Static flow through oil pump

[barrydevon]

Long story short, I bought a long stroke A7 plunger. Oil mysteriously disappeared and it went bang. (Oil system seemed to work properly with flow back to tank prior to this).Expensive rebuild later and I have just put the oil pump on. Put a little oil in tank to check for leaky junctions etc (with timing case off), and next day noted the oil flowed out over the top of the pump body. Does this mean pump is not stopping the oil and it will wet sump instantly if tank filled or will the flow stop when enough is sat in the various ports and chambers in the engine. My first A7 so just don't know the quirks. Any advice/ guidance other than "get the short stroke, parts are cheaper and easier to find"?

[limeyrob]

A very interesting question that's been bothering me too.  A few months back I rebuilt my A10 SA engine and spent some time seating the wet-sump valve seat/ball/spring and was confident that the bike would not wet sump.  I refitted the old oil pump but stripped and lapped the faces so I was fairly sure about that too.  When parked the bike will put a jam jar of oil in the sump in 2 weeks.  I'm now thinking its running though the pump which begs the question "how is the oil pressure?".  I have a spare oil pressure relief valve and I'm considering drilling and tapping the spare for a gauge.
I took the timing cover off to do the timing after it had been standing a few weeks.  A lot of oil was in the timing chest witch suggests that it is running though the pump not the wet sump valve.   The problem is that if the pump is peeing oil out it will still look good on the oil return but it will be by-passing the crank.

[muskrat]

G'day Barry 
Sounds to me like the pump body is distorted or the gasket isn't sealing. Pull the pump off and lap the base with wet&dry on glass. Use a new gasket (the ones from SRM are best) making sure the bit under the "nose" is the same thickness.
Cheers.
Now get over to Introductions and give us your story.

G'day Rob.
There will always be oil in the timing case till it reaches the hole into the crankcase.
Cheers

[Beeza]

I noticed on one of my rebuilds that oil was passing over the pump too, on close inspection of the gasket supplied, it was a loose fit, that one of gasket holes slightly overlapped from the oil supply hole to the bolt hole, allowing oil to leak out through the bolt spring washer. The newer SRM gaskets seem to fit better.
Thomas

[JulianS]

There are some dreadful pump gaskets on the market.

Photo shows SRM gasket on the left which fits perfectly, genuine BSA top right which fits perfectly when a thin fibre or gasket paper washer is used on the pump nose and bottom right nasty poor quality horror which could seize your bike.

The oil holes in it are too small and the mounting holes are too large allowing the gasket to move and mask the oil holes in the pump and crankcase. These oversize mounting holes are needed for the unit singles where the pump body was dowelled to the crankcase, but the oil holes still too small.

[muskrat]

G'day Garry.
Note Julians pic of the SRM gasket has the feed hole larger than the other 3. It's for the "A65 type" where the non-return ball sits against the pump. No problem fitting on our A7 & A10 motors. I recommend getting one.
Cheers

[limeyrob]

This morning's task? Order the SRM gasket - well 2 since I'm bound to mess one up

[chaterlea25]

Hi All,
I don't know if the long stroke pump is different to the later pumps or not?
If the same refer to the recent topic on buying a new pump or not.

Old mazac pump bodies are well worn at this stage and often porus as well
Not worth the risk in re using them in my opinion

John

[limeyrob]

Just ordered the SRM gasket, I'll start with that.  Of course I realized I'd not got the correct spanner so I've just got a 25/32 off e-bay.  It didn't matter before but now I know they exist I had to have one