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rear axle seal leaking 78 4WD 150

Well thanks to everyone's help I was able to rebuild the rear brakes on my 4WD 78 f150. I had a few hours of relief and then noticed a leak on the inside of the tire. I figured the new wheel cylinder had blown, but nope, its the axle seal and this is the same leak I'd assumed was a bad cylinder when I started. I'm looking on the bright side: now I have new brakes.
Maybe you guys can help be get started on replacing the seal. My shop manuals are all over the map and I can't figure out what the blazes they are saying.
Can I pull the backing plate and pull the axle and then pull the seal without special tools?
Do I need to get into the differential to disconnect the axles?
And there is a little breather valve. I'm thinking this might have gotten clogged and caused the problem. Does that sound likely.
Thanks, as they say, for your continued support.


jim in nc
 
Not sure on the seal, but if it's anything like chevy rears, it's just a pop it out with a screwdriver and push the new one in deal, after removing the axle of course. Yes you will have to get inside to pull the axle out.

What I can help with is the breather. I just 30mins ago pulled mine off, thought it was a bolt as it was solid. As soon as I pulled it off, I got a puff of air out of the hole. I read up on it and found out that if it plugs up, it builds pressure and will push oil out of any/all of the seals. I have a couple wet spots, so hopefully it will stop now that I ran a drill bit down through the vent and got it all clean. :)
 

smokey

Hitech hillbilly
Staff member
To pull the rear axle you need to pull the drum off
There should be 4 small nuts around the outside of the axle on a plate, remove those and the axle should slide out.
Pull the seal replace it and slide axle in.
No special tools needed.
 

LEB Ben

Arrogant A-hole At-Large
34,919
1,124
outside your house
^^^Agreed...and I'd also suggest a liberal amount of PBlaster on any bolt, makes life a little easier.
 

Fellro

Moderator
Staff member
On 9" axles, you don't have the c clips that require you to take the diff apart. If you did, you would never get it apart, as you can't get into the diff with the axles in place... But as mentioned, the 4 bolts that look like they hold the backing plate for the brakes also hold the axle retainer in. Take those out, and the axle comes out.
 
This is very good news

I'm looking forward to replacing these seals and getting back on the road. Now I'm wondering if that axle valve was the culprit. I'd noticed a leak beneath it some time back but I thought it was coming from the brake lines because they all meet at a little junction box that fits around the valve and I was focused on bad brakes.

Could I remove that valve and clean it, or blow it out, or soak it in solvent if it's not readily available at one of the parts stores ?
 
Thanks again you'all for your help

I thought I posted a response but then I didn't see it when I checked back. . . but I was saying that this is good news: not having to get into the differential or needing a puller etc.

But now I am wondering about this valve. Are they available at the parts stores and if not any ideas on how to clean mine out so that it doesn't let the pressure build again.

And I put regular gear oil in the last time: Well I put Lucas in the last time. I had money then, but I didn't ask myself if I had a limited slip and needed that kind of oil. How do I know?
 
I just took my vent off, cleaned out what I could with a pick and then ran a small drill bit through it a few times. Wash it out with carb cleaner/etc and it's done. I'm replacing all the brake hardware, and between that and this thread I've decided to go ahead and replace the seals while I'm in there too . I'd hate to get it all back together and have a leak, and the seals aren't that expensive considering I've already bought all new brake lines, cylinders, shoes, hardware, ebrake cables, drums, etc. :)
 
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valve, tubes, cables

Hey, KBrian. I've been checking around and the low down is to at least get a tube on those valves of ours, run a hose up higher then likely water level. One guy used a clear line so he could check it and a vw fuel filter on top.
Talk to me if you have any questions about your brake job. If nothing else get that spring removal and installation tool (just a foot long piece of metal with a bend and socket end for removal and hook end for installation). A friend loaned me his but they can be gotten for 6 or 7 bucks and you can believe they are worth it.
I'd be interested to hear about your adventures with that brake self adjusting cable (beware: there are two sizes).
 
Yeah, I've read that too on the hose. I'm nowhere near that point yet though. :p

I'm no stranger to brakes, so I'm in good shape. Check my thread for pix of the progress. Oh, and I have a really nice brake tool, it's on the floor in one of my pix. :)
 

BKW

Ford Parts Guru
1974/79 F100/150: Ford used two totally different axle seals in these trucks, The only way to discover which type it is...is to pull the axle.

One type is an axle seal/wheel bearing combination (D4AZ-1225-A or D4AZ-1177-A seal only).

The other is just the seal that presses into the axle tube (EOTZ-1S177-CA, replaced C9AZ-1177-A).

The rear brake hose has a brass block which has a hole in it. The rear axle vent passes thru the hole, threads into the housing.
 
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is it as easy as one, two, three . . . and, uh 4

Thanks and BKW, do you agree with Fellro, that I just undo those four nuts through the backing plate and the axle pulls out . . . no C clip in the differential to undo?
 

Fellro

Moderator
Staff member
The bearing/seal combos he refers to are what actually retain the axles. If you have ever heard of c-clip eliminators, it is the same principle. The bearing is pressed on the shaft, and that is what keeps it from coming out. if you had a c-clip in the pumpkin, you would have to have a removable cover, which you do not have on the 9" axle. So in order to pull the pumpkin out the front of the axle, you have to pull the axle shafts. There is no other way in short of a cutting torch. You might have to use a slide hammer to get the axle to actually come out of the tube though. Take a good look at the pumpkin area, and you should have the answer come to you, as there is absolutely no access into the center section with the pumpkin in place. C-clips like the 8.8 and the GM10 bolt rears have to be taken out with the diff in place, so they have rear covers that are removable.
 

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