Why do oil seals fail

SDE · Mar 29, 2020

This one holds the gear oil into the bottom of the steering housing on a Farmall C. Is it wear on the seals surface? Is it that the spring that holds the seal against the metal surface, weakens over time and that it isn't able to hold it tight enough anymore? Is it the the seal hardens over time and then the spring isn't strong enough to collapse it down against the shaft? The shaft isn't worn, so is it all three or even something else?
TY
SDE

SVcummins · Mar 29, 2020

They get dry and hard with age

SVcummins · Mar 29, 2020

Mechanical failure from a bearing going out and letting the shaft ruin the seal . Overfilling the component with to much oil will blow the seal

old · Mar 29, 2020

They are just like we are as they get older things get stiff and do not move as they once did

Jeff B. · Mar 30, 2020

Several things. Heat and cold cycles and age eventually harden the rubber compound being used. It also slowly fatigues the spring behind the lip. Older leather lip seals dried up if they were allowed to sit for long periods, plus they simply wore out.
If you ever look at a National Seal size catalog, there are many pages describing lip styles and various rubber compounds to use depending on the application, rotation speed, and the type of fluid to be sealed.
Back when they first started using rubber seals in automotive applications, the material, Buna-N, I believe, worked well, but it hardened up after a few years. The newer rubber compounds they use today include polyacrylate and others that have a WAY longer life, and new ideas about lip designs have extended the efficiency of seals greatly. Contaminants in the fluid are also a factor in determining how long a seal will last.

MarkB_MI · Mar 30, 2020

The number one cause of seal failure is a loose or bad bearing. Replacing a leaking seal without fixing the underlying cause never works for long.

showcrop · Mar 30, 2020

Another major cause is dirt against the lip. My Ford 971 will go through PTO seals in 6-8 years. The shaft turns constantly and there is always some dust against it. The power steering cylinder seal doesn't even turn yet it constantly has dust against it as the shaft goes in and out. When I was into trail bike competitions fork seals were a problem even with a boot to protect them. We would lift the boot and put cotton underneath to catch the dirt and renew it after each ride.

Mike(NEOhio) · Mar 30, 2020

All of the above.

Steve@Advance · Mar 30, 2020

Steering gear seals are prone to leak anyway.

Dirt, shaft imperfections, bushing wear, all contribute. Typically the seals are a compact design, which makes the lip narrow, which limits the flexibility or travel of the seal as it wears and age hardens.

A common fix for manual gears is to use cornhead grease, a simifluid grease that is thin enough to not channel away from the gears, but thick enough to stay in with less than perfect seals.

ss55 · Mar 30, 2020

Age, wear, over greasing, too much shaft movement, the flexible material "dries out" and gets hard. A Farmall C tractor is now 68 to over 70 years old, if that is is the original seal it has greatly exceeded the 20 year intended design life of the tractor.

Corn head grease is often used when seals get bad.

dr sportster · Mar 30, 2020

Exactly it is almost always the wallowing around of a worn shaft eating any seals.

John T · Mar 30, 2020

Based on my farming and mechanical experience I've observed seals fail due to:

Worn loose bearings causing shaft wobble
Age and drying out and/or shrinkage
Long periods of non use
Rough, pitted, non smooth or non round shaft against which they are sealing

Im sure there are more, but this has been my personal experience

John T NOT a professional mechanic

fastfarmall · Mar 31, 2020

I changed mine on my B Farmall last year,the first time i changed it in 40 years, and the my Local IH dealer had it on hand, and wasn't to high priced!!

buickanddeere · Mar 31, 2020

Age, temperature, type of oil, type of seal and what contaminants in the oil.

Why do oil seals fail

SDE

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SVcummins

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SVcummins

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old

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Jeff B.

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MarkB_MI

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showcrop

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Mike(NEOhio)

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Steve@Advance

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ss55

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dr sportster

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John T

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fastfarmall

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buickanddeere

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