Sealed vs open bearings. What's better?

Messages
5,988
Location
Houston, Texas
Thread starter
I found out today that even though I thought I made it clear that I wanted to buy the bearings for the driveshaft on my boat, the shop went ahead and used sealed bearings vs the open bearings it was supposed to have. Too late now I guess..... There was a zerk fitting on the bell housing, why would they do this? Am I making too big a deal out of this?
 

Kestas

Staff member
Messages
13,728
Location
The Motor City
I'm not familiar with the application. I'm assuming the bearing is mounted in a cavity the already excludes the environment. Every once in a while we see a sealed bearing specified in a closed cavity environment. This is to keep the break-in particles out of the bearing. The down side is that more heat is generated during operation.
 
Messages
5,988
Location
Houston, Texas
Thread starter
So is it too much to ask to get them to do the job again the right way? They pretty much have to remove the engine, remove the outdrive, and remove the bell housing which in cases the two bearings. Why do I have to pay for work done incorrectly? How come I always get the shaft whenever i pay people to do things?
 
Last edited:
Messages
1,467
Location
Maryland USA
Originally Posted by motor_oil_madman
So is it too much to ask to get them to do the job again the right way? They pretty much have to remove the engine, remove the outdrive, and remove the bell housing which in cases the two bearings. Why do I have to pay for work done incorrectly? How come I always get the shaft whenever i pay people to do things?
What bearings are you talking about ? Initially I thought you meant the gimbal bearing that is in the gimbal housing. But there is only one bearing there- the old style was open and able to be greased, while the new style is sealed. Is this a Merc Alpha One or Bravo drive ? Having torn apart numerous Merc stern drives I might be able to give you a non-biased answer.
 
Messages
2,678
Location
Chicagoland
I'd ask for a warranty on it since they did the exact opposite of what you asked, or make it right and do what you had asked for in the first place.
 
Messages
5,988
Location
Houston, Texas
Thread starter
Originally Posted by rubberchicken
Originally Posted by motor_oil_madman
So is it too much to ask to get them to do the job again the right way? They pretty much have to remove the engine, remove the outdrive, and remove the bell housing which in cases the two bearings. Why do I have to pay for work done incorrectly? How come I always get the shaft whenever i pay people to do things?
What bearings are you talking about ? Initially I thought you meant the gimbal bearing that is in the gimbal housing. But there is only one bearing there- the old style was open and able to be greased, while the new style is sealed. Is this a Merc Alpha One or Bravo drive ? Having torn apart numerous Merc stern drives I might be able to give you a non-biased answer.
Mine is an older Volvo penta drive and has two open bearings called primary driveshaft bearings inside the flywheel housing. So instead of global bearing they're called pds bearings.
 
Last edited:
Messages
5,988
Location
Houston, Texas
Thread starter
Originally Posted by Kestas
I'm not familiar with the application. I'm assuming the bearing is mounted in a cavity the already excludes the environment. Every once in a while we see a sealed bearing specified in a closed cavity environment. This is to keep the break-in particles out of the bearing. The down side is that more heat is generated during operation.
Yes it's supposed to be in a grease cavity. Although now since they put sealed bearings in, maybe that cavity no longer needs to be filled with grease.
 
Messages
320
Location
Reno, Nevada
I'd talk to the shop, maybe they had a good reason to install sealed bearings based on their experience. One of the issues with bearings greased through Zerk fittings is dirt contamination, incompatible grease and over greasing. Sealed bearings will probably run a long long time. I would be more concerned that they used quality bearings from SKF, NTN, etc.
 
Messages
74
Location
warm and sunny ND
I service medium to large Air Handler Units. College campus units. 40 or more. Ive been to the bearing classes. Ive been to the ultrasound testing classes. Improper grease, contaminants introduced while greasing and over greasing are the main causes of bearing failure. Since I took over the greasing route the AHU bearings are running cooler and quieter. Main reason is I don't give the bearings a shot or 6 of grease every month. Some of the ones that ran hot are room temp now because I have not given them ANY grease for 2 months. Trust me they likely did you a favor with sealed bearings. That way the mechanic that thinks you need to pump in grease until it comes out the side cannot screw up your bearings.
 
Messages
318
Location
VA
I also have an older volvo/penta combo with the SX outdrive. My gimbal bearing is sort of a hybrid. It looks like it is sealed but with a metal seal instead of rubber but it has a hole in to seating surface which lines up with a hole in the housing which leads to a zerk fitting on the outside of the gimbal housing. Some grease will come out of the bearing around a very small gap in the seal...so I guess maybe you could call it a shrouded bearing.
 
Messages
74
Location
warm and sunny ND
Just an FYI every class I have taken with the "experts" have always claimed that if you see grease coming out the side of the bearing you have over greased it. Listening with the ultrasound unit as you greasing actually confirms over greasing. The smooth bearing sound becomes noisy just before the grease comes out the side and the bearing temp goes up.
 
Last edited:
Messages
5,988
Location
Houston, Texas
Thread starter
Supposedly the volvo penta kit contains SKF bearings, so that's good atleast. He's also saying that even though the bearing is sealed, you can still grease it at the zerk fitting, the grease will penetrate through the seal, Sounds like bs to me, but whatever.
 
Messages
5,988
Location
Houston, Texas
Thread starter
Originally Posted by Kestas
I'm not familiar with the application. I'm assuming the bearing is mounted in a cavity the already excludes the environment. Every once in a while we see a sealed bearing specified in a closed cavity environment. This is to keep the break-in particles out of the bearing. The down side is that more heat is generated during operation.
Well it's just a 12" long shaft inside the bell housing attached to the flywheel coupler and the u joints on the outdrive. I don't know think the flywheel gets hot on an engine so I'm hoping heat won't be an issue. Yes they are incased in a grease cavity. I believe the shaft itself still needs grease? Basically a 1.5" diameter 12" long shaft with a bearing on each end.
 
Last edited:
Messages
5,988
Location
Houston, Texas
Thread starter
Originally Posted by Kestas
I thought it may have been in an oil application. In this case shedding heat is not an issue for sealed bearings.
The mechanic also said that the grease will still squeeze into the sides of the bearing even though they're technically sealed. I'm not sure I believe that though. I know a sealed bearing basically just has a rubber cover on it, so I suppose more grease can go in.
 
Top