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Oil pump question

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Oil pump question

Posted by terry_grimwood at May 14. 2018

Not sure if the oil pump on my Navigator is up to scratch. Actually I know it isn't because the bike wet sumps after only a few days; what I don't know is how serious it is. The return to the tank could best be described as a steady stream - more than a trickle but not a gushing flow - and the feed to the rockers also shows a steady flow but with intermittent air bubbles, not a steady stream. Should I be worried?

Terry

Re: Oil pump question

Posted by andy_sochanik at May 16. 2018

No - quite the opposite. Your pump is working fine. A steady stream is what to expect while the oil is in the sump. The return is twice as fast as the feed to the engine, so eventually, when all the oil is returned to the tank, the stream becomes intermittent.

Sadly, all classic Nortons drop their oil into the sump (except Mk III Commandos). The only thing that varies is the speed at which it happens.

There are two courses of action - live with it, or try to mitigate the effect.

You could try to live with it - it depends how often you use the bike. In the old days, when we used the bike almost every day for work or play, it was never an issue. Now, of course, it can stand for a week or more - and the oil dribbles down to the sump. And, maybe for 4 months (or more) over winter, we don't use it at all. The NOC sells a sump plate with a Drain Plug - you could use that to drain the oil and return it to the tank manually. Or, if you know you are not going to use the bike for a while (eg, winter is coming) you could drain the oil tank after a run - but please stick a note over the speedo that you did so! Another trick to slow the rate at which the oil does drain down to the sump is to make sure the pistons are at TDC (Top Dead Centre). In this way, there is least 'head' of oil forcing its way down.

Or you can try to mitigate the effect by reconditioning the oil pump. This could be costly, and all it will do is slow down the rate at which the oil passes through the gears. The usual reason that the pump lets oil pass quicker than normal is that the end plate has got smeared with dirty oil. Once you have the end plate flattened again & the gears inspected, fit an aftermarket oil filter kit - again the NOC sells one with a bracket to mount it under the swing arm. Although it cleans the oil after its been through the oil pump, its better than letting that stuff circulate round and round. Again, in the old days, any stuff drifting round in the oil would have been trapped in the centre of the crankshaft by centrifugal force - nowadays, detergent oils keep this stuff circulating - to the detriment of the pump & bearings.

Another way round this problem, is to fit a non-return valve in the oil feed to the engine. This is how its done by the manufacturer on Velocettes, for example. But most people think that this is an unsatisfactory solution, as it introduces a ball bearing into the oil line ABOVE the pump. All that you rely on to lift that ball bearing off its seat is atmospheric pressure - 14lbs/sq ft. So you will have now introduced a possible source of failure at some point in the future.

The only solution to Wet Sumping is to fit a tap to the oil feed to the engine. It must be a full-flow type (where you can see through it when open) so that there is no restriction to oil flow when open. But again, you have to invent a way to stop the engine firing up, if the tap is OFF. A micro switch wired into the ignition, which is activated by the pump lever, is one way to do it. Sadly, on a Jubilee, Navigator or Electra, to gain access to such an oil tap will mean leaving off (or worse - cutting a hole in) a panel.

In my own case, I have learned to live with it. I start the engine & let it tick over until most (or all) the oil is back 'upstairs'. You can tell when this has happened when the return flow (conveniently situated under the tank cap) becomes intermittent. There is a down side to this, in that there is (initially at least) much greater pressure under the pistons. As the breather is untimed on these models, most of that pressure will be vented to the oil tank (with oil as well) - but if you increase that pressure (by revving the engine, for example) then it's possible to blow off the crankcase oil seal into the primary chaincase.

Hope this helps...

Re: Oil pump question

Posted by terry_grimwood at May 16. 2018

Previously andy_sochanik wrote:

No - quite the opposite. Your pump is working fine. A steady stream is what to expect while the oil is in the sump. The return is twice as fast as the feed to the engine, so eventually, when all the oil is returned to the tank, the stream becomes intermittent.

Sadly, all classic Nortons drop their oil into the sump (except Mk III Commandos). The only thing that varies is the speed at which it happens.

There are two courses of action - live with it, or try to mitigate the effect.

You could try to live with it - it depends how often you use the bike. In the old days, when we used the bike almost every day for work or play, it was never an issue. Now, of course, it can stand for a week or more - and the oil dribbles down to the sump. And, maybe for 4 months (or more) over winter, we don't use it at all. The NOC sells a sump plate with a Drain Plug - you could use that to drain the oil and return it to the tank manually. Or, if you know you are not going to use the bike for a while (eg, winter is coming) you could drain the oil tank after a run - but please stick a note over the speedo that you did so! Another trick to slow the rate at which the oil does drain down to the sump is to make sure the pistons are at TDC (Top Dead Centre). In this way, there is least 'head' of oil forcing its way down.

Or you can try to mitigate the effect by reconditioning the oil pump. This could be costly, and all it will do is slow down the rate at which the oil passes through the gears. The usual reason that the pump lets oil pass quicker than normal is that the end plate has got smeared with dirty oil. Once you have the end plate flattened again & the gears inspected, fit an aftermarket oil filter kit - again the NOC sells one with a bracket to mount it under the swing arm. Although it cleans the oil after its been through the oil pump, its better than letting that stuff circulate round and round. Again, in the old days, any stuff drifting round in the oil would have been trapped in the centre of the crankshaft by centrifugal force - nowadays, detergent oils keep this stuff circulating - to the detriment of the pump & bearings.

Another way round this problem, is to fit a non-return valve in the oil feed to the engine. This is how its done by the manufacturer on Velocettes, for example. But most people think that this is an unsatisfactory solution, as it introduces a ball bearing into the oil line ABOVE the pump. All that you rely on to lift that ball bearing off its seat is atmospheric pressure - 14lbs/sq ft. So you will have now introduced a possible source of failure at some point in the future.

The only solution to Wet Sumping is to fit a tap to the oil feed to the engine. It must be a full-flow type (where you can see through it when open) so that there is no restriction to oil flow when open. But again, you have to invent a way to stop the engine firing up, if the tap is OFF. A micro switch wired into the ignition, which is activated by the pump lever, is one way to do it. Sadly, on a Jubilee, Navigator or Electra, to gain access to such an oil tap will mean leaving off (or worse - cutting a hole in) a panel.

In my own case, I have learned to live with it. I start the engine & let it tick over until most (or all) the oil is back 'upstairs'. You can tell when this has happened when the return flow (conveniently situated under the tank cap) becomes intermittent. There is a down side to this, in that there is (initially at least) much greater pressure under the pistons. As the breather is untimed on these models, most of that pressure will be vented to the oil tank (with oil as well) - but if you increase that pressure (by revving the engine, for example) then it's possible to blow off the crankcase oil seal into the primary chaincase.

Hope this helps...

Re: Oil pump question

Posted by terry_grimwood at May 16. 2018

Previously Terry Grimwood wrote:

Previously andy_sochanik wrote:

No - quite the opposite. Your pump is working fine. A steady stream is what to expect while the oil is in the sump. The return is twice as fast as the feed to the engine, so eventually, when all the oil is returned to the tank, the stream becomes intermittent.

Sadly, all classic Nortons drop their oil into the sump (except Mk III Commandos). The only thing that varies is the speed at which it happens.

There are two courses of action - live with it, or try to mitigate the effect.

You could try to live with it - it depends how often you use the bike. In the old days, when we used the bike almost every day for work or play, it was never an issue. Now, of course, it can stand for a week or more - and the oil dribbles down to the sump. And, maybe for 4 months (or more) over winter, we don't use it at all. The NOC sells a sump plate with a Drain Plug - you could use that to drain the oil and return it to the tank manually. Or, if you know you are not going to use the bike for a while (eg, winter is coming) you could drain the oil tank after a run - but please stick a note over the speedo that you did so! Another trick to slow the rate at which the oil does drain down to the sump is to make sure the pistons are at TDC (Top Dead Centre). In this way, there is least 'head' of oil forcing its way down.

Or you can try to mitigate the effect by reconditioning the oil pump. This could be costly, and all it will do is slow down the rate at which the oil passes through the gears. The usual reason that the pump lets oil pass quicker than normal is that the end plate has got smeared with dirty oil. Once you have the end plate flattened again & the gears inspected, fit an aftermarket oil filter kit - again the NOC sells one with a bracket to mount it under the swing arm. Although it cleans the oil after its been through the oil pump, its better than letting that stuff circulate round and round. Again, in the old days, any stuff drifting round in the oil would have been trapped in the centre of the crankshaft by centrifugal force - nowadays, detergent oils keep this stuff circulating - to the detriment of the pump & bearings.

Another way round this problem, is to fit a non-return valve in the oil feed to the engine. This is how its done by the manufacturer on Velocettes, for example. But most people think that this is an unsatisfactory solution, as it introduces a ball bearing into the oil line ABOVE the pump. All that you rely on to lift that ball bearing off its seat is atmospheric pressure - 14lbs/sq ft. So you will have now introduced a possible source of failure at some point in the future.

The only solution to Wet Sumping is to fit a tap to the oil feed to the engine. It must be a full-flow type (where you can see through it when open) so that there is no restriction to oil flow when open. But again, you have to invent a way to stop the engine firing up, if the tap is OFF. A micro switch wired into the ignition, which is activated by the pump lever, is one way to do it. Sadly, on a Jubilee, Navigator or Electra, to gain access to such an oil tap will mean leaving off (or worse - cutting a hole in) a panel.

In my own case, I have learned to live with it. I start the engine & let it tick over until most (or all) the oil is back 'upstairs'. You can tell when this has happened when the return flow (conveniently situated under the tank cap) becomes intermittent. There is a down side to this, in that there is (initially at least) much greater pressure under the pistons. As the breather is untimed on these models, most of that pressure will be vented to the oil tank (with oil as well) - but if you increase that pressure (by revving the engine, for example) then it's possible to blow off the crankcase oil seal into the primary chaincase.

Hope this helps...

Many thanks Andy for such a comprehensive - and generally reassuring - reply. I have already fitted an oil-filter kit but without doing anything to the oil pump. Perhaps I should. I have also fitted the replacement sump plate with the plug in it which at least makes draining the sumped oil a lot simpler. I did get hold of an in-line tap that I planned to install it in such a way that I would not forget to turn it back on but, as you so rightly point out, there's nowhere to fit it while retaining the trim panel. Hey ho, it seems I shall just have to live with it. At least I don't have to worry about the rather weedy oil flow now.

Thanks again

Terry

Re: Oil pump question

Posted by ulrich_hoffmann at May 16. 2018

A friend of mine also had an inline-tap-of-death mounted to his Commando.

The engine ran 50 kilometres without oil....then he needed new camshaft and tappets..

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