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Author Topic: 78 Rear Axle Seals - Why so difficult to seal?  (Read 2912 times)

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Offline 74WagonMeadowGreen

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78 Rear Axle Seals - Why so difficult to seal?
« on: March 12, 2012, 09:07:09 AM »
Back again with a seemingly ridiculous, but ongoing problem. On my 1978 Pinto with 52,000 original miles, I just installed the "correct" rear seals to replace the "incorrect" seals that leaked within two days of installation. I have installed many, some far more fragile, seals over the years so I really am not unfamiliar with all the needed care required to install them without damage. I know what happens if there is absolutely any distortion. Yes, the hard way! I also learned the difference between the very particular specs listed for the two different seals, each recommended for my application. Rear seal replacement should not be qualified as "brain surgery"!! However, mine are driving me crazy.

I initially replaced my rear seals with 3214 units per information given me by a seal mfg. Months later, when replacing the master cylinder and booster, I noticed both my NEW seals leaking all over. Since the time I had done that job I learned that although the number 3214 (National, Federal Mogul, etc.) seal is indicated to be the proper replacement, IT IS NOT!! According to dimensions, the inner diameter is listed around 1.3 inches... the true axle diameter at the contact point is 1.25 in. I also discovered that the CORRECT seal is number 3199, with a correct, 1.25 Inner diameter.

Has ANYBODY else encountered an ongoing problem sealing their axles? I inspected BOTH the seal surfaces, the housing and the bearings. All appears excellent, and at 52,000 there is no apparent wear in the bearings, which look, move and sound like new. Is there a superior seal recommended? Should it be necessary? Please let me know. Thanks!

Offline D.R.Ball

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Re: 78 Rear Axle Seals - Why so difficult to seal?
« Reply #1 on: March 12, 2012, 09:54:51 PM »
Did you check the surfaces with a straight edge or just eyeball them? I did not have any problem with my rear end seal change.What kind of rear end ? 6.75" or 8" rear end was it swapped etc. Like I said my parts store kit when right in, are you sure it's not brake fluid?Double check to ensure that you have the right kit IE 6.75" versus 8" etc.Check to ensure that you axles are not bent or the ends are not bent either.

Offline 74WagonMeadowGreen

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Re: 78 Rear Axle Seals - Why so difficult to seal?
« Reply #2 on: March 12, 2012, 10:57:19 PM »
Before I was able to log back in I thought about something... why in heavens name would two sets of seals, BOTH sides blow out so quickly, but sealed perfectly while the car sat and was not driven... I am thinking the differential VENT tube! The very next thing I will disassemble and make certain is clear is the vent... for all I know some mud dauber closed up the end of the pipe over the last 34 years!! It makes sense, as the seals are designed to hold back oil, but not really designed for high pressure, and that is what the vent prevents.

Offline dick1172762

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Re: 78 Rear Axle Seals - Why so difficult to seal?
« Reply #3 on: March 13, 2012, 03:06:07 PM »
Vent tube has a VERY small hole in it!!!!! Drill it OUT to at least to 1/8"(.125). Very easy fix. I use two vent tubes on all the race car I build. You can't over vent it.
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Offline 74WagonMeadowGreen

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Re: 78 Rear Axle Seals - Why so difficult to seal?
« Reply #4 on: March 20, 2012, 10:17:17 AM »
An excellent idea, and one I did (drilled it out to approx 1/8") when I pulled mine to inspect it. The vent size did look incredibly small, especially considering the tube that is run well out of water's way. There was a blob of old, gooey oil in it which cleaned out, but could slow down air travel dramatically. It appears that only one side blew, upon revisiting the underside more closely. I went ahead and bought a pair of Timken 3199S seals, and will replace the one that is leaking. Thank you for the advice, it is always better to have more than one head approaching a problem!

Offline mikerich1972

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Re: 78 Rear Axle Seals - Why so difficult to seal?
« Reply #5 on: November 04, 2017, 12:53:30 PM »
First, I want to say thank you for sharing this information!

I have a '76 wagon with just under 365,000 original miles (original engine!!). Had the rear rebuilt maybe 10 years ago due to pinion bearing slack and misalignment of the ring and pinion, causing excessive noise. Anyway, it's been fine until recently when it started dumping oil onto the rear brakes. I found the rear vent plugged and cleared that. replaced the rear oil seals with the recommended #3214. Well, it's now about 30 days later... and more leaking!

Because of your information here, I just ordered a pair of #3199's on EBay and will swap them when the weather allows.

For your further information, this is what I found;

3214's dimensions are listed as:  ID:  1.625"    OD:  2.437"  Thickness:  .468"

3199's dimensions:                    ID:  1.25"      OD:  1.96"    Thickness:  .256"





1976 Pinto Wagon 2.3L
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Offline dick1172762

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Re: 78 Rear Axle Seals - Why so difficult to seal?
« Reply #6 on: November 04, 2017, 01:50:09 PM »
If you had the wrong seals, it would not have taken 30 days to leak. I've always tried to use the brand @#$% Rawhide. Can't remember the rest of the name. Those seals were almost as good as the factory seals which were much better than aftermarket seals. Seals are one item the factory's try not to cut corners on.The two seals you show are a mile apart on size. Try to stay away from seals from China. Sadly most are from China today. Try e-bay but be careful on what you buy. Sorry but I don't have a clue on part numbers for the right number. Send a pm to Tigger as he lives up near you in the NW.
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Offline 65ShelbyClone

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Offline Reeves1

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Re: 78 Rear Axle Seals - Why so difficult to seal?
« Reply #8 on: November 23, 2017, 07:19:54 AM »
Before I was able to log back in I thought about something... why in heavens name would two sets of seals, BOTH sides blow out so quickly, but sealed perfectly while the car sat and was not driven... I am thinking the differential VENT tube! The very next thing I will disassemble and make certain is clear is the vent... for all I know some mud dauber closed up the end of the pipe over the last 34 years!! It makes sense, as the seals are designed to hold back oil, but not really designed for high pressure, and that is what the vent prevents.

Seen this many times. Had one hose that 125 lb pressure wouldn't blow the mud out. New hose & all was good after that.
It's now the first thing I check on a vehicle showing a seal leak.

You can get jobber breather caps for the hose.....

Offline dick1172762

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Re: 78 Rear Axle Seals - Why so difficult to seal?
« Reply #9 on: November 25, 2017, 10:05:53 AM »
Chicago Rawhide is the right name. VERY good seals and more.
Its better to be a has-been, than a never was.