Oil seals - is there any practical difference...

[Vintage Engine Repairs]

Whenever I buy seals from Stihl, they're always TB seals. Whenever I buy seals from the local seal supplier they’re always TC. Besides the obvious that one is metal outer and the other is rubber coated metal - for the application in OPE, is there any real advantage of one of the two designs?

Reference:

 

[Mad Professor]

I buy the stihl gasket kits that come with seals.

Less expensive than seals.

 

[president]

Whenever I buy seals from Stihl, they're always TB seals. Whenever I buy seals from the local seal supplier they’re always TC. Besides the obvious that one is metal outer and the other is rubber coated metal - for the application in OPE, is there any real advantage of one of the two designs?

Reference:
View attachment 1117721View attachment 1117723

Whenever I buy seals from Stihl, they're always TB seals. Whenever I buy seals from the local seal supplier they’re always TC. Besides the obvious that one is metal outer and the other is rubber coated metal - for the application in OPE, is there any real advantage of one of the two designs?

Reference:
View attachment 1117721View attachment 1117723

Tom I like the OD rubber coated one due to the positive sealing
quality of the seal pocket to seal interface of the neoprean

 

[Vintage Engine Repairs]

I buy the stihl gasket kits that come with seals.

Less expensive than seals.

Yeah that can be a great way to do it cheaper. Funny how that works out isn’t it…

 

[Vintage Engine Repairs]

Tom I like the OD rubber coated one due to the positive sealing
quality of the seal pocket to seal interface of the neoprean

Awesome, that makes a lot of sense. I use Dirko on the outside of both seals, but I do like the idea of the rubber too.

 

[Hulpio]

I'm wondering this same issue too. My current project old Jonsered 535 had TB style oil seals and the ones I managed to buy are TC.
The reason for TB may even be easier or more forgiving installation during saw manufacturing process. Rubber coated ones you can not just hammer in, you got to have suitable tool to press them in evenly. Just my wild guess though.
What comes to other properties these rubber coated types are used in 2 stroke motorbikes with double HP per CC so I do not see an issue there either. Future will tell...

 

[WI_Hedgehog]

I wonder if the non-rubber exterior seals hold up to vibration better.

 

[Hulpio]

In any case those seals will get some Dirko HT between case and seal so we will see. I find these clamshell saws actually very easy to overhaul. Though I've ever played with split case saws.

 

[sean donato]

Any decent bearing, belt and seal company should be able to get you either version.
Having said that, I've seen both versions from the oem, especially on clam shell models. The tc seals better and takes bore deflection thrn thr to style. In reality you shouldn't need any sealant on any seal, even though most (including myself) tend to give the od a little smear for insurance.

 

[Vintage Engine Repairs]

Any decent bearing, belt and seal company should be able to get you either version.
Having said that, I've seen both versions from the oem, especially on clam shell models. The tc seals better and takes bore deflection thrn thr to style. In reality you shouldn't need any sealant on any seal, even though most (including myself) tend to give the od a little smear for insurance.

It’s been such a long time since doing a clam shell and got OEM seals that I totally forgot that they had rubber coating, thanks for the reminder.

 

[cookies]

Rubber coatings tend to harden or even shrink over time. They are easier to press in with less effort because the rubber deforms, I can often push them in with my bare hands. The rubber coated versions seal better in spots that have some corrosion, scratches, oil sludge, carbon buildup etc. I prefer this style for replacement when the engine or transmission is not disassembled, washed or being unable to use a proper seal driver or press.
Meatal clad seals are the stronger longer lasting version, they are less likely to pop out and seal better against the case by a stronger interference fit with the drawback of metal corrosion or dissimilar metal reactions if the seal coating is damaged. You should use a properly sized installation driver or press to install these straight and to the correct depth without distorting the seals outward metal face or the sealing lip will be distorted.
Some like to use sealants, I do not because the sealant may not bond to the case or the seal creating a leak, the sealant may not expand/contract at the same rate as the rubber or metal seals exterior causing a leak or even seal movement/looseness/dislodging. Lock tite for seals may be used to help overcome case damage or bore size irregularities to the available seals, thankfully I have not yet needed to use this personally...but life throws curveballs at every at bat it seems.

 

[Gratewhitehuntr]

The ability of a sealant to bond may have zero bearing on performance.
Teflon tape is a common "sealant" which bonds to absolutely nothing but is vital to the assembly of so many fittings.
RTV is the complete opposite, you might catch me "tooling" it in with a bit of emery cloth to guarantee adhesion.
In general, I prefer TB to TC, since seeing a few TC types which could be spun in the bore. Then again, they were quite old and tech has moved.
I'm surprised no one has brought up the types of 'rubber' listed by OP, as the properties vary so widely.

 

[Vintage Engine Repairs]

The ability of a sealant to bond may have zero bearing on performance, Teflon tape is a common "sealant" which bonds to absolutely nothing but is vital to the assembly of so many fittings. RTV is the complete opposite, you might catch me "tooling" it in with a bit of emery cloth to guarantee adhesion.
In general, I prefer TB to TC, since seeing a few TC types which could be spun in the bore. Then again, they were quite old and tech has moved.
I'm surprised no one has brought up the types of 'rubber' listed by OP, as the properties vary so widely.

I have only used Viton and nitrile.

 

[Gratewhitehuntr]

I'm sure you have an odd chemisty o-ring somewhere. Hint: they're color coded

almost some useful info in these links, the 2nd is pretty good for avoiding snafu aka prolapse plus it has citations and further reading at the bottom. I tell you this, o-rings are a rabbit hole. (I'm saying 'o-rings' but the discussion is about elastomer seals, same-same)

https://www.globaloring.com/oring-colors/
https://www.thomasnet.com/articles/hardware/o-rings-material-makeup/

 

[Hulpio]

Deep groove ball bearings like ones used in saw cranks should not get much hotter than 120C/250F. NBR oil seals tolerate 120C for some time. FKM copes with high temps better and can handle 160-170C. I will see if I can attach temp probe somewhere close to oil seal. Hopefully I can since this kind of data is interesting.

 

[Chevboy0167]

https://advanced-emc.com/o-rings-in...eveloping problematic leak paths as a result.

 

[Chevboy0167]

https://www.aagaskets.com.au/PDF/CrankshaftSealsAndSealingSurfaceWear.pdf

 

[Lightning Performance]

I prefer any seal with the steel case not coated. Less chance of heat damage on the pto side spitting out a hot seal. No chance of slicing the outer cover on the case and creating a leak. Don't think it matters on the flywheel side. The coated seal might be a better choice on clamshell engines. Most of those are coated except the replacement press in type.

 

[Gratewhitehuntr]

https://www.aagaskets.com.au/PDF/CrankshaftSealsAndSealingSurfaceWear.pdf

this article reflects something I'd always suspected but never seen mentioned
the seal creating heat via friction

On a related note, this might be useful information if you own something made of elastomer
While working on an old motorcycle I came across the idea of re-plasticizing rubber carb boots with a mix of methyl salicilate, xylene, and ethanol. It worked EXCELLENTLY! Pro tip, use a ziplock and vacuum.
Note, that is the bulk recipe. Be very careful about contact time or your rubber may look like a black prolapsed

There is a product you can purchase to test this concept, perhaps on your motorcycle seat or other elastomer.
I tried it on everything no damage, it even worked to aid penetration of hard plastics by dye, such as restoring faded auto body trim from grey to black. It seems to sorta work even when it doesn't, nice minty smell, no skin irritation. OMG now I want to try it on pleather. If blended with Armor All on a rag, it's still very good.
https://www.amazon.com/Sonax-03401000-Rubber-Protectant-GummiPfleger
Dupont makes one too but I have not tested this one, YMMV.
https://www.amazon.com/DuPont-Rubber-Saver-Gasket-ConditionerSOMEONE should test this on crankcase seals in situ, like a Poulan 3400 not worth restoring properly


This brand was tried while the Sonax was out of stock, it's less concentrated and I'll not buy it again. The dilution might be OK if you were being cautious or giving to the wife to use. Rather than buying this pre-diluted (with gawdknowswhat) IMHO better to dilute the Sonax with your own favorite product (Armor All?) https://www.amazon.com/nextzett-91480615-Gummi-Pflege-Rubber