VB crankcase breather drip

[Jim Fitzgerald]

Hi
I recently purchased a 1959 VB. It had been standing for over 6 months so would not start when I first looked at it. I bought it anyway and after cleaning the mag points and plug it started ok.
Oil was returning to the tank and everything looked ok.
After it had run for a while I noticed a fast drip from the crankcase breather.
I suspected wet sumping and removed the sump plate and got about 3/4 pint of oil out.
I left the plate off with a tray underneath with oil still in the tank to check if the pump or valves were letting by and nothing more came out.
I drained the tank and flushed it out and cleaned the filter and filled up with new oil.
I started it today and oil and bubbles started returning to the tank and then the breather started dripping again.
I suspect that there is an air leak between the pump and housing and the pump return (Morgo) cannot keep the sump level down. I read somewhere that sometimes two gaskets need to be used under the pump.
Any advice would be appreciated before I investigate further.

Jim

[volker.halbach]

There are various places for air leaks. A likely place is between crankcase and timing case. There should be an extra joint washer around the return pipe. As always the book C.W. Waller: "Ariel Motorcycles" is indispensable (I think it's also in the members' area). It has two pages or so on this topic, including how to test the oil return.

[Jim Fitzgerald]

Thanks Volker.
I removed the mag chain cover to expose the Morgo oil pump and the two mounting screws were fairly tight.
There seems to be quite a healthy return flow to the tank when the engine is running but after about fifteen seconds I am getting about one drip a second from the breather.
I am running out of ideas. Perhaps I could try a new gasket under the oil pump.
Is there some sort of valve in the breather itself which will hold back the oil?

Jim

[will_curry]

Jim,

I assume you mean the breather from the crankcase on the drive side.

3/4 of a pint is rather a lot of oil to have in the sump. If there is an oil leak
in the pickup pipe from the sump to the pump return the return flow of
oil will look as it should but the oil level in the sump will be too high and
oil will get pumped out of the breathers. I have found leaks where the
pickup pushes into the crankcase and I've also found a pair of cases where
someone had shortened the pickup pipe - goodness knows why.

[Jim Fitzgerald]

Hi Will.
Yes I am referring to the drive side breather. The other two are dry.
I have just removed the sump plate and about 3/8 of a pint came out. I wiggled the pickup pipe and tried to pull it out and it seemed quite firm. The bottom of the pipe was just below the flange on the cylinder base so looks to be the right length and pokes through the mesh filter when the plate is fitted.
I am out of ideas at the moment. I have a VH in the garage so I may take the pump off that and replace the Morgo and see what happens. Perhaps the Morgo is over oiling.
While the pump is off I will give the oilway drillings a flush out and check the springs and balls behind the pump.
I have ordered two pump gaskets to see if that makes a difference.
Do you know if the drive side breather has any sort of valve like a ball and spring to stop so much oil coming out.
I am getting about a drip a second on tickover.

Jim

[JohnnyBeckett]

hi that is what i have done is fit a new Morgo pump and the oil flow and return is very good

[paul.jameson]

You need to read Waller to see the illustration of where the two gaskets go. This is between timing case and crankcase, not directly behind the pump.

[will_curry]

Jim,

A banjo union and bolt secure the breather into the crankcase and there is
no valve or anything like that.

The pipe sounds to be OK but I'm not too sure about 3/8 of a pint though.
I'm pretty good on pints and happy enough with halves but 3/8 in a sump
is perhaps rather more than I'd expect.

Somewhere on the forum there some other posts about how much oil to
expect in the sump but I can't remember where at the moment.

Apart from the occasional problem with debris in the return valve I've had
no real trouble with the original Ariel pumps and I've no experience with
Morgo pumps.

Does the engine burn oil?

[Roger Gwynn]

I suppose it is a Morgo pump for an Ariel and not a Triumph one, the big plunger should be on the right when on the engine.

[nevhunter]

IF you want trouble from an Ariel single, fit a bigger oil pump. They make less power , run hotter and leak oil. The scavenge set up is not the world's best. Oil only goes right to the bottom when the motor is stopped. A side valve barrell expands very unevenly no matter who makes it caused by the exhaust port location and it will have generally poorer ring sealing as a consequence .Nev