Navigator oil problem

Hi Ulrich, I can't see how mixing the breather and mist pipes up could cause the wet sumping although it could cause excessive lubrication of the chain - I've made that mistake in the past and it had that effect.   All my Lightweights have wet sumped to a greater or lesser extent but no where near as much as that and not that quickly.   Did you recondition the oil pump or replace it with a new one when you rebuilt the engine?   Excessive oil pump wear will allow oil to drain back down into the sump like that.   Checking or replacing the oil pump is a reasonably straight forward job but does require taking the timing side cover off which inevitably means retiming the engine I'm afraid!   If I am doing that job I always remove, check and clean the oil pressure relief valve and it's gauze filter and replace the crank shaft oil seal and the one behind the points (making sure they are the right way round!).   The other cause of leaking round the drive sprocket is the oil seals behind the gearbox sprocket and clutch - a check of the gearbox and primary chain case oil levels will give you a clue to whether that is happening.   Another less obvious one is a leaking crankshaft oil seal on the primary side - that allows engine oil and piston blow by to leak into the primary chain case pressurising it and forcing oil past the oil seal behind the clutch with the effect you have seen.   When I first got my Navigator I had oil leaking from round the gearbox sprocket and I had to replace all three of those seals to cure it.   Sorry that all seems negative and extra work but since I replaced all those seals my engine has stayed remarkably oil tight - it can be done!   I hope that helps, good luck and keep at it, the Navigator is a great little bike once you have got it settled down!   Nick      

Another thing to look at is the sump plate & gaskets at the bottom of the engine, and that the oil return hole is not closed or blocked by gasket cement/silicon. Its a common mistake that is easy to make. Oil comes down to the engine - but cannot get back - except via the breather.

The oil, after use, drops to the bottom of the engine onto the sump plate via a strainer, then towards the timing side, where a pipe sucks it up to the pump - which pumps it back to the tank & rocker box.

There may be an article about this very subject in a Roadholder shortly....

The picture below shows such an instance of a blockage.

I see you found the problem! It was the same as I suggested .... but the blockage had moved!

You still need to check that all is OK in the area of the sump plate.

Well done Ulrich, having the time to fettle the Navigator is a positive of the lock down!   It always surprises me how much you need to torque down head nuts after the initial running in period which proves why it is so important and worth all the work to expose them.   The healthy oil return sounds very promising and something I obsessively check, the dreaded silicone sealant blockage is always worth having at the back of your mind.  Lets hope that has cured your oil leak problem and you can now enjoy a successful running in period.  Keep us posted!    Nick  

Beware of too much pressure when torqueing down the head nuts.

The book states 15 foot/pounds (15ft/lb). DO NOT EXCEED THIS!

Google tells me the Metric Equivalent is 20.34 Nm - (I hope that is correct).

Remember to do all 6 on each head in the proper sequence, to avoid distorting the heads.

Wise words Andy, I so wish I had owned a torque wrench back in the 70s and 80s, it would have saved me so much wasted effort, hard won cash and heart break!  

A good friend of mine taught me to use wellseal applied with a paint brush on one half of the case - does not matter which, apply gasket then wet exposed surface with grease or oil, then wellseal the mating face with paint brush. Oil helps the gasket come away when disassembling. The advantage with wellseal is it will not block oilways, as seen from above pictures it takes a very small amount of goo to cause a real pain. Seems a bit old school but very satisfying and seems to me it cant go wrong. I have also come across an article the suggests use of silk thread and wellseal. I used that for my crankcases - dry so far. Though I have leaks else where ;-)

Regardless of what it tells you on the tube silicon sealant has no place in the rebuilding of engines. Invariably people use vastly to much sealant, with silicon this is a recipe for disaster and can lead to a blown up motor ,which I've seen . Silicon is for bathrooms.                 Far better is Wellseal, like a thin varnish, petrol proof and non hardening, applied sparingly with a small artists brush it works, I've  never used anything else.