Bearing type on Jabsco pump (engine mounted)

superheat6k

superheat6k

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I asked this on the Mobo forum but might get an informed answer on here.

My seawater pumps are engine driven (Cummins 6BT5.9M). As Thornycroft versions they do not use the OE supplied Sherwood pump. Instead the pump is a Jabsco 23434-1. I have removed one to replace a leaky seal, but the bearings are sloppy so I will change these also.

These are type 6203 sealed pre-greased. However the equivalent Johnson pump uses an open cage 6203, lubricated by splash feed from the adjacent timing gear case and drive gear spur.

Can anyone suggest why I should instead stick with Jabsco sealed bearings ? Annoyingly ASAP only offer the Johnson type, but do have the OE Jabsco seal. The oil lip seal right next to the outer most bearing was thoroughly wet with oil, so lubricant definitely finds its way into this area.

Also the shaft on the water side has a slight wear groove where the lip sits, I can opt for a tighter 15 mm lip rather than the original 16 mm, or a double lip, but I am concerned the outer lip might not get any lubrication at all.
 
Where possible I always fit double sealed ball bearings. I even try to get stainless steel ball bearings where water is close by as in the case of a water pump.

If you fit sealed ball bearings do not fit double lip seals, as you say the inner lip will have no lubrication(the one next to the bearing) where the outer/water side lip seal will be water lubricated.

I would change the shaft as any damage to the seal lip surface will ware the seal lip very quickly.
 
I used a shaft repair sleeve to repair the wear groove in a Jabsco, worked fine in commercial use with no problem.

Jim
 
Rogershaw said:
Where possible I always fit double sealed ball bearings. I even try to get stainless steel ball bearings where water is close by as in the case of a water pump.

If you fit sealed ball bearings do not fit double lip seals, as you say the inner lip will have no lubrication(the one next to the bearing) where the outer/water side lip seal will be water lubricated.

I would change the shaft as any damage to the seal lip surface will ware the seal lip very quickly.
Click to expand...
The shaft is an obsolete OE special, but the worn ring is very neat with no scratches, so I will simply polish this to remove any burrs or high spots.

There are two seals one next to the pump wear plate and impeller, the other next to the bearings with an exposed drip gap between with a slinger o ring.

Water getting to the bearings would mean water was getting into the engine sump. Although there was a steady trickle from the failed waterside seal nothing has passed the bearing side seal, and where this seal is oil lubricated there is barely a witness mark (980 engine hours over 25 years - from the undisturbed paint on the bolts and gasket edge this pump hasn't been off before).

I can buy the original sealed SKF bearing off EBay so will do this and get the seals from ASAP.
 
You have the bearing number - just order the equivalent bearings online from any reputable bearing supplier. You may be able to get generic seals too.

Bearings are a commodity item these days.
 
superheat6k said:
I asked this on the Mobo forum but might get an informed answer on here.

My seawater pumps are engine driven (Cummins 6BT5.9M). As Thornycroft versions they do not use the OE supplied Sherwood pump. Instead the pump is a Jabsco 23434-1. I have removed one to replace a leaky seal, but the bearings are sloppy so I will change these also.

These are type 6203 sealed pre-greased. However the equivalent Johnson pump uses an open cage 6203, lubricated by splash feed from the adjacent timing gear case and drive gear spur.

Can anyone suggest why I should instead stick with Jabsco sealed bearings ? Annoyingly ASAP only offer the Johnson type, but do have the OE Jabsco seal. The oil lip seal right next to the outer most bearing was thoroughly wet with oil, so lubricant definitely finds its way into this area.

Also the shaft on the water side has a slight wear groove where the lip sits, I can opt for a tighter 15 mm lip rather than the original 16 mm, or a double lip, but I am concerned the outer lip might not get any lubrication at all.
Click to expand...
I may be mistaken but, sealed bearings are not waterproof or oil proof like a lip seal is, the seal only keeps dirt etc out and grease in. So which ever you use should be fine. Your polishing if the shaft? I would do that, carefully! I would also use the original size lip seal, 1mm is a lot in terms of "tightness"
Stu
 
skipper_stu said:
I may be mistaken but, sealed bearings are not waterproof or oil proof like a lip seal is, the seal only keeps dirt etc out and grease in. So which ever you use should be fine. Your polishing if the shaft? I would do that, carefully! I would also use the original size lip seal, 1mm is a lot in terms of "tightness"
Stu
Click to expand...
I cleaned everything up today, and gave the shaft a very light polish with some very fine and worn wet & dry paper. Upon close inspection the polished ring is only a few thou at most, barely discernible with a fingernail, so not even 0.25 mm of the diameter, so I am going to stick with the 16mm ID seal, although this won't be the Jabsco original so the lip might sit in a different place anyway.

Our bearing supplier has offered me FAG bearing equivalent to the SKF Explorer, and I am more than happy to use FAG. I am ordering three full sets so I can do the port engine and have a set as on board spares. The whole lot are less than £40 including the two sealing O rings required. The metal mounting gasket (onto engine) will go again with a light smear of loctite 577.
 
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