Baffled, confused and covered in oil!!!!!!

[bikerboy]

I was so happy thinking I had cured it and the damned thing still throws all its oil out once it gets hot

5 years off and on I have messing about with this bike (I do have other projects)

I ran it in the workshop and it got damned hot (no air flow of course) When it got hot it started pumping oil out of the breather AGAIN

Let it cool and stripped the top end off it. OVER a pint of oil in the sump????

So basically when it gets hot it is not scavenging properly.

I am gutted it was 100% oil tight and ran fantastically barring the oil problem.

I checked for wet sumping and it does not wet sump at all. A full oil tank the sump off and there is literally nothing after 3 days coming out of the sump.

I am now going to strip it completely either its the scavenge pipe cracked and the crack opening up when it gets hot or something is blocked in the crankcase.

It literally cannot be anything else 

[Radlan2]

Hi Bikerboy
        I am not sure where I posted this previously so if you have already read it apologies. I had this problem and it turned out to be the oil pump not sealing/seating correctly. I am sure you have checked that but hear me out it might be worth visiting it again. I found that the washer 67-0645 between the worm pinion and the pinion gear on the crankshaft was too thick touching the body of the pump and holding it off its seating. The same thing could in theory happen if the main bearing flange is too thin or the crank its self worn positioning the crank further out towards the timing side. There is not a lot of room in that area, perhaps as it seems to happen when it gets hot and things expand two gaskets under the pump and front fixing point could be used to move the pump a bit further away from the crankcase, worth a try?

[Sakura]

I wonder if the problem is as simple as the return side sucks air intermittently when hot rather than oil. So, what could cause that? In that case it has got to be before the pump, and there's not much there. Pick up, crankcase wall, pump seating whatever. I just don't see anything else and that would explain all the symptoms. I'm aware this is not an answer but I wouldn't be sidetracked by anything else.

[berger]

stab in the dark because i like the dark side. have you got a powerfull sump drain plug magnet and as the oil thins with heat the magnet holds the ball down in the return pipe. ok i will go back to my beers

[Swarfcut]

  I had exactly the same problem years ago with a discarded Z A7 Series crankcase. Built up a motor which ran fine until one day it started to blow smoke, eventually getting worse until the sump filled with oil, the tank emptied and  contents dumped via the breather. Rebuilt, checked everything, but with the innocence of youth took heed of the do not disturb sign on the pick up pipe. Another fruitless rebuild later, same problem. Rebuilt with another set of cases, all fine.

 Not to be beaten, took out that pickup pipe for a closer look, found a hairline crack in the right angle bend. Whoever was on pick up pipes in 1952 had managed to put the bare minimum of weld on the joint. Probably a good few out there like this from the same shift.

 It's the top one pictured.

 Swarfy.

[bikerboy]

stab in the dark because i like the dark side. have you got a powerfull sump drain plug magnet and as the oil thins with heat the magnet holds the ball down in the return pipe
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It does not have a magnet pickup in the sump but thank you for the suggestion

I have stripped it right down and have removed the sump pick up pipe. Unfortunately it appears ok but I am going to heat it up with a blow torch tomorrow in case a crack reveals itself.

I kid you not at this point in time I am still totally baffled and I have owned and been rebuilding A10's for over 50 years. This is actually the bike I took my test on over 50 years ago (yes it had a sidecar on at the time for you legal eagles lol)

I have not done 100 miles on it since the rebuild over 5 years ago due to this problem and this and every time I think I have fixed it I put it back together and it does the same thing 10 miles later. I keep parking it up and using my other bikes until I eventually get the enthusiasm to try again.

Thanks for the suggestion on the distance washer I will check that out

[Sakura]

I feel for you, I really do. You seem to have covered everything, common and unusual. Do make sure you follow through the whole of the return system looking for intermittent blockage material. Rubber oil pipes have been known to have a dislodged piece that acts as a one way valve. I've had that on a petrol pipe (car). Perhaps a bit of debris somewhere? It's got to be something, however obscure.

[bikerboy]

You seem to have covered everything, common and unusual
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Yes its totally freaky the problems I have had with this bike but I have found a place that will check and recondition the oil pump so with a bit of luck he will be able to tell me if the scavenge side of the pump is breaking down when it gets hot which should eliminate that concern.

Having said that its the 3rd pump I have fitted and one of them was tried and tested on one of my other bikes and it still got the same results

[muskrat]

Having said that its the 3rd pump I have fitted and one of them was tried and tested on one of my other bikes and it still got the same results

So it's not the pump! 
Without going back to page one. The rocker banjo bolts are correct? There some sold where the holes are too big so the oil supply overwhelms the scavenge.
Cheers

[bikerboy]

The rocker banjo bolts are correct?
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They are right I checked them for size

[Swarfcut]

 Reckon that another set of cases would decide this once and for all. Does the return to the tank falter as the engine warms up? If it does I would suspect a lack of scavenge. If the return remains good and strong, then it is more a measure of over supply. The crack you found may not be the only one.....there is a lot going on around that oil pump and its sealing face. Any restriction in the oil line past the rocker T off will result in increasing amounts of oil circulating directly back to the sump, coincidently accumulating the longer the engine runs and warms up. Blockages in the oil tank return pipe are rare but possible and easily checked.

 Pick up pipe was originally "cemented" into the crankcase. These days Loctite does the job.

 If you consider the present cases to be "scrap", and a lot spent on line boring a new bush, you have nothing to lose by simply transferring  the new bush and bearings to another set of cases, chances are it will be fine. Remember the outer face of the bush needs to be an oil tight fit in the crankcase, a leak here is another source of over supply and low oil pressure.

 Swarfy.

[bikerboy]

Reckon that another set of cases would decide this once and for all
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I thought this about 2 years ago but just to let you know at no time does the oil not pump back to the tank and it does not appear to splutter at any time. The time I got it to happen in my workshop and not on the road I was alongside it watching the oil circulation none stop.

I have been keeping my eyes open on ebay and at jumbles for a set of plunger cases but so far no good. I did, yet again, blow all the oilways in the crankcase out again and no sign whatsoever of a blockage of any type. I removed the scavenge pipe and put a blowtoch on it to see if there were any cracks that opened when hot but there were not and even connecting an airline to it there is no sign whatsoever of a leak. I am sending the oil pump away for a recon and when I get it back I aim to bolt it on the case to see if there is any sign of a leak from the mating surface.

Unless I manage to pick up a set of cases I guess its rebuild again and see how it goes

Thank you everybody for your help and time

[bikerboy]

As I am double, treble, quadrupal checking every part of this damned motor in an effort to track down why it does what it does can anybody remember the size the little holes should be in the rocker box oil banjo bolts.

I think its 1/64 but am not certain

[muskrat]

G'day bb.
1/64" sounds right for both inlet & exhaust sides. Apparently the SRM banjo holes are bigger 
The problem with bigger holes is oversupply to the rockers and it drains down to the sump. Over 15-30 minutes that overwhelms the scavenge side of the pump and fills the crankcase to blow out the breather. Just like your problem.
Cheers 

[KiwiGF]

As I am double, treble, quadrupal checking every part of this damned motor in an effort to track down why it does what it does can anybody remember the size the little holes should be in the rocker box oil banjo bolts.

I think its 1/64 but am not certain

Just a dribble of oil to the rockers on my A10, I actually think the small bore copper pipe leading to the rockers has a big if not biggest affect on flow