. Before you do ANYTHING else though, you need to check the transfer case to see if the viscous coupling is good.

 

[Shane91Explorer]

Was there any sign of binding in the front diff before they blew out?

- There wasn't until this last time. In fact something still seems like it's bound. It takes a little extra on the gas pedal to make it move.

Try removing the front driveshaft and park the truck on a hill - the truck should slowly move a bit if the viscous coupling is good. If the truck doesn't move at all while parked on a hill with the front driveshaft off, then it means the viscous coupling is likely shot, and a transfer case rebuild is in order.

- I'm going to try this one morning this week. It's not a DD in the summer, so we have time to take it slow. As long as it's ready for winter, we're good. If it's bad, this will be my first t-case build. I would imagine this will be easier than the one in my explorer (1354 - manual).

Also, have you taken apart the old front differentials after they had problems?

- I took apart the first one, which had been bad for who knows how long. It was bad when he bought it. Anyway, it was trashed - the gears were very worn, and it had no oil at all.

Was there evidence of mechanical problems (eg metal shavings etc.) or was it just burnt gear oil?

- The second one was replaced under warranty through the wrecking yard, so I did not open it. This latest one I opened. It had a small amount of metal shavings. But the gears look great, although it smells terrible. My neighbors keep asking if I have a natural gas leak because burnt gear oil smells just like natural gas.

 

[reserved50]

im no rocket scientist but theres something seriously wrong here . When you opened the front and rear diff covers they both had the same gear ratios stamped on the gears?

 

[Shane91Explorer]

Removed the front driveshaft this morning (despite the rain)

It's been raining all week, so I just got tired of waiting for it to stop and pulled the front shaft. It's parked on an incline right now and it's not moving. I even tried to push it, and it just bounces back like it normally would. I'm assuming this means the viscous coupling is indeed shot?

This would sure explain a lot!

 

[howellma]

I have the same problem with my 2004 mountaineer. But it happened while towing our camper with a new wd hitch. Oil sprayed out the breather tube, very burnt smell. Got vehicle home, rebuilt front diff with all new bearings, went to get camper and it started to smell before we got there and it happened again pulling camper home. Now we are contemplating the front diff again and replacing the viscous clutch. Thought about a used transfer case but dont know what shape that would be in.

Very interested in your results.

 

[99SportX]

It wont roll fast, if you leave it on a hill for an hour it should move a few feet at least depending on the slope.

I had mine roll about 10 feet and block a lane in a parking lot once. It was only there for about an hour, haha

If the coupling is indeed frozen up it should not roll.

I definitely suspect a t-case problem.

 

[mounty2004]

I have the same problem with my 2004 mountaineer. But it happened while towing our camper with a new wd hitch. Oil sprayed out the breather tube, very burnt smell. Got vehicle home, rebuilt front diff with all new bearings, went to get camper and it started to smell before we got there and it happened again pulling camper home. Now we are contemplating the front diff again and replacing the viscous clutch. Thought about a used transfer case but dont know what shape that would be in.

Very interested in your results.

Hi. I got the same problem with my mountaineer 2004 v6. Oil came out from front differential breather and it smelled like a natural gas. Also smoke appeared underneath (could be the gear oil crawled to the muffler). Then I brought it to a workshop and they noticed that the front diff. oil was almost gone and they filled about 10 pumps of gear oil.
1.How could the front diff. oil almost disappear and flush out of the breather. I have it "C service" last July 2, 09.
2.Why so much pressure build up inside the front diff?

Can anyone help me please.

Thanks.

 

[mounty2004]

It's been raining all week, so I just got tired of waiting for it to stop and pulled the front shaft. It's parked on an incline right now and it's not moving. I even tried to push it, and it just bounces back like it normally would. I'm assuming this means the viscous coupling is indeed shot?

This would sure explain a lot!

Hi Shane91Explorer. So did you change the viscous coupling? Did the pressure build up on front differential and oil going out of the breather finally stop? Could this be the solution to the front differential problem? May I know what procedures you have done so I can suggest it to my friend mechanic.
Thanks for the info. Sure it will help a lot.

 

[mounty2004]

Hi. I took off the front drive shaft and change the differential pinion seal, front axle seals and my mounty is working well. Since I dont go to the desert and we dont have snow here in saudi arabia might as well drive as 2wd.

 

[howellma]

i replaced the viscous coupling and we rebuilt the diff with new bearings and reduced the backlash but the gears didnt look good and it has a high spot. I bought an infrared temp sensor and drove it and the front diff is definately hotter. Too hot! it hit 251 degrees towing camper at 55mph. I am going to have the gears replaced at the end of the month with new OEM gears. After that there isnt much left to replace to cause it to heat up. Rigt now we are living with the noise till we get it replaced.