Sorta on sorta OT-Rubber seals vs hard steel wear

[1just4don]

I guess I am the dullest knife in the drawer but for the life of me I can never figure this out,,,the why of it happening.

The OFF topic part is it was on a 4 cylinder Deutz motor this time

The ON topic is we ALL have seals and rotating iron.

My question is,,,how in the world does a rubber based oil seal wear a groove into a hardened steel crank(or any other rotating shaft)??

This 4 cly. is a slow rev motor too alot like our flat heads( 2000 rpms maybe 2200 tops),,,not a terrible amount of duty as a stationary irrigation use. Took rear main seal housing off and sure as the world,,,the 'seal' looked good yet,,,but the hardened steel crank it runs on(probably most of 6" diameter) had grovee deep enough to have one of those 'expensive' speedy sleeves which was almost twice as high as the seal,,which was twice too high to start with.

Besides being behind a "heavy" dang old flywheel that weights too much to hold up and start those magical fine threaded bolts,,,all 10 of them!! Wish somebody would have told me I needed a power plate puller.

When the motor is 1/2 mile from the shed thru a couple sets of gates and you make the tenth run for MORE tools and homemade pullers,,it gets to be a long hot day!!

I guess its all done now,,,but havent started it yet to see if it leaks worse than when I started!! But it just seems to reason here that hardened steel cranks should wear 1000 times longer than a rubber based oil seal,,,what say YOU??? Why does this happen?? Have it on other equipment too,so always wondered that?? --just don--

[Allan Faust]

I dont know exactly how the rubber does it, but if you think about it, given the right conditions etc.... water will cut like, and even better than, a knife.....

Allan

[Norm's Coupe]

Maybe the rubber seal is too soft for what it has to support. So, each time the shaft rolls around it is pushing the seal back and hitting the outer metal. Then you get the groove cut in your shaft.

[Merle Coggins]

I don't understand exactly why it happens, but it does happen a lot. I see it often. That's why there are "Speedy Sleeves" available.

Merle

[1just4don]

the seal on this motor is in a big pewter holder and its bolted into place with about 8-10 bolts from the back and three up thru the pan. It doesnt support anything. It cant run out that much cause it IS the back end of the crank it runs on. It is ALL rubber for like a half inch around it,,,and then that tin metal. Old one looked really like new when I took it out,,,so wasnt tore up. And that HAD more rubber on it than the new one.. It HAS to be the action of the rubber rubbing on that HARD steel crank. And this is just the back of the oil pan so gets a splash I spose from the crank splashing in oil pan. this particular motor is 'known' to do this!! And I was told from the get go it was why it was puking almost a gallon of oil in 24-48 hours. It was more or a "RUN" out of it rather than a drip!!!

Somebody said this is from dirt and grit getting caught under the lip of the seal..But is SUCH a place, not 'alot' of dirt can get in there,,,unlike say a harvesting machine!! I am still perplexed!!! or --just don--

[Young Ed]

I think its just from so many revolutions wearing a hole. Our cars and trucks do the same thing. The crank will do it at the front cover seal and the rear main. Also the pinion seal will do it too in the rear end.

[builtfercomfort]

I think also that tiny bits of metal get embedded in the rubber and act as an abrasive. Anything will cut anything (just about) with enough time and wear. Can you get the critical part of the crank nitrated or case-hardened?

[1just4don]

I used a speedy sleeve,,,never used one of those before. So I ask dumb question,,,will this sleeve last longer than original surface on the crank where it ran before?? Is it a 'harder' surface??

I did it this way so I didnt need to remove crank. AN overhaul on these is a major proposition. Costs as much as buying a new one!! Just want to throw a cork in the oil flow. ALL the head bolts twist off on these motors and you have to have a 'special' guy drill and make those good again and HIS price is as high as the overhaul labor,,,plus parts, it triples the cost real quick!!!

NUMBER #2 reason I did this is it ISNT my motor!!! Just my place to make the best of a bad situation!! Just wondering how something that soft can cut something that hard???

Think that surface 'should' have been hardsurfaced from the factory. BUT they may not have known this was a common problem when this was built,,,one of the first models !!

[Plymouthy Adams]

I have used the speedy sleeve a lot when I worked for Ford..seems they were really soft I guess and as such ned them..of course these were on the harmonic balance but same principle...they are sufficient to do the job and easily renewed if needed.