Hi,
Me again. Has anyone fitted a new SRM oil pump and noticed over oiling of the rockers? As these pumps are of a greater capacity and efficiency is this a real possibility?
Dave.
I have used the SRM pump on my A10 since 2009, and before that the SDD iron pump from 1994, which used the same high capacity gears with no sign of any over oiling.
I think the SRM and SDD pumps both use the same design gears as the late A65 cast iron pump.
Well I have a SRM pump in my RGS rep and I have found that even tho I have had the cylinder head refaced and the rocker box as I had them off about 5 times with oil leaking out from between them. Now if that is anything to do with over oiling I don`t know but it do seem Strange...... I will be getting her out of Hibernation this coming week so when i do an oil change that will be one more thing to keep an eye on as I am changing the 20/50 oil to straight 50 see if that will do anything.....but as I say.....it is a bit of a possibility that the pump may be given more oil than it needs...... Oh I was also lucky last year as the pump sheered off and had to send it back and they had to repair it and they never said why it done that.......lucky I was Not out riding at the time or would have been a Major problem in righting off the engine......done the Normal thing and looked in the oil tank and no oil coming back to tank as I say lucky ha.............. Maybe why the never charged me for the repair as they must have been a fault with that Pump :(
sounds like the same issue norton owners have with the 3 to 6 start oil drive pinion off the crankshaft.
some of those owners use a adjuster in the feed pipe to the rockers to find the optimum oil supply without smoking and leaks.
are Might have to Try that out on my Norton as that also has a SRM pump too
Hi,
I did consider that the filter in the oil return could be contributing to this as the new pump is now scavenging more efficiently but the rocker feed is after the filter so that is not the case here.
One other thing is that I have always used a Gold Star rocker feed screw/bolt on the exhaust rocker. This for no other reason than than as an inexperienced youth this is what I found on my A10 so thought that this was correct and was to feed more oil to the hotter exhaust side of the rocker box.
Now, due to the much improved pump, is too much oil getting through and I need to replace the Goldie rocker feed screw/bolt for a standard A10 one?
Once the bike is running again, perhaps tomorrow, I will have a look and see what is happening.
Dave.
Quote from: DAVE BRADY on 21 Apr, 2024, 10:58
Hi,
Me again. Has anyone fitted a new SRM oil pump and noticed over oiling of the rockers? As these pumps are of a greater capacity and efficiency is this a real possibility?
Dave.
What problems are you getting that you think could be down to over-oiling?
Hi Dave
I have been using the Goldie type rocker bolt on the exhaust for many years and have not had any oiling problems with it.
There always appears to be a lot of oil in the box, which I think good because it drains down and provides plenty of lubrication to the cam and followers.
I had oil leaks, head to rocker box, due in part to the bad shape of the inlet gasket at the front between the bolts not being wide enough. Overcame this leak by having the questioned joint on the box built up with ali weld to widen it and then ground back, then lapping box to head and using an SRM rocker gasket. There is a lot of rocking pressure on the gaskets and I found some of the thicker ones actually squeezed out from the joint due to not being sufficiently resistant to being compressed between the surfaces.
My setup, on an SRM end feed engine is SRM pump and PRV, Morgo filter in the return line, rocker feed via a Webco cast manifold.
Hi,
There is oil in the exhaust. This is unburnt so unlikely to have gone through the combustion chamber and the exhaust was not smokey. There was a problem with a sticking inlet valve that may have contributed.
Part of my thinking as regards over oiling was that if the oil delivered to the exhaust was not draining quick enough it is possible that it could rise to level were it could get down the valve guide. The drain holes are clear.
A further complication is that I am fitting a 2mm head gasket to lower the compression a bit for easier starting and I now suspect that this may be playing a part in this saga. Annealing a standard gasket is quite easy but the extra thickness seems to take lot more to get it to cherry red.
I have now achieved this using a MAP gas torch.
It is possible that the gasket had not sealed properly. So I am going to use some Wellseal on the now properly annealed gasket as an extra sealing agent. Perhaps a few more ft/lbs of torque will also be a good idea.
I will know the outcome of all of this over the next couple of days.
Dave.
I have had an unending battle to stop an oil leak from the rocker boxes in my ally head A10. In the end I gave up as other than a bit of mess on the head it didn't affectr anything.
However I have just come back from a fast 80 round trip to find it leaking worse.
On a couple of occassions the bike hesitated at speed but then picked up again.
On getting home I found the plugs drenched in oil from the rocker box.
It wasn't this bad before I fitted the SRM pump and my other A10 with ally head but original pump doesn't leak. ???
Hi Dean,
Last time you had the rocker box off did you check it for flatness across the faces. Ally heads need to be checked as well. Have you got a breather on the rocker box?
I think I have always had a breather on the rear rocker cover. At first I noted that it was possible to get bits drawn up the tube so I used a valve from an old inter tube. The 'one-way' allows the pressure out and prevents any return suction.
Dave.
Dave
since posting I have been thinking about fitting a rocker breather. I've only a short time to sort it before I cross the water so probably a quick lash up involving a hollow bolt and long length of tube.
I need to investigate 'Bunn breathers' some time.
But its reassuring that you suggest a breather. Thanks
PS I did text/phone you today but perhaps I have the wrong number
Hi Dean,
Simplest way is to use and old valve from an inner tube. Drill a hole in the middle of the rear rocker cover and put the valve, minus the inner bit, through from the inside and use the locking ring or nut on the outside with a fibre washer. The bit of rubber left on will seal the inside. Then a bit tube to wards the rear of the bike.
Dave.
Thanks Dave, I'll try that
Quote from: Dean Southall on 02 May, 2024, 19:16
Dave
since posting I have been thinking about fitting a rocker breather. I've only a short time to sort it before I cross the water so probably a quick lash up involving a hollow bolt and long length of tube.
I need to investigate 'Bunn breathers' some time.
But its reassuring that you suggest a breather. Thanks
PS I did text/phone you today but perhaps I have the wrong number
Dean, forget the Bunn breather for reasons below.
The crank case pressure needs to run under a negative pressure, not only will this aid ring sealing, it will also help keep the oil in the crank cases. When the timed breather opens (or even with a reed valve breather on the outlet) any positive pressure is pushed out on the downstroke. On the ascending stroke the timed breather or reed valve is closed, on the following series of engine strokes the amount of pressure exiting the cases is minimal as the only positive pressure created is the expansion from gasses as they are heated.
As soon as you start adding air into the engine, it becomes an air pump, it will also pump oil out. And may blow some oil seals in the process.
I didn't realise how important these above points were until I ran an open breather on my 823cc Thunderbolt. It blew the DS oil seal and pumped out half its engine oil. It may have also affected its ring sealing. A new DS seal and blanked the additional breather off and the bike is fine, even with the standard camshaft timed breather.
Another and very important thing to note is when you introduce cold air into an engine (like with the Bunn breather) the cold air forms condensation with the hot oil. This then becomes acidic, which breaks down the oil and harms engine components.
True. Everyone assumes that the old British factories knew little or nothing about breathing when the opposite is more accurate, and while adding additional breathers may help in some circumstances they're not a cure-all for other engine problems.
About 18 months ago I determined to reduce the rockerbox oil leaks on my iron head A10, having tried various methods as detailed below. I checked the metal to metal joint by removing the rockers then bolting the box to the head and then checking for the gaps. The worst gaps were on the outside of the exhaust compartment.. With head removed from bike and valves out I lapped the box to the head, quite labourious, but the result is no leak after sealing the joint with an SRM gasket ane Wellseal.
Some gaskets are not quite the correct shape especially at the front of the inlet compartment giving a narrow joint. Some gaskets do not seem to resist being squashed when the fixings are tightened and seem to settle and appear to need to be retightened. When retightened the gasket starts to creep out from the joint. Leaks follow.
I tried the simple version of Bunn, really just a rocker breather with a non return valve similar to an aquarium air pump non return valve. It did not seem like the valve could keep up with the engine. I tried a rocker breather on a Dow finned cover, both with the original small bore outlet and with a much larger one. Not convinced that it helped. Tried a breather on both covers. The same result.
I sealed a freezer bag to the Dow breather tube, expecting it to slowly inflate when the engine ran. Well it did not, it seemed to suck a little more air in than it expelled.
Those breathers now blanked off. Not needed following the work on the joint.
Hi,
I salvaged another valve from an old inner tube and threaded it into the open end of the tube from the rocker box. This has been in place for many year/miles and still works. When the engine is running a flow of 'air can be felt but no obvious oil vapours being emitted. Almost like the std timed breather.
As the engine can suck as well as blow the valve serves to keep out fresh air and any muck that could find its way up to the rocker box - I had noticed this in the past.
Dave.