ES2 oil leaks

Hi.

Check that there's not 50 years of crud in the screw holes. I had a similar leak from my timing case and even though the screws appeared tight they were stopped from going all the way home by compacted crud. With the cylinder base I guess it'll be a new gasket or RTV. Also check the your cylinder head bolts go all the way too although if they weren't I would have thought your head gasket would have gone as well. One other point worth mentioning is that, before the crankcase nuts and bolts are fully tightened after a full rebuild, it is worth fitting and tightening the head and barrel (temporarily). This ensures that the crankcase halves are pulled up 'true' so there's no step between the two halves at the base of the barrel.

The ES2 has two breathers. A timed one exiting on the left hand side under the crank's bearing housing and one with a ball valve just above the crank's bearing housing. Any oil getting past the left hand main bearings exits out of the timed breather and this is often mistaken as a primary chaincase leak! The other breather also lets a fair amount of oil out if the bike is used hard - even if the engine (and oil pump)is in good nick - and this is another 'leak' for which the primary chaincase gets the blame.

On my 1960 ES2 I have blanked off the timed breather and replaced the ball valve breatherwith an ordinary union drilled out and fitted with a larger bore pipe. This leads to the bottom of a small catch tank (about 250ml) in the tool tray under the seat. A pipe exits from the top ofthis and ends down behind the gearboxin a 'duck-bill' breather valve from a Royal Enfield. Any oil from the breather drains back to the motor the same way it came when a vacuum builds when runningor when the bike is at a standstill. I've been using this for over 2 years now, it's almost invisibleand it seems to work very well.

Cheers.

Ian.

Previously wrote:

Hi All,

My 1954 ES2 motor has developed 2 annoying oil leaks.

The first is from the front left side of the cylinder base and the other from the inner timing chest seam at the top. I have gone over the hold down bolts of both barrel and timing chest but they all seem tight.

Is this type of leak normal with this model or is this a crankcase breathing issue?

Best wishes,

Albert

Hi Albert, there is a possibility that one of the leaks , the timing chest one, is coming from the pushrod tube seals, top or bottom. My ES2 collects a little pool of oil on top of the inner timing cover which has its source from the top front pushrod tube seal. Only after a good lively run though. Might be worth considering before the spanners are applied.

Adam