I actually rode my new bike today for the first time, just around the yard, it goes really well and shifts through the gears nicely. I left it ticking over for a while and noticed smoke coming from the engine, it looked like oil was coming from the head gasket on the left side. I shut it down and the oil soon burnt off. The funny thing is is that it seems to be fine now, no more smoke of leaking. What can it be ? :-\
(https://i.imgur.com/rvP4aoKh.jpg)
(https://i.imgur.com/BHbGT16h.jpg)
(https://i.imgur.com/2Vbpb56h.jpg)
Hi Mick,
When you say it seems fine now does that mean that even when running there is no longer a leak?
Perhaps running the engine has helped the gasket to seal.
I notice that there are no washers under the head nuts. Is it possible that the previous owner left them off and were they left off the bolts as well. It may be OK but washers are specified for the head fasteners. The other thing is that if the gasket has not long been fitted it may need the torque checking. A fiddly job but worth doing.
Dave.
Quote from: DAVE BRADY on 13 Mar, 2021, 20:13
Hi Mick,
When you say it seems fine now does that mean that even when running there is no longer a leak?
Perhaps running the engine has helped the gasket to seal.
I notice that there are no washers under the head nuts. Is it possible that the previous owner left them off and were they left off the bolts as well. It may be OK but washers are specified for the head fasteners. The other thing is that if the gasket has not long been fitted it may need the torque checking. A fiddly job but worth doing.
Dave.
I just took it for a fast spin on the open road, when I got back it was leaking again but not as bad as before, there is oil on a head nut, I think it's the one you noticed has no washer. I have no spanner that will fit that nut, do you know what size I need ?
A problem where i live is that it gets really cold at times, I have seen it as low as -43 C this winter, it makes metal contract.The bike has not been running for several years.
Hi,
It is 3/8 BSC / 3/8 BSF spanner. There is no washer under either nut visible in the photo so it may be worth checking the other side. Oil coming up the stud does indicate that the gasket is not sealing properly.
As the engine has not been run for a while it may be worth checking that the head is torqued down properly and take the opportunity to fit the correct washers. The only way to this is to remove the rocker box and do all the bolts. The workshop manual covers this and gives the sequence for tightening the head down. It is probably worth getting some spanners and sockets. Imperial and AF spanners are available as well as sockets but buy good ones and they will last for ever.
Dave.
Thanks Dave, I will do as you suggest.
PS What des BSC and BSF stand for ?
Hi
BSC is British Standard Cycle and BSF is British Standard Fine. I think that you will find suppliers in the USA.
It may be more convenient to get them from there rather than from the UK.
There is a Canada BSAOC. The contact is :- Barry Mitton 5 Appletree Court, Simcoe, Ontario, Canada N3Y 4V1 email :- 1963rocketgoldstar@gmail.com
I know Canada is a big place but there may be BSA owners not too far from where you live.
Dave.
Quote from: DAVE BRADY on 13 Mar, 2021, 22:06
Hi
BSC is British Standard Cycle and BSF is British Standard Fine. I think that you will find suppliers in the USA.
It may be more convenient to get them from there rather than from the UK.
There is a Canada BSAOC. The contact is :- Barry Mitton 5 Appletree Court, Simcoe, Ontario, Canada N3Y 4V1 email :- 1963rocketgoldstar@gmail.com
I know Canada is a big place but there may be BSA owners not too far from where you live.
Dave.
Thanks Dave. I will drop Barry Mitton a line, he is practically a neighbour, he only lives 3 time zones away. :)
Are these Witworth spanners what I need to work on my BSA ?
https://www.amazon.ca/8pc-Whitworth-Spanner-Silverline-SIL8/dp/B01M332ZQ1/ref=sr_1_1?crid=TWFSET3EZEFQ&dchild=1&keywords=whitworth+wrenches&qid=1615691892&sprefix=witworth%2Caps%2C258&sr=8-1
a good source of information closer to you https://www.baxtercycle.com/ alternatively https://www.classicbritishspares.com/collections/tools
Hi,
Also E&V Engineering in Howard City just over the border in the US. As they work professionally on BSAs it may be worth asking them to suggest a tool kit and a make and supplier for the spanners. The nuts and bolts on a '69/'70 will have some BSF fasteners but will also have AF. BSW and BSF spanners can be used on either although the sizing is different. It is possible that someone will come on with a list that would help.
A bit of an aside is that even a relatively small country like the UK used to have different time zones based on sunrise. It was not until the establishment of the railways and the need for a time table that the country really had the same time. A reliable clock set to GMT put on the train would be used to set the clocks along the way.
Dave.
Hi,
Dave correctly mentioned the need for washers under the head fixings.
To expand, BSA in 1970 identified an issue and further improved the head gasket seal by using thicker washers, part number 02-0861. If you cant source originals check what's available and that they are at least OD 0.750", ID of 0.380" and a thickness of 0.092".
Bes wishes...
There's a lot of inormation here, but I'm still confused about the spanners I need to get. Will Witworth spanners do the job ?
I will make sure to fit the correct washers Bess, but how thick washers under the head nuts can improve the head gasket seal is beyond me.
Thanks :)
Hi
Whitworth/BSF spanners will fit some of the nuts and bolts but a set of AF spanners will probably be needed as well.
Dave.
It is a bit confusing! The CEI threaded components that we have on BSAs (mainly 26 TPI but also 20) need Whitworth size spanners. The spanner size relates to the shank diameter not the head.
BSF/UNF/UNC spanner sizes all relate to the measurements 'Across Flats' (AF) so use common spanners although they have varying thread profiles.
To make it more confusing, there are some sizes where one spanner size is near enough to fit both Whitworth and (e.g.) BSF.
This link may clarify! http://classicmechanic.blogspot.com/2011/06/mm-af-bsw-bsf-spanner-conversion-chart.html
My suggestion would definitely be to invest in a set of Whitworth spanners.
Finally.... You will find that you can't get a socket on to some of the head nuts and an open-ended spanner can't get the torque. In which case I suggest getting one of these: https://www.amazon.co.uk/gp/product/B00BH3QVA2 it's metric but adjusts to grip and does a good job!
Cheers,
Bernie
Re the washers and their effect on the head gasket. Without a washer the nut cannot be properly tightened as the aluminium head under it will distort. The thicker the washer the less deformation there is in the washer which allows the nut to be torqued down much better thus giving much more compression on the gasket resulting in a better seal.
Hi Mick,
A thicker washer amongst other functions, spreads the face pressure over a larger surface area hence increasing the effectiveness of the gasket.
Best wishes...
Today I've been educated thanks.
Quote from: berniej on 14 Mar, 2021, 18:16
It is a bit confusing! The CEI threaded components that we have on BSAs (mainly 26 TPI but also 20) need Whitworth size spanners. The spanner size relates to the shank diameter not the head.
BSF/UNF/UNC spanner sizes all relate to the measurements 'Across Flats' (AF) so use common spanners although they have varying thread profiles.
To make it more confusing, there are some sizes where one spanner size is near enough to fit both Whitworth and (e.g.) BSF.
This link may clarify! http://classicmechanic.blogspot.com/2011/06/mm-af-bsw-bsf-spanner-conversion-chart.html
My suggestion would definitely be to invest in a set of Whitworth spanners.
Finally.... You will find that you can't get a socket on to some of the head nuts and an open-ended spanner can't get the torque. In which case I suggest getting one of these: https://www.amazon.co.uk/gp/product/B00BH3QVA2 it's metric but adjusts to grip and does a good job!
Cheers,
Bernie
BSF use the same spanners as BSW. For post war fasteners, the same diameter thread in both BSW and BSF use the same spanner size. Prior to that, the Whitworth fastener would have a bigger head than a BSF fastener of the same diameter. Hex sizes were reduced to save material, and never changed back. What makes it confusing is the markings on spanners never changed - even brand new ones will say 5/16" Whit for example, when in fact it will fit a 3/8" Whit bolt and nut (and 3/8" BSF, which the spanner will correctly state)
Unified series threads (UNF/UNC etc) use AF spanners, as you say across the flats sizes.
CEI (later adopted as BSCy) should use BSW sizes for the head flats, but I've found a mix on aftermarket nuts between BSW and AF size hex (should be the former on standard fasteners)
Quote from: Pete A10 on 14 Mar, 2021, 18:58
Re the washers and their effect on the head gasket. Without a washer the nut cannot be properly tightened as the aluminium head under it will distort. The thicker the washer the less deformation there is in the washer which allows the nut to be torqued down much better thus giving much more compression on the gasket resulting in a better seal.
I have the correct washers on the way. Thanks for the info !
I've got the same leak on my A50.
Rebuilt the engine , new head gasket, same leak still present in the same place as yours.
Only leaks when on the side stand and engine running. It can tick over on the centre stand for 5 minutes with no leak.
Hi,
This seems to be a recurring theme. One of my A65s did this when I got it. It was not really a problem but more annoying than anything else. I cleaned the joint and made sure it was dry to see exactly where the oil was coming from. The main area was on the front to the left hand side and nothing elsewhere. Eventually I did change the head gasket and it stopped. Although there is still a hint of oilyness on the joint it is not enough to run and drip. I think the main culprit is where the drain holes are near the exhaust valves. If the head is not perfectly flat and the gasket not torqued properly this seems to be the spot that leaks. At some point, officially or unofficially 'O' rings were fitted to solve this. The hole in the gasket is big enough for an 'O' ring to be squashed by the head and make a good seal. I have done this on both bikes recently but have not done enough miles to say if it works long term.
Dave.
:) :) :)
I am about to reassemble an A65 as a result of the same problem. oil was bubbling up alongside one of the head studs. Maybe partly my fault as a result of a bad torqueing of one bolt, but strangely on the opposite side of the head. Who knows we'll have a better idea tomorrow????????
Mike 8) 8) 8)
Hi,
A slightly different issue as that indicates that gasket has not sealed around the stud. So along with very clean threads to ensure proper torquing it is worth making sure that the gasket is perfectly flat around the holes. They appear to be stamped out and this can cause slightly raised edges on what I would call the underneath of the gasket so remove any burrs or raised edge.
I think with all of these things it is marginal gains to get the best result.
Dave.
Quote from: DAVE BRADY on 16 Mar, 2021, 08:05
Hi,
This seems to be a recurring theme. One of my A65s did this when I got it. It was not really a problem but more annoying than anything else. I cleaned the joint and made sure it was dry to see exactly where the oil was coming from. The main area was on the front to the left hand side and nothing elsewhere. Eventually I did change the head gasket and it stopped. Although there is still a hint of oilyness on the joint it is not enough to run and drip. I think the main culprit is where the drain holes are near the exhaust valves. If the head is not perfectly flat and the gasket not torqued properly this seems to be the spot that leaks. At some point, officially or unofficially 'O' rings were fitted to solve this. The hole in the gasket is big enough for an 'O' ring to be squashed by the head and make a good seal. I have done this on both bikes recently but have not done enough miles to say if it works long term.
Dave.
I have noticed when the bike is on the center stand that the exhaust is a slightly smoky on the leaking side, maybe it's leaking internally too ?
Hi Mick,
It is possible that some oil is being drawn into the combustion chamber. Check the plug but also consider that there could be a worn valve guide or bore but if the engine has not done enough miles after a rebore it could be that the rings are not quite bedded in yet. If you are going to fit the washers then as you will have the head off check everything.
Dave.
Quote from: DAVE BRADY on 16 Mar, 2021, 11:45
Hi Mick,
It is possible that some oil is being drawn into the combustion chamber. Check the plug but also consider that there could be a worn valve guide or bore but if the engine has not done enough miles after a rebore it could be that the rings are not quite bedded in yet. If you are going to fit the washers then as you will have the head off check everything.
Dave.
There are washers under the bolt heads beneath the rocker box cover but they look like ordinary washers, they are not thick.
My bike was made in 1968, but if memory serves you said earlier the thick washers were introduced in 1970 .
I'm wondering if I should mess with the bolts under the rocker box cover. What do you think ?
Hi,
I would think it best to a least re-torque all the bolts as you will be undoing the outer nuts and then torquing them again. There is a sequence for tightening in the handbook and it is worth following this for undoing a bit in order to re-torque.
Dave.