Getting rear diff rebuilt, but told entire driveline should be rebuilt too

[MikeCA]

I need a rear driveshaft rebuilt on my 04 ltd, which is alright, I plan on keeping the truck for a while, but what I've also heard (not from the shop but another mechanic) is that unless I rebuild the entire driveline the rear diff will blow again prematurely.

Am I heading into a world of trouble here? Any truth to this?

Which fluid do you guys recommend, and any additives?

 

[Reverend Greg]

Any time a mechanic tells you a story like that take it with a grain of salt. Maybe a whole box of salt.
Unless that person is beyond reproach, I would only replace the broken parts.
Just like a car salesman, a mechanic isn't trying to do anything but put a meal in front of their family.
Greg

 

[MikeCA]

Just to be clear, this wasn't the shop doing the work, it's a buddy who used to work for Ford as a mechanic. He is of the opinion that unless the driveline is rebuilt diffs on the Explorer will fail prematurely.

Has anyone heard of this before? I'm just covering all of my bases.

 

[dubbio]

id kind of expect the next weakest link to fail before a rebuilt unit would. if the rear end is rebuilt i'd expect the axles or the universal joints to give up before the differential would need to be revisited.

 

[MikeCA]

Hmm. Ok, so I should get the u-joints done at the same time, you're saying? Probably makes sense to do a little bit of preventative maintenance.

I expect the tranny to go at some point, too. It's got 125k on the original. Front diff seems alright for now.

 

[dubbio]

if it were me id just have the differential done, maybe the rear wheel bearings, i think they literally have to pull every last bit out of the rear to get the differential out so the bearings would be right there to be replaced.

my old explorer had 250kmi on it and never had a cv or universal problem, and it had the original transmission still going. id definately look into installing an external transmission filter to help prolong the transmissions life.

 

[MikeCA]

Ok, I'll get the bearings done. Might as well.

For that tranny filter, are we talking an involved job or something relatively straightforward?

Thanks!

 

[dubbio]

its relatively simple, should still be a write-up about it on here if you search for it. basicaly its a remote oil filter mount, but you splice it into the transmission cooler lines. before the cooler would be best so it catches stuff that could eventually clog the coolers. you just to make sure you get the direction the fluid is going right so you dont hurt anything. usually you can do this by unpluging the ignition coil, disconnecting a line at the cooler and placing a baggie over it, then crank the engine shortly. the baggie with the fluid in it will be coming from the transmission and you can establish the direction of flow from that. just make sure the flow from the trans go into the "in" on the remote filter housing. mount the housing somewhere you change the filter easily, i changed the filter everytime i did the oil change and just added a quart of atf to keep the level correct.

 

[MikeCA]

Nice. I appreciate that and wilk look for the write up.

 

[wbw11]

My rear end gears had a whine for as long as I owned the vehicle. Eventually they started making clicking sounds at low speeds and we're making terrible vibrations. My mechanic told me to go ahead and replace the entire driveline including the rear wheel bearings. I was told I could have the gears rebuilt but my mechanic told me he could only guarantee that that would last me another year. If I remember correctly without digging into the file cabinet, the whole job cost more than my engine replacement.

 

[MikeCA]

It's an expensive job, for sure. I fully expect to have the full shabang done on that thing including replacing the bearings as they'll likely be contaminated. I'm not looking forward to the ding, but it's a hell of a lot less money than buying another vehicle.

Sometimes you just have to love what you've got and not go looking for trouble elsewhere, I guess.

 

[blue_goose]

How bad is everything acting up? is the diff humming or grinding ect like one of the previous posters said? In mine I bought it with 87k on it and the diff hummed first time I drove it, was louder than the road and wind noise but not terrible. Attempted the rebuild near 100k and after starting it realized what I was in for. went to the local small town dealership for advise and actually talked to a good tech. he said "I did one before, never again! don't bring that here, I don't want to touch it. keep changing the fluid and it will last as long as you can take the noise." I took his advise, put everything back together and I change the fluid every 20k or so. Now about 200k and its no worse than it was at 87k that I can tell and my vehicle has a pretty tough life (towing, hauling over GVWR, off roading, submerging it many times and I can see fluid leaking out the diff but just ignore it and keep changing the fluid).

As for the rest, these drivelines are surprisingly tough (except the tranny). I replaced my u joints and bearings as they went bad so that's a good idea but after all my abuse my cv's are original.

A tranny cooler is ok, but if you monitor the temps your just as well off. I have 3.55 gears (no tow package) and the only time mine gets above 210 is on a looonng mtn pass (4k feet, 2k feet it does ok towing or not). either way, one of the 2 is a definite must to make last.

Good luck, let us know the outcome!!

 

[MikeCA]

Thanks, Blue_Goose.

So I've taken a bite from the infamous apple tree and am throwing about 1/6th of the value of a new Explorer Ltd into the undercarriage. I figured why not, I'll keep this truck for several more years and even though the repairs are costing an arm and leg it'll be good for a while since it's only at 120k with a near-mint exterior and mint interior (knock on wood).

The rear diff was in bad bad shape, but you're right Blue, it wasn't causing unlivable upset unless I drove above 60. Regardless, it was causing rumbles and grumbles that I started to get irritated with.

I took dubbio's advice and will be getting the rear bearings replaced. They were in bad shape as well.

Of course, once that was all checked out we determined that the entire rear break assembly was shot with major rust issues. So new everything will be installed there as well.

I also had the tranny checked, and surprise surprise, metal shavings come in hot and the fluid looked like something out of a can of Campbells Soup. Add a tranny rebuild into the fray.

It's been a tough day on the wallet but this is all a hell of a lot cheaper than buying another truck (I sure as hell hope).

I'll keep everyone updated on how things progress but it doesn't look like I'll be getting her back until mid-week next week. I'll be taking a peek at the tranny innards on Monday. I'll try to remember to snap a photo.

 

[MikeCA]

Actually, I've got a question for you guys. The tranny shifts perfectly, there's nothing wrong with it to be honest, but checking the filter there was quite a bit of shavings and like I said, the fluid hadn't been done in a looooong time. There was also a layer of dark grey metallic film over the pan.

Should I just get it cleaned/serviced, and put back in to keep it going until it completely clunks out? Rebuilding the damn thing will cost an arm and leg as every car owner well knows.

I'll snap a photo Monday morning if that'll help.

 

[MikeCA]

I made a separate thread for the tranny at: https://www.explorerforum.com/forums/showthread.php?p=3488674#post3488674

 

[blue_goose]

Actually, I've got a question for you guys. The tranny shifts perfectly, there's nothing wrong with it to be honest, but checking the filter there was quite a bit of shavings and like I said, the fluid hadn't been done in a looooong time. There was also a layer of dark grey metallic film over the pan.

Should I just get it cleaned/serviced, and put back in to keep it going until it completely clunks out? Rebuilding the damn thing will cost an arm and leg as every car owner well knows.

I'll snap a photo Monday morning if that'll help.

I would do exactly that. Don't flush it, just change the fliud and filter and call it good. I would change the fluid every 10k for the next 30k so you can slowly get new fluid in there. Many people have over 200k on their original tranny (mine included), theres no telling how long these will last.

And your diff sounds like it was in rough shape, rebuilding will give you good peace of mind. Another thing to consider is a 04-05 diff from a junk yard, those years seem to be better and may be cheaper than a rebuild.

 

[MikeCA]

Thank you.

I think for the front diff if it ever goes I'll do just that. Fronts are usually in good shape at junk yards.

 

[fireball 440]

I would do exactly that. Don't flush it, just change the fliud and filter and call it good. I would change the fluid every 10k for the next 30k so you can slowly get new fluid in there. Many people have over 200k on their original tranny (mine included), theres no telling how long these will last.

And your diff sounds like it was in rough shape, rebuilding will give you good peace of mind. Another thing to consider is a 04-05 diff from a junk yard, those years seem to be better and may be cheaper than a rebuild.

My 2005 has a bad rear diff.

 

[Many3rdgens]

Can confirm that 2004 was no better. My 04 Explorer that we got new was rebuilt twice before 75k miles. It is now quiet and nearing 300k in my in laws care. My 04 mounty sounds quite nasty but I am in no hurry to repair it. I replaced the 02 diff in my father's explorer and took the opportunity to replace both axle shafts and rear wheel bearings. Glad I chose to do the shafts as one of them fell apart when pulled out and where the seals ride on it was all chewed up. The rear wheel bearings are an "every hundred K" thing on these anyhow. Nothing other than a U joint to worry about after all of that.

 

[MikeCA]

Why do the rears bearings wear out so fast?