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sealed VS open ball bearing inside an engine?

Garwood

Diamond
Joined
Oct 10, 2009
Location
Oregon
Has anyone seen an example of a sealed (-2RS) ball bearing used in a gas/diesel/motorcycle/boat engine application where it's exposed to engine oil?

I'm working on a re-design of a 1980's engine product that used an open 6004 C3 bearing with minimal splash lube. I'm planning to use the same size bearing, but sealed. My transmission experience says sealed ball bearings last much longer in oil sumps. But never seen any used in engine oil.
 
A sealed bearing in an oil sump would be almost an ideal arrangement by my thinking, it's perfect lubrication and the oil bath cooling without any cross contamination.
 
Hmmm......

I think it's not a good idea. Why? I'm not sure. Partly because if it were a good idea, the people who have spent millions on R&D (automakers, motorcycle makers) would already be doing it.

I also think a sealed bearing has lower performance than the comparable open bearing. That is what I recall based on looking at ratings charts on load and RPM. They don't cool as well.

Another argument against it is the failure mode where the engine oil either gets past the bearing seal or attacks it enough that the oil gets in and washes out or dilutes the grease, but is not actually flowing enough to be cooled and refreshed, etc.

If it was me...I'd look at getting better oiling to the open bearing, if possible.

All that said, you don't indicate what type of service this engine will see. If it's an over the road truck that need to last 500K miles, that's one thing. If it's a kiddie train puller that runs twice a month, that's another. Also matters if you own it or if it's a customer's.
 
MMMM? ...I'm thinking that with most engines it's such a maelstrom of oil and mist that such an amount of circulated and filtered oil will be far better than a dab of grease inside a sealed bearing.

Then there's heat, deep inside engines get hot, (anyone ever drained really hot oil and had it run down their arm??? ) ........... maybe too hot for a decent life out of the rubber seals, ........... and if they do break up - what happens to the bits.

Shut up Sami n go to bed.
 
Hmmm......

I think it's not a good idea. Why? I'm not sure. Partly because if it were a good idea, the people who have spent millions on R&D (automakers, motorcycle makers) would already be doing it.

I also think a sealed bearing has lower performance than the comparable open bearing. That is what I recall based on looking at ratings charts on load and RPM. They don't cool as well.

Another argument against it is the failure mode where the engine oil either gets past the bearing seal or attacks it enough that the oil gets in and washes out or dilutes the grease, but is not actually flowing enough to be cooled and refreshed, etc.

If it was me...I'd look at getting better oiling to the open bearing, if possible.

All that said, you don't indicate what type of service this engine will see. If it's an over the road truck that need to last 500K miles, that's one thing. If it's a kiddie train puller that runs twice a month, that's another. Also matters if you own it or if it's a customer's.

Sealed bearings cool the same as open, but the seals keep the contaminates out. Aisin switched to using sealed bearings inside transmissions and transfercases around 1995. There is a huge difference in service life for the same transmission models made with open bearings vs sealed.

I still see sealed used where oil flows through a ball bearing.

As for my application, think of the bearings in the power take off ports on the timing housing of a semi engine. They spin at crankshaft speed. Lube is a healthy mist/splash.
 
I know open bearings will work for what I need. The bearings in this application never were a problem. Load is very light.

Thing I'm concerned more about is that if I make this product with an open ball bearing it's gonna be shipped around the world, get handled in grimy shops, dropped in the gravel, bolted onto engines that never get their oil changed- You get the idea. If there isn't a downside then I'd like to use sealed bearings for my piece of mind knowing shit can't get in the bearings.

I just don't see ball bearings used much in any engines I work on. The older ones I'm familiar with do use some (like my PTO example above). If I saw a modern engine that had sealed ball bearings in use somewhere in contact with engine oil I'd call that a good indicator I won't have problems.
 
The old Norton motorbike gearbox used a pair of sheetmetal shields as an oil seal ....and its common to replace the ball bearing with a 2RS one to keep some of the oil in the gearbox.....ball bearing seals are quite flimsy ,and the slightest knock will pop them out of the bearing......in fact ,if you dont want a 2RS bearing,you simply remove the seals .
 
Has anyone seen an example of a sealed (-2RS) ball bearing used in a gas/diesel/motorcycle/boat engine application where it's exposed to engine oil?

I'm working on a re-design of a 1980's engine product that used an open 6004 C3 bearing with minimal splash lube. I'm planning to use the same size bearing, but sealed. My transmission experience says sealed ball bearings last much longer in oil sumps. But never seen any used in engine oil.
Crank stuffing is a common two stroke performance method.
I ran Double sealed Main bearings in a Kawasaki 238 Green Streak scrambler. on a short track engine build back in the 70s. The engine ran strong and lasted many years racing every week end. That was a two stroke with 40:1 Bardahl mix gas and oil.

It might be noted that roller bearing cranks go to great lengths to LIMIT oil to the bearings. (think H-D) too much oil is no good.
 
Crank stuffing is a common two stroke performance method.
I ran Double sealed Main bearings in a Kawasaki 238 Green Streak scrambler. on a short track engine build back in the 70s. The engine ran strong and lasted many years racing every week end. That was a two stroke with 40:1 Bardahl mix gas and oil.

It might be noted that roller bearing cranks go to great lengths to LIMIT oil to the bearings. (think H-D) too much oil is no good.

I didn't even think about 2 strokes. Thanks for bringing that up.
 
I did that on an Ingersoll Rand two-stage air compressor. The open bearing on the non-drive end of the crankshaft went bad. I replaced it with a sealed bearing that outlasted the compressor.

I'm surprised it didn't have a Timken tapered roller bearing with a filtered oil supply (actually, I'm not).
 
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the main argument against sealed ball bearings is they have a lower max rotational speed due to the contact seals vs. shields/ open. Another consideration is a slight amount of drag, though I can't imagine that would be an issue in this application. I don't think either are likely to be an issue for bearings run at crank speed in a diesel engine
 
IMHO This is a very good Q, ..............but I keep coming back to the ''if it was better they'd be doing it already'' .............and we know the price difference between sealed and or shielded bearings and open is (normally???) minimal.
 
Back in the day shielded bearings were, in practice, de-rated for speed and load compared to unshielded ones if long service life was expected. Properly engineered systems used real seals and re-greasing at suitable intervals was considered normal. Higher temperatures and speeds, such as in an engine, were the province of open bearings with copious clean(ish) oil or oil mist lubrication.

These days cheap sealed bearings do fine in things like inexpensive oil-free compressors spinning at around 3,000 rpm under high, for the size of the bearing, cyclic loads.

Pretty much all down to lubricant development. 1950 vintage grease would never survive the speed, load and temperatures involved inside an engine of any sophistication. OK may be a Lister single but thats only half a step up from hit'n miss!

Modern grease formulations used in good bearings should be well up to the task but it would be prudent to verify temperature soak and permitted rpm specifications for the ones you plan to use. I've seen grease run out of an overheated sealed bearing, albeit grievously abused.

The other point is seal quality. The seals aren't that effective compared to proper shaft seals being intended to merely keep crap out and grease in. The seal itself is largely made by the thin ring of "excess" grease that works out of the bearing proper once it goes into service. I suspect that oil mist will make its way into the bearing so how well the grease will hold up when contaminated is an open question. That said a decent bearing, properly specified, ought to hold up way better than an old money, inexpensive, open bearing.

Clive
 
Clive - I'm not all that happy about the Lister ''pop'' ......there's a damn sight more to Lister / Petters than many give credit for, .especially the diesels.
 
I would try it because I'll try almost anything but the one thing I'd be concerned about is, if the seal breaks down from heat or whatever, then disintegrates inside the engine .... I guess the oil filter should take care of that but still, something to think about ?
 
MMMM? ...I'm thinking that with most engines it's such a maelstrom of oil and mist that such an amount of circulated and filtered oil will be far better than a dab of grease inside a sealed bearing.

Then there's heat, deep inside engines get hot, (anyone ever drained really hot oil and had it run down their arm??? ) ........... maybe too hot for a decent life out of the rubber seals, ........... and if they do break up - what happens to the bits.

Shut up Sami n go to bed.
well .......did you go to bed???
 
Do a Google search for "Porsche IMS bearing failure". They thought a sealed internal bearing was a good idea. NOT! Many failures happened long out of warranty. Mostly to Garage Queens. Friend had scooped up a really nice garage queen Cayman S and started doing track days. He got a few track days before his car became a rolling chassis. When those bearings failed the engine was junk. We have a local PCA member who was fairly high up at Timken Bearings and he and others came up with some sort of fix. But the cars that were always driven hard had very few issues.
 








 
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