[Buckeye12]

Does anyone happen to have the part number for the "full" plug? Closes thing that I've found is Part# W707919-S437 it looks close but don't think it's the right one.

Just bought a 2013 Fusion Titanium AWD and used this post to attempt to tackle the job. Transmission and PDU went great and then RDU was all down hill. I used a set of gearwrech torx bits that insert into a 12mm wrench and when removing all of the teeth in the plug broke off. The torx bit ended up being stronger than the teeth of the plug which was not expected. I was able to touch up the outside with a grinder, weld a nut to the existing plug and break it loose. Looking in all of the ford diagrams I can find and they don't specifically call out the part number for the replacement "full" plug.
Fill plug came out just fine.

 

[bbf2530]

Hi Buckeye. If no one can give you an answer here, simply stop by your local Ford Dealership's Parts Department and ask them for the part number and cost. Then you can have them order it or use the part number to order it somewhere else.

Good luck.

 

[Buckeye12]

Unfortunately the Ford dealership was no help on this one. According to their system all 3 plugs call for the same part number (full,fill,top) but only the top/full plugs are the same and the fill plug is larger. Looks like a generic 3/8" NPT plug is what I'm going to have to go with.

 

[maydk65]

Took my FFS in this morning to one of the local Ford Dealers to get RDU Fluid Change (40K Miles) and was told that this unit was not serviceable and that their service manual said they would have to take my rear end apart to change the fluid.
I just shook my head and left. This is the same dealership I had to get under the car and show them how to do PDU fluid change.

 

[metroplex]

I'm not sure why some the Fusion Sport owners are getting black fluid out of the RDU, but in my SHO when I replaced the PTU fluid (which was black) the RDU fluid looked almost new. I've never had a RWD vehicle where the differential oil would turn black - even when I changed it at 50k miles or so the oil would always look clear unless I went deep water fording.

 

[EdJenner]

2014 AWD Titanium

I finally got around to this at 65k miles. I have been checking it, it finally looked dirty enough to buy a pump and change. It was pretty dark - like the pics here, but seemed otherwise fine.

Ford 'schedule' is absolute BS. The PTU fluid was black at 30k miles. The transmission is rated at 100k miles (do not wait this long unless you are going to ditch the car). However, I also read somewhere that 'lifetime' for Ford is 100k miles.

The garage said they changed the trany fluid at 35k, but at 65k it was also black (so I assume they did not change it). I am wondering if original fluids do tend to go black? I mean I'd rather change tranny every 30-40k, but black at 65k. PTU black at 30k? I have heard it gets hot, so I just change it every 2 years of 15k miles - basically every other oil change for me.

Anyway, garages and Ford maintenance schedule can kiss my ass. The car is great, I want to keep it. Everything except the rear diff is trivial to replace, and the diff just needs a pump assuming you can get the level plug out (I did, it was also tough and I broke 1/4" spanners too). Just do it.

 

[EdJenner]

According to the manual this is completely unnecessary.. I think y'all just do this stuff for fun..

Ford and the manual are complete BS if you really want to keep the parts in good condition. Ford is doing this to reduce the 'maintenance cost' of their vehicles. Yes, the parts will probably all last Ford's 'lifetime', which is 100k miles without changing any fluids.

 

[Shawnski]

I’ve experienced and also heard from many Ford owners and transmission repair shops that brand new Mercon LV turns brown and smells burnt as soon as it heats up. I hate it because I grew up sniffing transmission fluid (that didn’t sound good!) to check if a car was well cared for. I wouldn’t trust that stuff to go more than 30k and it’s a relatively inexpensive preventative to just change it regardless of Fords schedule. My experience with the PTU and RDU has been pure good luck; every time I’ve had it changed, it was like new. My dealership mechanic says they’ve had Explorers and Escapes come in with 30k on them and malfunctioning PTUs that have fluid as black as tar. He says they don’t get many Edges at all into the bays, but they seem to be better.

 

[bbf2530]

"...I grew up sniffing transmission fluid (that didn’t sound good!)...

Hi Shawnski. Now that was funny! And well worth the 10 seconds of my like it took to read!

 

[Engineer]

I’ve experienced and also heard from many Ford owners and transmission repair shops that brand new Mercon LV turns brown and smells burnt as soon as it heats up. I hate it because I grew up sniffing transmission fluid (that didn’t sound good!) to check if a car was well cared for. I wouldn’t trust that stuff to go more than 30k and it’s a relatively inexpensive preventative to just change it regardless of Fords schedule. My experience with the PTU and RDU has been pure good luck; every time I’ve had it changed, it was like new. My dealership mechanic says they’ve had Explorers and Escapes come in with 30k on them and malfunctioning PTUs that have fluid as black as tar. He says they don’t get many Edges at all into the bays, but they seem to be better.

Aha! Well that explains a lot.

(ducks and runs)

 

[EdJenner]

I’ve experienced and also heard from many Ford owners and transmission repair shops that brand new Mercon LV turns brown and smells burnt as soon as it heats up. I hate it because I grew up sniffing transmission fluid (that didn’t sound good!) to check if a car was well cared for. I wouldn’t trust that stuff to go more than 30k and it’s a relatively inexpensive preventative to just change it regardless of Fords schedule. My experience with the PTU and RDU has been pure good luck; every time I’ve had it changed, it was like new. My dealership mechanic says they’ve had Explorers and Escapes come in with 30k on them and malfunctioning PTUs that have fluid as black as tar. He says they don’t get many Edges at all into the bays, but they seem to be better.

Thanks for that comment. So maybe the Trans fluid did get changed, mine did not smell burned. I will check it myself in 10k, good to know.

 

[Wojtas]

Took my FFS in this morning to one of the local Ford Dealers to get RDU Fluid Change (40K Miles) and was told that this unit was not serviceable and that their service manual said they would have to take my rear end apart to change the fluid.
I just shook my head and left. This is the same dealership I had to get under the car and show them how to do PDU fluid change.

😆😆😆 haha.
on the one hand it is ridiculous and on the other hand it is very sad that you can hear it in the Ford Dealership. That's why it's best to do it ourselves.

Does anybody of you took off the cover of Rear axle to clean it. I saw on youtube that one guy did it for one of the Ford. What do you think about it?
Are the draining the fluid and just pump the new one will be sufficient?

 

[LeVeL]

I'll need to pick up an extractor and a pump, already bought the fluid. What's the strongest T40 out there? I don't have a lot of faith in mine holding up, to be honest...

 

[Flew]

I'll need to pick up an extractor and a pump, already bought the fluid. What's the strongest T40 out there? I don't have a lot of faith in mine holding up, to be honest...

I used a Wera T40. Very pleased with Wera tools overall.

 

[metroplex]

So the factory service manual procedure for the RDU fluid change just calls to fill it 3mm below the rear fill port. It has nothing about removing the side plug.

That said, the last 2 times I changed the RDU fluid on my Fords, the factory fill always looked fine and it just seemed like a waste of time. I have 25k miles on my Fusion Sport and was thinking about changing the fluid, but I'd have to clean my vacuum evacuator out just for this lousy 0.5 qt change on a RDU where the factory oil probably looks good anyhow.

 

[metroplex]

I did mine at 32k.

We have 1 fill and one full level plug. The Front T40 plug is for the fluid level, the rear 3/8" plug is for sucking out the fluid and filling. If you fill until the fluid comes out the rear plug, the RDU will be over filled.

I can't for the life of me understand why Ford didn't have a drain plug installed.

The RDU uses 75W-80, the Amsoil 75W-90 (Red top) meets the specs and you will use about 1/2 a quart.

The PTU uses 75W-140 (Black top), and you need almost the whole quart bottle. So you are stuck buying 2 bottles anyways.

Maybe this was covered before but where did you see 75W-80? Ford's rear differentials have traditionally been either 80W-90 dino or 75W-140 synthetic (the former for regular grocery getters or slower towing/HD applications, and 75W-140 for faster HD applications Police Interceptors, Mustangs, etc...)

Ford service manual and owner's manuals both state 80W-90 for the RDU.

Also looking at the photo from the first post, the oil looks black in the bottle but how did it look when wiped off onto a white paper towel? I bet it is almost clear with only some mild coloring. If it stains the paper black like ink, then it'd be burnt (like the PTU fluid from a pre-2017 3.5/3.7 PTU unit ala Explorer/SHO). But all of the RDU/rear-diff oil I've seen used at 30k miles has been relatively clear on a paper towel, but looks "dark" like that in a bottle.

Also, that side plug is not specificed as a fill port/suction port in any of the guides. Seems like extra work. Maybe easier to extract the fluid though from the side as you can slip the tube possibly easier towards the lowest part of the "sump" with a vacuum extractor.

 

[metroplex]

I just did the RDU fluid change on my 2017 Fusion Sport. A slim 3/8" ratchet isn't needed, there is actually quite a bit of room to access the fill plug. Looks like the CD4 RDU is an entirely different design from the D3/D4 RDU (Explorer/Taurus) which was MUCH tighter.

Removed fill plug and no fluid came out, was a PITA to get the right slim and flexible hose to fit into the RDU to suck out the fluid.

Filled with fresh 75W-90 Redline, about 660 mL and some started pouring out the port. Book/FSM spec is 615 mL.

IMHO - at almost 26k miles, the old RDU fluid looked brand spanking new. It was even amber through the clear evacuator hoses. Totally unnecessary to change and a waste of time/resources like the RDU oil in my SHO and Explorer. Both of those vehicles' original RDU fluid at 30k miles looked brand new as well. I've never absolutely had to change the rear diff oil in any of my older RWD Fords either at under 100k miles. And without a drain plug, this was just a messy job.

 

[metroplex]

So I got to change my dad's Fusion Sport RDU fluid for the first time. His was at 27k miles, mine (above) was 25k miles. I extracted his RDU and it seemed like it was less than half a quart. Nothing dribbled out when I removed the fill plug. The old fluid was darker than mine, much darker. Not pitch black but had some black flakes floating out but definitely not amber or newish looking.

So I wrote down what I filled the last time and started using the MityVac extractor to inject the fresh fluid (the big syringe thing) and got to 650 mL and nothing dribbled out. I kept going until about 790 mL when some amount flowed out of the fill plug. Very odd that his RDU took more fluid than mine. It could be that I wasn't able to extract all of the fluid out of my RDU but last I recall it was about the same maybe slightly more?

It reminds me of how much I hate having to change the RDU fluid in these Fords that don't have a drain plug, all because Ford wanted to save $0.10 by not having drain plugs.

 

[usednick225]

Well I had a chance to try out the new Quickjack and what better way then to change the RDU fluid.
I had a 3/8" T40 socket but as it's been noted here there is very little room to get to the T40 plug
Ran to Lowes and grabbed a T40 bit like the one pictured, ended up rounding off the wrench.
My plug is pretty much welded in.
I soaked it in WD40, tried heating the housing around the plug, nothing.
Resoaked it with WD-40, I'll give it a go at the next oil change or when I change the transmission fluid in a few weeks.

You ever get it cracked open? I’m struggling with this right now I got it soaked in penetrating oil. Calcium chloride does a number on my undercarriage.

 

[metroplex]

You ever get it cracked open? I’m struggling with this right now I got it soaked in penetrating oil. Calcium chloride does a number on my undercarriage.

Can you access the cover fill plug with the 3/8" square drive plug? That's all you need. Don't bother with that side plug. You'll need a fluid extractor and hose to suck it out the cover port, then pump back in the right amount. That's it.

Personally I wouldn't bother changing the Rear Diff fluid unless you have like 100k miles. That area doesn't get that hot and in the past on all my RWD Fords, the fluid still looked brand new at 100k miles. I changed the rear diff fluid on my Fusion Sport, Taurus SHO, and Explorer at around 30k miles and the fluid looked brand new.