Wet Sumping, Oil Pressure Relief Valve and AMR Modification

Re: Wet Sumping, Oil Pressure Relief Valve and AMR Modificat

swooshdave said:

To jump on this bandwagon I've got a 72 with a MkIII timing cover and it still wet sumps. Maybe a worn pump?

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Although the MkIII cover should reduce the rate of drainage through the pump, it won't prevent oil from seeping along the pump shaft bores from the feed to the scavenge where it can drain straight down to the sump. This is the reason for the pump shaft O-ring modification.

Re: Wet Sumping, Oil Pressure Relief Valve and AMR Modificat

swooshdave said:

To jump on this bandwagon I've got a 72 with a MkIII timing cover and it still wet sumps. Maybe a worn pump?

Click to expand...

Yes, mine does too. As stated, it does help, but not perfect. My pump is reworked and massaged. It is what it is.

Even if it still seeps by, the cam chain inspection hole is still worth it.

Re: Wet Sumping, Oil Pressure Relief Valve and AMR Modificat

swooshdave said:

To jump on this bandwagon I've got a 72 with a MkIII timing cover and it still wet sumps. Maybe a worn pump?

Click to expand...

If you are not happy with the rate your motorcycle is wet sumping it is possible to isolate where the leaks are happening. First you can remove the rocker feed line and just observe how much oil comes out of the oil passageway. If the oil just keeps running out after a period of time then it is safe to assume that your anti wet sump valve is not seating properly. Of course if the oil stops draining there then the anti wet sumping valve is ok. With the Mark III timing cover the oil pressure relief valve has nothing to do with wet sumping.

Unfortunately the 1972 Norton does not have a sump screen which would have been handy by removing and visually checking whether the oil is back flowing through the scavange pump pickup.

Now you can remove the timing cover, plug the oil pump outlet, plug the threaded hole in the engine case and disconnect the oil return hose that goes to the oil filter. Clean the pump and the area all around really well. Over a period of time visually inspect to see where the oil is leaking externally. If it is leaking at the brass end plate seam, resurfacing the plate and the pump body should really help. If it continually leaks out through the oil pump's input shaft that would indicate there is an internal leakage of the pump from the delivery side to the scavange side. This is what the AMR o-ring modification corrects. Also if there is a leak around the area where the oil pump is mounted on the engine case it could mean that the gasket is shot or the mounting nuts/studs are loose. When I took my bike apart the mounting nuts were barely snug and the studs were loose in the engine case.

These are ways of methodically isolating the cause of rapid wet sumping on your engine. I hope this is of some help.

Peter Joe

Re: Wet Sumping, Oil Pressure Relief Valve and AMR modificat

PeterJoe said:

AMR modified oil pump body with counter bored shaft holes and the O-Rings.

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Is an o-ring the best solution for this application? Wouldn't an actual oil seal be better?

Re: Wet Sumping, Oil Pressure Relief Valve and AMR modificat

yes IMHO a seal IS the proper way to seal a rotating shaft vs an O ring but it will work for a while. an O ring is more apt to be used on a stationary app or where two parts slide across each other like a short travel piston is pushed in and out in a bore (think automatic transmission's). also the MKIII timing cover has a habit of the piston sticking in the open position so just give it more clearance in the bore.

swooshdave said:

PeterJoe said:

AMR modified oil pump body with counter bored shaft holes and the O-Rings.

Click to expand...

Is an o-ring the best solution for this application? Wouldn't an actual oil seal be better?

Click to expand...

Re: Wet Sumping, Oil Pressure Relief Valve and AMR modificat

bill said:

Is an o-ring the best solution for this application? Wouldn't an actual oil seal be better?

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Only if you wanted it to last.
Unfortunately not much room to work with. Jim