EW Crankcase pressure.

[Stuart Lister]

Please can somebody explain to me how crankcase pressure is (or should be) relieved on an EW?

I'll tell you why I ask. The restoration was completed, (apart from a few details) a few months ago, and ever since then, I have had no trouble at all in getting the engine to start. But after a few seconds it cuts out. I have spent hours trying to figure out why; timing seems OK (It kicks back if I don't retard the ignition, and it starts easily if I do.) The carb seems fine (It's an Amal which is wrong for an EW, but Douglas were fitting this carb to nineteen thirties models with essentially the same engine, so I think it should work at least as well as a B&B model.) And the valves are not sticking as far as I can tell by looking.

The other thing I have noticed is that it leaks a ridiculous amount of oil during the short time it runs, so I tried taking the oil line out of the front cylinder to stop this. Guess what? the engine starts and runs without cutting out. I can only assume that crankcase pressure is building up to the point where it is opposing the piston on it's downward stroke.

Clearly I need to fix the crankcase pressure problem, but where is the relief valve on this engine? Was it ever any good in the first place? would I be better off drilling and tapping the case and installing a valve of my own? Has anyone else had a similar problem?

Thank you,

Stuart

[bazza]

Hi Stuart,I have the same problem the engine runs for about 1 or 2 minutes and then for no apparent reason the engine suddenly stops and the out comes the oil.So what did you do to stop this problem,tomorrow I will try with out the front one way valve and see what happens.I did notice a hole in the base of the timing case I blocked it off did I do the wrong thing,should unblock it if I did will it spew out oil as I'm driving along ????.

Regards Bazza

[Doug]

There are two easy ways for the harmful vapours to escape the EW crancase. Primarily the crankcase vents to the timing chest. I the bottom of the timing chest, is an overflow tube (the one Bazza mentions is plugged off.) This sets the oil level in the timing chest sufficiently deep to lubricate the timing gears, the excess is drained off an led by a tube over to drip onto the primary chain. The overflow also vents excess pressure.

If this is blocked off, the opening for the exhaust valve lift cable in the original configuration is hardly a gas-tight joint. Beyond that it will try to escape anyway it can; out through the drive side main bearing, cylinder base joints, tappets, magneto drive, etc.

If there is that much pressure developing such that it stops the engine, it sounds as if the rings are not sealing very well. Running without the oil line connected to the front cylinder will eventually starve the engine for oil. The oil lines to the timing chest just lead oil to the pump and return it to the sight glass on the top of the petrol tank.

You may be putting too much oil into the engine, and it is using all its meager power to thrash it out of the way of the crankshaft?

-Doug

[roy]

Hi Barry, if its any help, I run my EW with the oil regulator tap open about one and a half turns.
I start the engine with the tap from the tank shut, let it run for approx one minute then turn it on.

Roy.