Engine breather

[Mike Farmer]

 

Hi. My engine breather is almost pouring oil.(I didn't do the assembly) but I wouldn't Be surprised if there timed breather is assembled wrongly. As I dont have the time etc to pull the engine to bits I am considering putting a breather on the crankcase as shown by the spot in the pic then passing a pipe back direct to the oil tank (after blocking off the existing breather) however not necessarily from that exact point

Mike

[Mike Farmer]

 

Forget to say there are several position options. Would an outlet on the rocker cover be an option ??

Mike

[DAVE BRADY]

Hi Mike,

I do not think I would drill a hole there, right were the barrel studs are.  The rocker box is a good option as it has direct access to the crank case but does not get too much oil up there. 
If the breather is timed wrongly then it usually results in the crank case pressure under the descending pistons causing oil to force its way through joint surfaces and seals as the breather is not opening at the right time.  I think, in theory at least, a wrongly timed breather would possibly have a 'suck' as the breather could open when the pistons are rising and causing a partial vacuum in the crank case.  I know it would be a pain but perhaps a proper fix would be better.

Dave.

[Spaceman]

Hi. My engine breather is almost pouring oil.(I didn't do the assembly) but I wouldn't Be surprised if there timed breather is assembled wrongly. As I dont have the time etc to pull the engine to bits I am considering putting a breather on the crankcase as shown by the spot in the pic then passing a pipe back direct to the oil tank (after blocking off the existing breather) however not necessarily from that exact point

Mike

I think your problem may not be as simple as a wrongly assembled breather?

The engine breather works by opening the rotary valve as the piston descends to stop the increasing crankcase pressure from forcing oil out through seals, mating surfaces etc. In this case, the problem may be that too much oil is getting on to or into the LH camshaft bush and the breather is simply doing its job but the escaping air is taking too much oil with it.

Possible reasons for this could be a worn bush or too much oil being thrown around the crankcase especially if it is not being scavenged properly back to the oil tank from the sump. An alternative breather in, say, the rocker cover could prevent the oil loss but may not address the cause of the problem?

[DAVE BRADY]

Hi,

This has just reminded me about a similar issue with an A10.  Lots of oil quite suddenly started coming out of the breather and some exhaust smoke whilst riding along.  Upon investigation it was found that 'popeye's pipe' in the sump had come out of the case.  This obviously allowed the oil level to rise before being scavenged and the flywheel picked it up and the result was lots of oil from the breather and too much oil for the rings to cope with.
So, worth checking that the scavenge pipe is still in place.

Dave.

[Mike Farmer]

 

Hi each. The point about the popeye is a very good one that I have foolishy not considered. I have an inline oil filter fitted and wonder if this is making a difference. (SRM say don't fit one).

There are several other places to fit a return pipe. I have a spare engine that I could shove in and then bite the bullet and strip it. I'm old enuff that biting the bullet no longer appeals as much as it once did. So I dont want to go down that line if avoidable. If my memory serves me right the cam shaft bearing is new. The engine was rebuilt about 5 years ago and has only done about 30 miles since.

So keep the ideas/thoughts coming for me to consider. Anything to delay what appears to be the inevitable. We'll see.

Mike

[DAVE BRADY]

Hi Mike,

The filter should not have any affect.  I have used them on two bikes with over 200,000 miles between them.
If the oil is getting back to the tank as it should then no problem with the filter.
Has it just started doing this or was it from day one? 

Dave.

[Spaceman]

I would definitely check the oil is returning back to the tank as it should - continuous flow when you start up the end changing to spurting as the pump clears the accumulated oil in the sump. If ok, unfortunately, the next check would have to be that the scavenge pipe poking through the mesh filter in the bottom of the sump is ok and hasn't been displaced. If that is ok, I would be temporarily remove the inline filter to free up the return flow and see if that makes a difference.

However, it would be useful to know a bit more about the history of the problem especially as this engine has not done very much in the 5 years since it was rebuilt. For example, has it been left for long periods filled with engine oil and, if so, did you have to drain this out of the sump before attempting to start the engine after the last lay up?

[DAVE BRADY]

Hi,

I am not a filter expert but I believe that they vary quite bit hence the wide variety that are available.  Some may offer more resistance than others and may not be suitable for the low pressure return on a BSA.
Currently I am using Wix WL7101 on three bikes.  I think the number is more important than the make as I have used Champion and Purolator in the past.  Worth checking just in case.

Dave.

[Mike Farmer]

 

OK lets try to answer each Q.
Did it do it from day one----yes.
Is the oil returning to tank as expected----yes
Does it wet sump----No I have an anti wet sump valve fitted.
Is the return suction pipe correctly fitted ---- let you all know as soon as.
Does it blow smoke----No
Where else could the oil be coming from----?? Gearbox main shaft oil seal---yes but oil does not feel right for that and my experience is that if that seal is dodgy it drips. I do not have a drip problem--well some mornings, but thats manageable. Cracked casing---now that really would be time for a very senior moment. Teddy bear right up on the neighbours roof.
Am I that bothered----Nope. As Ive said I cant ride it, but it just aint right.
So gentlemen of the Beesa Fraternity. Thinking caps please.

Mike

[Spaceman]

I think this issue has come up before and part of the problem is trying to work out where the oil is coming from. There are at least 3 possibilities:

1. Chaincase oil getting past the seal in the back of the case

2. Gearbox oil getting out past the seal on the main shaft or under the sleeve gear

3. Engine oil coming out of the breather

In each case, the problem may only manifest itself when the engine is running rather than with the bike standing idle because it is oil being thrown about by the moving parts that ends up seeping out. One way of working out which type of oil is leaking out is to dye it which you can sensibly do to the chaincase and gearbox oil.

Unfortunately with the A65, BSA chose not to connect a pipe to the breather outlet which would have made it much easier to work out if this is the source of the current problem.

[DAVE BRADY]

Hi,

As Mike says "My engine breather is almost pouring oil." I would think that it is the breather.  In my experience leaking primary case or gear box seal/shaft tend to dribble rather than pour.
I am just going out top the shed to see if it possible to view the breather outlet with a mirror (no smoke) and torch........
No! Not possible.  Perhaps one of those little cameras on flexible stick could get in there.

Dave.

[Mike Farmer]

 

Thanks guys.  I'll have another look later. Its probably some little git with an oil can.

I suppose it could also be coming from the oiler in the rear of the chain case, but realistically that should only mist at most.

Mike

[Spaceman]

Unfortunately, BSA put the breather outlet hole just in front and above the gearbox sprocket making it very hard to tell where any oil leaking down from the vicinity of the sprocket is coming from. There have been cases where the LH crankshaft oil seal has failed allowing oil to be pumped into the chaincase from the engine and then being forced out again near the gearbox sprocket.

To rule out the problem being oil from the chaincase, simply requires the oil to be drained out of it to see if this makes a difference. Rather than using dye, you could also drain the oil out of the gearbox and, again, see if this stops the problem - there's no problem running the engine in this state for a short while.

I've never tried it but it may also be possible to run the engine with the rocker cover off which I would have thought would stop air being forced out of the breather and prove one way or the other whether that is where the leak is coming from!

[Mike Farmer]

 

Since my last post I have used a torch and my fone and up-crancased my engine. Not a sign of an oil drip from the breather, The casing is as good as pristine. This is a back to the drawing board problem. So much for assuming.

However---confession of the year---the "tin plate" sprocket cover is not fitted. Sadly, regardless of who rebuilt the motor this one is down to me. How do I feel---Bloody stupid. Anyone ever fitted one with engine in place?? Ho Ho Ho I think I'm going to let my wife buy me a new star cos that will be a good idea. Something else to stare at. If you listen carefully you can hear the echo of her answer drifting down the valley.

So guys thanks for your interest and though the problem remains I'm going to put this to bed for a while. Till I get my head around it.

Mike