To much oil pressure on 1957 M30 twin

Helpful information and requests for assitance and advice
John Grew
Posts: 39
Joined: Sat Dec 03, 2011 6:35 pm
Location: SUSSEX UK
Location: SUSSEX, UK

To much oil pressure on 1957 M30 twin

Post by John Grew »

As I bought this in a sack I have had to rebuild this with a lot of help and at times with a white stick. I now have 700 miles on the clock but from day one it has leaked oil from all the wrong places and I concluded that it was not breathing as it should.
I have always been a big believer in adding extra breathers as and when so I put one in to the exhaust rocked box as there was no other place and this made a lot of difference to the oil leaks . However it then started blowing oil out of the small pipe that I had fitted to the breather. Just as a try, I increased the size of the pipe and now it is flooding out. I have had the oil pump out a checked that I had rebuilt it the right way round and that is ok and at the moment I am wondering if I have the top hat that goes in the end of the felt oil filter the right way round or not. I don't think that there an obvious way for it to go and currently it is narrow end into the filter with the wide end up against the relief valve..
It does not smoke so I feel that the rings are ok and it has good compression and goes well.
Giss a clue.
Dazed and confused
John Grew
Mick D
Posts: 2886
Joined: Mon Mar 24, 2014 5:44 pm
Location: Aberdeenshire

Re: To much oil pressure on 1957 M30 twin

Post by Mick D »

Hi

What are the wrong places? - rather than fit breathers at random I'd be looking to discover why it was leaking from where it is.

Regards Mick
User avatar
dave16mct
Member
Posts: 3234
Joined: Mon Jan 01, 1990 12:00 am
Location: LANCASHIRE UK

Re: To much oil pressure on 1957 M30 twin

Post by dave16mct »

Here's a pic but it sounds like you've got it right. See page 18.

http://archives.jampot.dk/book/Owners_m ... Models.pdf

Why not put the breather pipe into a catch tank? A small bottle hidden away somewhere, obviously needs a vent to prevent it pressurising.

Dave.
Last edited by dave16mct on Tue May 30, 2017 11:02 pm, edited 2 times in total.
raffles
Member
Posts: 609
Joined: Mon Jan 01, 1990 12:00 am
Location: NORTHAMPTONSHIRE UK

Re: To much oil pressure on 1957 M30 twin

Post by raffles »

are you sure you have the pumps the correct way round. the smaller one fits on the right as you look at it. OR.could you perhaps have two return pumps ?
Tony
dodger
Member
Posts: 224
Joined: Sat Jan 01, 2000 12:00 am
Location: HAMPSHIRE UK

Re: To much oil pressure on 1957 M30 twin

Post by dodger »

Some models were not fitted with an oil relief valve, perhaps your 57 motor is one of those, my 1958 G11 engine does not have an oil relief valve. If yours is the same and you are using straight 40 or 50 oil this will not help on start up when you can get oil pressures over 300 psi with cold straight 40 or 50 oil.

If you are getting too much oil up the top end, around this year AMC also omitted the oil metering plugs to the rocker gear, they re-introduced them a couple of years later,

Laurie
User avatar
1608
Member
Posts: 2493
Joined: Mon Oct 05, 2009 1:00 am
Location: ESSEX UK

Re: To much oil pressure on 1957 M30 twin

Post by 1608 »

I'm always amazed at how quickly people seem to start fitting extra breather pipes etc. because the engine leaks oil. Does anyone ever consider that they might just not have put the thing together properly. The first sign of an oil leak and the extra breathers start appearing. British bikes gained a bad name through oil leaks ( as opposed to Jap bikes ) cos they were relatively high maintenance and so encouraged easy dismantling and putting back together, but youngsters playing with spanners caused the problems. Care must be taken in replacing alloy mating faces. I have re-built my G12, 18S and a '58 Ariel 650 recently ( and many others in the past) and none of them leak oil. These engines survive on minimal oil circulation to the important parts such as b/ends etc. but rely mainly on oil mist and 'splash'. If oil leaks were caused by a lack of engine breathing then the makers would have sorted that very early on. I would be interested to know where the leaks actually are. I now expect a lot of flack, but thats life.
User avatar
Rob Harknett
Member
Posts: 11236
Joined: Mon Jan 01, 1990 12:00 am
Location: ESSEX UK

Re: To much oil pressure on 1957 M30 twin

Post by Rob Harknett »

However bad the old bikes are said to be, the fact is, after 60/100 years they can still be repaired and still running. So why alter anything? The much better oil leak free Jap bikes have still to prove, they will still be running after 60/100 years.
SPRIDDLER
Member
Posts: 8542
Joined: Wed Sep 01, 2004 1:00 am
Location: WEST SUSSEX UK

Re: To much oil pressure on 1957 M30 twin

Post by SPRIDDLER »

1608 wrote:I'm always amazed at how quickly people seem to start fitting extra breather pipes etc. because the engine leaks oil. Does anyone ever consider that they might just not have put the thing together properly. I now expect a lot of flack, but thats life.
I tend to agree with you there, John. It's a similar fudge with the rush to fit electronic ignition on a mag bike as soon as there's a starting or an 'ignition' problem.
Manufacturers only replaced the self-energising virtually maintenance-free and independent magneto with the cheap 'n cheerful battery, coil and points system in order to make a significant cost saving. I do understand though how irritating it must be with mags packing up every 20 years ;)



("Corporal! More sandbags over here.....at the double!"
'There is a tide in the affairs of men
Which taken at the flood............'
User avatar
1608
Member
Posts: 2493
Joined: Mon Oct 05, 2009 1:00 am
Location: ESSEX UK

Re: To much oil pressure on 1957 M30 twin

Post by 1608 »

Thanks for the support Nev, I usually get blanked when I offer some advice, Probably 'cos I tend to be a bit on the blunt side I suppose. Hope you are keeping well, don't seem to hear from you so much of late. Back to the prob of over oiling/leaking though, do all the twins have extra breathers fitted, no. Its a bit like the problem I have with my Ariel twin, The left cylinder runs weaker than the right side. BSA ( builders of the late Ariels ) devised a Biased carburetor flange gasket to correct the problem. This is often described as a palliative remedy and only had a relatively small success rate. The problem is believed to be caused more often than not by the K2f mag cam ring being out of balance, ie, timing correct on the cylinder used to time the bike but not quite right on the other. My point being, extra breathers may ease the leakage of oil, but not correct the cause.
John Grew
Posts: 39
Joined: Sat Dec 03, 2011 6:35 pm
Location: SUSSEX UK
Location: SUSSEX, UK

Re: To much oil pressure on 1957 M30 twin

Post by John Grew »

Ok so sit there and feel smug , you have made your point ,but have you got any idea what might be causing it?
Locked