Changing your differential fluid?

[Pakrat]

This is probably going to seem a stupid question to some, but any tips or tricks for doing this easy and or efficiently? I mean, I know it's just removing one simple plug on the pumpkin, but the correct level should be even with the bottom of the plug, so does that mean you are expected to jack the back up to drain out as much as possible and then measure what you remove and replace that same amount with new, or again to the bottom of the plug when level? That is the only common sense approach I see shy of using a syphon. Also, what's the best replacement diff fluid to use? If the age and brand of exisiting is unknown and fully draining and flushing is not possible, then is brand mixing an issue, like say with antifreeze or brake fluid etc....? I'd like to tackle this in the fal, so any insight would be greatly appreciated. The stupid repair manuals basically only say remove plug, drain and replace. Gee, thanks alot oh great and insightfull sensei.

 

[Pakrat]

After battling with the search function in between 45 second waits I finally found this not too old thread on the subject.

http://forums.stangnet.net/showthread.php?t=467710&highlight=changing+fluid

Despite what it says, I have to believe replacing the bulk of the fluid is better than not doing it at all.

 

[Max Power]

In 25 years of working on cars, sometimes for a living, I have never seen a Ford non-posi differential failure of any kind that was fluid related.

If for some reason you feel you need the exersize, remove the carrier and drill and tap a drain plug. Remember when choosing location that the housing is often used as a jacking point.

 

[VictorII]

This is probably going to seem a stupid question to some, but any tips or tricks for doing this easy and or efficiently? I mean, I know it's just removing one simple plug on the pumpkin, but the correct level should be even with the bottom of the plug, so does that mean you are expected to jack the back up to drain out as much as possible and then measure what you remove and replace that same amount with new, or again to the bottom of the plug when level? That is the only common sense approach I see shy of using a syphon. Also, what's the best replacement diff fluid to use? If the age and brand of exisiting is unknown and fully draining and flushing is not possible, then is brand mixing an issue, like say with antifreeze or brake fluid etc....? I'd like to tackle this in the fal, so any insight would be greatly appreciated. The stupid repair manuals basically only say remove plug, drain and replace. Gee, thanks alot oh great and insightfull sensei.

I have a cheap hand pump I got from Kragen. To replace the fluid, I just drive the car until the fluid is hot, then pump it out. Then replace it with what is required. I have a built 8" Tractionlock so the plug is in the center (sort of) of the rear of the housing. I don't know where it is on the 9" units. If you have posi (tractionlock), remember that you probably will need an additive. If it is Tractionlock, it's cheap, about $7.95 and best bought fromthe Ford dealer. On the 8" units, procedure is to fill to the bottom of the plug so you have to do it with the car level.

 

[Pakrat]

In 25 years of working on cars, sometimes for a living, I have never seen a Ford non-posi differential failure of any kind that was fluid related.

If for some reason you feel you need the exersize, remove the carrier and drill and tap a drain plug. Remember when choosing location that the housing is often used as a jacking point.

So are you saying I should not worry about changing the fluid then?????

 

[mustangdave]

I got a 9" from a junkyard and tried to use a Mighty Vac kit to remove the fluid: no dice. The hose hit so many components in the rear end that I was only able to extract a few ounces. But what I saw was disturbing: very, very black gritty feeling fluid! I still have no answer to the problem other than driiling a hole. Upon further inspection, I found the axle bearings were shot and replaced them. This might account for the nasty fluid. I think I will try the unit anyway as is; if it it doesn't work, all I've lost is labor and a bunch of aggravation.

 

[67GTA-FB429]

Pak: Get a little hand pump, like a brake bleeder setup, pump it dry and add new. OR take it Jiffy lube and have them do it.

 

[Hack]

Yeah either a brake bleeder, or your auto parts store should have a cheap little pump for filling the diff. You could use that for pumping it out.

Or you could pull an axle and jack up the other side of the car.

Wouldn't it also be pretty easy to pull both axles, drop the drive shaft, and pull the chunk? Then you could get it spotless in there. Once every 40 years or so probably isn't overkill on that sort of maintenance.

 

[Max Power]

pak, I wouldn't worry about it unless it is giving you problems.

Those little pumps are difficult to use in that you can't get the hose past the internals and down near the bottom of the housing.

The only way to do it right is to remove the carrier, really, and that is as much work as replacing failed components.

In short, I wouldn't worry about it.

 

[Pakrat]

Nope, no known problems anyway so hey, fine by me, thanks. I like crossing things off the list before I even get to them.

Just out of curiosity, how would those jiffy lube boys go about it anyway? Pump and replace also? Just curious. It really does seem that it should naturally have a plug at the bottom to drain it instead of just that one on the front, but I guess if it's the complete opposite of changing your motor oil, then it really isn't necessary and likely why it ain't so easy to do. I'm pretty sure it was done in the early 90's (about 6,000 miles ago) by the PO when he wen't thru all the other stuff anyway so I guess it's no biggie. Maybe I'll just make sure it's as high as the bottom of the plug then and top it off if not. Thanks.
Pak.

 

[WORTH]

So are you saying I should not worry about changing the fluid then?????

It's always a good idea to change fluids, fluid is a hell of a lot cheaper than PARTS. . If the car is a keeper pull it apart and drill and tap a drain hole.

 

[Hack]

It's always a good idea to change fluids, fluid is a hell of a lot cheaper than PARTS. . If the car is a keeper pull it apart and drill and tap a drain hole.

Is it difficult to drill and tap cast iron? I would think so, but then I've never tried. Any tips?

 

[raph130]

*

 

[Max Power]

He would drill to drain, not fill.

While fluid is cheaper than parts, what fails in diffs, when they fail, which is not often with ford 9 inchers, is usually bearings. Bearings are cheap. The PITA here is the labor.

If I had a 9 inch out of the car and spotless, I would drill a drain plug into it. Other than that, I wouldn't sweat it.

Besides, I think Pak has bigger issues right now!

 

[Pakrat]

So true, so true.