Crankshaft seals

[Jens]

My 20/2 has lip seals to keep the crankcase oil in. Two questions:

1) Should these seals be automatically replaced

2) There was a fairly substantial load of heavy black grease on the inside of the seal where it didn't seem to make much sense for being there. Is this grease required and if so what should I use when I reassemble ?

[mobile_bob]

if you can reuse the seals, do so
no reason to replace them unless they were leaking, or have been removed, or are torn or otherwise damaged.

as for grease

i have used standard chassis lube, the stuff that comes in a grease gun tube, clear body, either red or blue tinted
it is compatible with any motor oil and will stay put until engine oil washes it out, thus assuring lubrication of the affected parts.

and yes i use it on rod, main, cam and other bushing and brgs as well.

unlike lubriplate (the white assembly lube) it will not harden over time, and block oil passages.

fwiw

bob g

[Ian]

Maybe it is just the way I am - but I would replace the seals. They are very cheap and standard sizes so are likely to be in stock at any bearing supplier.

The benefit as I see it is that the replacements are likely to be a more resilient material than the Indian original ones and, being new, will be softer and easier to work with (until they have been in use for a time and hardened up).

However, if they cannot be replaced - it is not a big deal to use the original ones.

Seals do not REQUIRE any grease but a small amount on the mating surfaces will help you with refitting and HELP (but not guarantee) to maintain the seal lips to stay in good condition during the assembly procedure.

Regards,
Ian

[Crofter]

Replace them for cheap insurance; take a chance only when you have no other option, would be my advice. There is too much chance of having stretched or damaged the seal lips in the process of removing and reassembling the bearing housings. The seals get stiff and less resilient to keep their squeeze on the shaft. The lips also wear and if the seal is the type with the fine wound garter spring that can corrode / break.

The seal will be a lot easier to change with the housings off than trying to pry them out after having to haul the flywheels off if they do leak. I think the twin may be more leak prone than the single because of crankcase pressure.

[playdiesel]

I am of the crowd that says, they are cheap, replace them but there are people who do otherwise anmd get along fiine. The part that bothers me with these engines is having to slide them so far on and off those long shafts and the associated nicks, bumps, keyways etc. A couple tips are to check the shafts carefully imperfections and run a file down the top of the keyways to knock back the knife edge left there by the Indians. If you choose to replace the seals leave them out until you have the housings installed, rotate them as you slide them and use any #2 grease handy to lube them or even oil if your planning to start the engine soon.

[mobile_bob]

another thought came to mind

most seals of this class have a small coil spring used internally to tension the seal lip down onto the shaft

the reason for the grease is to assure that the spring stays inside the lip as the seal is driven in, some of those springs
have a nasty habit of popping off the lip (and of course you may not know it until it leaks), so packing grease inside that
area cushions the spring and keeps it in place.

likely why you see grease packed up in there.

back in the day of this sort of seal being used in wheel seals it was very common to pack them full of grease to keep the spring
in place, and it is still done today for rear end pinion seals and front and rear seals in transmissions that use this sort of seal.

as for replacing them, generally it is cheap insurance, although i would not have an issue reusing a seal if it looked good, was still pliable
and was not distorted, torn or in someway damaged "and" was still mounted in the carrier, if however it has been removed
i would replace it rather than try and drive it back in place again.

bob g

[SHIPCHIEF]

I have noticed that these seals wear a groove in the steel shaft. Some seal replacement kits include a thin steel sleeve so the seal will have a smooth surface to ride on again.
The alternative: drive the new seal into the housing a little less or a little more so the seal lip rides on a smooth portion of the shaft, not the worn groove where the old seal rode. 

[veggie]

Your old seals could start leaking anytime in the near future.
Unless you enjoy pulling the flywheels, I suggest putting the new ones into service.
These seals are so inexpensive that it makes sense to install new ones IMHO.

veggie

[aqmxv]

I have noticed that these seals wear a groove in the steel shaft.

Nope.  The seal doesn't wear anything down - rubber is much softer than the shaft..  Dirt held by the seal wears the shaft down, which is why it was such a problem with rope seals on front-engined cars (front pulley was right behind the radiator being dirt-blasted, especially on dusty roads).  The easy way around this one is to get a double-lip seal.  The outer lip is not springloaded, but touches the shaft.  Its purpose is to keep dust away from the inner lip, which has the usual spring on it.

One thing I've considered doing is reversing the seals on a listeroid.  If everything is set up right, the crankcase should have negative pressure most of the time due to the action of the reed valve.  You would want the lips of the seal facing outward to keep air and dirt from entering at the seal lips...

[rl71459]

Many types of rubber have carbon in them and it indeed will wear a groove in a shaft. even on a hardened
toolsteel shaft that is clean on both sides of the lips. We see this frequently in Industrial machines that have grearcases that are divided by seals on shafts even when the seals are submerged in oil on both sides. Its a very troublesome issue that also contaminates the fluid or oil that the seal retains if it is a sensitive fluid. What we see is anything that rubs on a moving part will in time give off contaminants.

Rob