Front differential fluid change + fill plug upgrade

[762mm]

So, I decided to do the front diff service today and change the original front diff fluid that's in there before winter (with 132,000 miles). As most of you know, there's no drain plug on the front diff (as opposed to the rear diff, which has one) and the only good method to do this without taking off the front cover is to suck all the fluid out through the fill plug!

For this, you will need a fluid suction pump. I bought a model which works on compressed air for about $15 on Amazon... and it worked surprisingly well. It came with the wrong coupler though, so I had to swap it for a "Milton type M" right off the hopper. Besides that, I was very pleased with the quality of the tool for the price.

Before beginning the procedure, I drove the truck for a few miles in 4x4 HI, so that the fluid would mix with the gunk/sediment in the diff and also warm up a bit, as it was 50 F outside (10 C). I then jacked up the front wheels and set the frame on 6 ton jackstands, just so the wheels are slightly off the ground and could spin freely, in case the bolts inside the diff were in the wrong position to pass the tube through to the sump and I'd need to spin the front wheels by hand... I actually did have to spin the wheels a bit later on.

The procedure took quite some time (15-20 minutes) and I had to empty the small tank on the tool several times before getting all 1.8 quarts of old fluid out. The old fluid looked and smelled nasty, plus it had a dark grey / gunmetal color to it.

Here are some pics of the procedure. Becasue the fluid was quite cold, the flow was very slow... but still better than taking that pesky front diff cover off, lol :









FordTech Makuloco's instructions video :

 

[762mm]

I also noticed that, unlike the rear diff, the front diff does not have a magnetic fill plug for some odd reason (FoMoCo trying to save 5 cents?). Luckily, I had one on stand by that I also purchased on Amazon for $5 a few weeks ago, as my transfer case has stock fill and drain plugs that are not magnetic either...

Anyway, I tried the magnetic fill plug in the diff and it fit like a glove... plus just to test it, I ran it in the old fluid and it immediately picked up some small specs of metallic gunk, confirming that it works as intended.


Here are some pics of the "upgrade" (I applied some teflon tape on the thread) :




New vs old :





Installed in front diff (using a 17mm, 12-point socket) :

 

[Black]

Have a link to the tool at Amazon?
I have a Griots Garage one man pneumatic brake bleeder that works for the job but is even slower than yours since it is designed for thinner brake fluid.

 

[762mm]

Have a link to the tool at Amazon?
I have a Griots Garage one man pneumatic brake bleeder that works for the job but is even slower than yours since it is designed for thinner brake fluid.

The tool I used is very common and if you're willing to wait, you can get a better deal ($10) on eBay, for example. It all comes from China, but the quality is surprisingly good. The cap and mechanism are CNC aluminum, which was a nice surprise... and the tank is a very thick, heavy duty plastic.

It is marketed under different names and different descriptions. Some call it a "brake bleed tool", where others call it a "fluid replacement tool". It works well for any application, though.

If working with diff fluid, in retrospect, I would recommend waiting for hot weather or to warm up the differential casing with a propane torch before extraction, to speed up the process. Similarly, I placed my two 75W90 1-quart bottles of new fluid into a pot full of hot water prior to pumping them back in with my mini manual pump. It made it so much easier! (I didn't do this when filling the rear diff and was pumping for 30 minutes, lol)


Here's the Amazon link:

https://www.amazon.com/Brake-Change...SXV0JBXWPFJ&psc=1&refRID=2J2QJW8JRSXV0JBXWPFJ

 

[dcsang]

Great post! I decided to proactively drain and fill transfer case along with front and rear differentials and got stuck here. My wheels were grounded and I had no success with a narrow tube. Is there a method to spinning the wheels to provide the clearance needed to get the tube deep enough into the case?

 

[07navi]

I am always on top of everything on my vehicles to keep everything working like it should but I will never drain my front diff. They spin about 1% of the time and changing the oil will do nothing which is also the reason for the missing magnetic plug........there is nothing to magnetize.

 

[dcsang]

Perhaps that is why there is no drain plug, and it makes sense. I don't know how the previous owner used the vehicle so for that reason I thought it couldn't hurt to change it. The rear fluid was in surprisingly good condition for 100K+ miles and I'm pretty certain it was never changed. Only the typical accumulation on the magnetic plugs.

 

[07navi]

Perhaps that is why there is no drain plug, and it makes sense. I don't know how the previous owner used the vehicle so for that reason I thought it couldn't hurt to change it. The rear fluid was in surprisingly good condition for 100K+ miles and I'm pretty certain it was never changed. Only the typical accumulation on the magnetic plugs.

I haven't read the manual on this but my Excursion didn't even take synthetic in the front and the rear went at least 100k miles before a change according to the manual. Your previous owner would have had to spend an awful lot of time off-road and even then the power would have been split in half with the rear plus it was all low speed. In all my years of being a mechanic I have never heard of a front diff wearing out that kept all of it's oil from day one.

 

[dcsang]

The 150K miles maintenance schedule calls for transmission fluid and filter, front axle fluid (4WD), rear axle fluid, transfer case fluid, and drive belt(s). I'm not there yet but have seen too many instances where the first fluid flush at a high mileage intervals coincidentally leads to component trouble or failure a short while down the road. I'm not referencing Ford trucks in particular but figure early service of these fluids over 100K miles couldn't do any harm.

A little persistence and wheel rotation provided the necessary clearance for a 5/16" O.D. tube with enough rigidity to avoid bending with minor resistance. I used a manual pump with clear vinyl tubing and 9" of the 5/16" tubing extending from the intake hose. This worked faster and more efficiently than all the videos I've seen utilizing compressed air extractors. I measured darn close to the specified 1.7L. The fluid was the same grey color seen in most of the available videos. Some believe that's due to water penetration and others attribute it to a grey marking compound Ford used on the gears from the factory. Either way, it was noticeably thinner than the 80W-90 replacement.



Now I just need to find a dealership that will change the transmission fluid since my local service departments refuse to do it until the vehicle reaches 150K miles. That's a different topic altogether.

 

[07navi]

The 150K miles maintenance schedule calls for transmission fluid and filter, front axle fluid (4WD), rear axle fluid, transfer case fluid, and drive belt(s). I'm not there yet but have seen too many instances where the first fluid flush at a high mileage intervals coincidentally leads to component trouble or failure a short while down the road. I'm not referencing Ford trucks in particular but figure early service of these fluids over 100K miles couldn't do any harm.

A little persistence and wheel rotation provided the necessary clearance for a 5/16" O.D. tube with enough rigidity to avoid bending with minor resistance. I used a manual pump with clear vinyl tubing and 9" of the 5/16" tubing extending from the intake hose. This worked faster and more efficiently than all the videos I've seen utilizing compressed air extractors. I measured darn close to the specified 1.7L. The fluid was the same grey color seen in most of the available videos. Some believe that's due to water penetration and others attribute it to a grey marking compound Ford used on the gears from the factory. Either way, it was noticeably thinner than the 80W-90 replacement.

View attachment 36781

Now I just need to find a dealership that will change the transmission fluid since my local service departments refuse to do it until the vehicle reaches 150K miles. That's a different topic altogether.

Why won't they do it with less than 150k ?