Vintage car dynamo problem
Discussion
My car runs directly off the 1925 Meadows engine and works OK, except :
a very small amount of engine oil is passing along the interior of the dynamo and wetting the brushes. Even though the car is up for sale I would like to resolve this problem which has plaqued me for three years. The dynamo is original to the car (1925) so my feeling is it must be a seal on a bearing worn as I can see no other means of an oil tight connection onto the engine. Or am I missing something? Thanks
a very small amount of engine oil is passing along the interior of the dynamo and wetting the brushes. Even though the car is up for sale I would like to resolve this problem which has plaqued me for three years. The dynamo is original to the car (1925) so my feeling is it must be a seal on a bearing worn as I can see no other means of an oil tight connection onto the engine. Or am I missing something? Thanks
Some units used a simple felt seal that stopped oil from working it's way into the brushes, and if this has hardened due to age and shrunk then this could be the cause, or if it has simply dissintigrated due to age also. Some units had a simple swirl machined into the main shaft that pushed the oil back from whence it came and if these have been used from another engine could be running the wrong rotation that promotes oil into the unit.
Thanks for the informative reply Peter, think I shall take the dynamo off again for another inspection. At least this time I have an better idea of what to look for. When I purchased the car I cleaned the brushes of the oil and the dynamo worked fine for a period of time. That period of time shortend as the months wore on, now the dynamo seems hardly to work at all. Clearly whatever is causing this problem has degraded further and further, therefore your reply makes a lot of sense to me.
Edited by crankedup on Saturday 5th December 11:46
It ought to be obvious what's wrong from a stripdown and proper examination. If the oil control is via a sealed bearing it might be possible to find a better modern replacement with built in neoprene or teflon seal rather than felt, leather, hemp rope or whatever they used in 1925. Bearings tend to be made to standard sizes even going back that long. If not then a simple machining mod to fit a modern bearing might be possible.
If it's some sort of packing round the shaft then that just needs redoing properly. Plenty of older engines had that sort of arrangement on the crankshaft. Usually a rope seal you have to cut to an exact length packed with grease. I remember having to do one on a rebuild of a Daimler Dart 2.5l V8 and crapping myself that I'd get it wrong and have to redo it. It was completely oil tight though I was later told thank god.
If there's a reverse scroll machined into the shaft to wind oil back down the way it came then that might be blocked with deposit build ups or there might be wear on it or the casing. Again I've seen those on cranks on older engines.
If it's some sort of packing round the shaft then that just needs redoing properly. Plenty of older engines had that sort of arrangement on the crankshaft. Usually a rope seal you have to cut to an exact length packed with grease. I remember having to do one on a rebuild of a Daimler Dart 2.5l V8 and crapping myself that I'd get it wrong and have to redo it. It was completely oil tight though I was later told thank god.
If there's a reverse scroll machined into the shaft to wind oil back down the way it came then that might be blocked with deposit build ups or there might be wear on it or the casing. Again I've seen those on cranks on older engines.
Thank you, interesting info' again. I have found what I think is the major source of the problem. The brushes section is sealed off from the armiture section by an fairly hefty alloy plate, Having moved a few wires whilst having an general scrummage about I noticed a flippin' hole in this plate! It certainly looks like it was machined and has an electrical wire leading into the armiture section via this hole. I can only surmise that this hole should have an 'bung' to seal it. I shall try some silicone and see if this stops the oil bypass?
Has the hole in the alloy plate worn or become oval due to wear? If so then this will not stop it completely.
What you could do is place an 'O' ring on the shaft which butts up against the alloy plate this would help, or wrapp some hemp around the shaft which could act as a rope seal as spoken by Pumaracing.
What you could do is place an 'O' ring on the shaft which butts up against the alloy plate this would help, or wrapp some hemp around the shaft which could act as a rope seal as spoken by Pumaracing.
If only I could do pictures, but I'm a total nobber at things like that. The little hole I mention is perfectly formed and I'm sure it was engineered to be as is. A couple of the electrical wires thread thru it, my guess is the grommet is missing. As I have been advised its almost certain that the main problem is down to the armiture shaft seal or/and the spiral thread thingii. I have decided to take it along to an expert nearby in Burnham on Crouch.
If you would like to post an idiots guide to pic' posting I shall have a go.
If you would like to post an idiots guide to pic' posting I shall have a go.
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