It would seem to me to consider the distinction between the load and bearing design considerations between a generator and a starter.
The generator runs all the time under relatively light rotational loading. The starter runs only when cranking the engine, as John states; but is more heavily loaded. If the engine is in decent shape and properly adjusted, only hot start vapor lock conditions require more than very brief engagement of the starter. It would seem that the original arrangement works great in a new engine. But in service, engines wear. Crankcase pressure tends to increase and that makes for leaks where none previously existed and previous leaks to leak more. The wear between the starter bushing and shaft increases the clearance through which oil can pass. What was once "enough" oil to lubricate the bushing becomes too much (and the annoying drip). John's description of what happens with the "new" seal was worth the giggle. But I would tend to believe if, after installation of the seal, the starter shaft/bushing were assembled with the right amount of a lubricant with the properties of STP, such would likely last the periods between disassembly to clean and inspect the brushes, armature and bearings. I am using the word "bearings" here to include the "bronze bushing". Then, to quote John: "Fast forward 50 years. The bushings wear to the point where the seal starts leaking, oil gets to the bushing to lubricate it, wear essentially stops, and everyone is happy." This process would not be like ketchup, where you go instantly from none to too much. I would think the "perfect balance" in which the seal allows just enough oil to stop bushing wear (not absolutely, but a definite rate reduction) would last a very long time; and when that first drop of oil does make it to the end of the shaft, one need only replace the seal to banish it for another fifty years. The bottom line, then, would be that the owner of a starter with the seal does not have an oil leak otherwise common. If and when such a leak is observed, the "fix" is relatively simple and cheap...and long lasting. This would suggest to me that the modification is a desirable one. But no one has suggested to how to do it "legally". Regards, WRB -- On Mar 9, 2010, at 11:47, John Cooper wrote: > On 3/8/2010 6:09 PM, Bob Swinney wrote: >> The starter shaft that moves in and out is leaking oil. Has anyone had >> this problem? > Probably everyone. > > A little history: > > Originally, no seal was used. the shaft runs in a bronze bushing and > only turns when the starter is activated. The flat surface of the drive > gear contacts the flat surface of the housing when the starter is idle. > a leather washer between the two effectively blocked the flow of oil. > when the starter is activated, a slight amount of oil gets behind the > washer. When the starter is deactivated, that oil makes its way into > the > bronze bushing and lubricates it. Any excess oil forms a drip on the > end > of the shaft and annoys the owner. > > No doubt, after fielding so many complaints from annoyed owners, > someone > at either Continental or Delco decided to mill the housing to accept a > seal. this eliminated the drip, at leas for as long as testing went > on, > and hence eliminated the complaints. However, now there is no oil > getting through to lubricate the bushing. > > Fast forward 50 years. The bushings wear to the point where the seal > starts leaking, oil gets to the bushing to lubricate it, wear > essentially stops, and everyone is happy. Except the owner, who is > annoyed... > > > > -- > John > Skyport East > www.skyportservices.net >
