Date: Wed, 26 Aug 1998 10:05:00 -0500
From: Colin Sharpe
John Magyar wrote:
> I believe that another likely (or perhaps the likely) source of wet
sumping is
> the oil pump. The oil feeds through the oil pump and then to
the anti drain
> valve in the timing cover. I still get wet sumping. This
wet sumping is
> after several rebuilds and gasket replacements (this is a race
bike). I have
> done nothing to the oil pump so I believe that leakage past the oil
pump shaft
> is the most likely source of wet sumping in my situation. All
this said, I
> would recommend the later model timing cover if you have one handy.
Keep in
> mind that there is a different (thicker I believe) rubber doughnut
washer and
> maybe a special backing shim that should be used with this later
model cover.
>
> Regards,
>
> John Magyar
At risk of being told " It doesn't work / you risk seizing your engine" by other posters (Again!), I will repeat. It should not be the shafts that cause the leak, but it may well be the side play on the gears themselves. This can be taken out by rubbing the body on a sheet of abrasive paper supported on glass.
I have tried this, and it worked for me. I also read about this cure, I think in a Norton service release, if not it was something from a club for Norton owners. I also know other people who say it worked. Someone who posted here warned "Been there, done that, it doesn't work", and also warned that messing with the oil pump increased the chances of engine disaster.
Do what you think is best.
English.
Date: Wed, 26 Aug 1998 14:55:49 -0400
From: Pete Serrino
Wet sumping aside a case might be made for periodic gear lapping just to maintain proper oil pressure.
Recently a local Norton owner installed an oil pressure gage on his Commando only to find readings were 40PSI cold and 8-10 hot. Shimming the relief valve did not improve things but careful lapping brought the pressure up to 65PSI cold and 35-40PSI hot.
Cheers,
Pete Serrino
Date: Thu, 27 Aug 1998 09:29:35 EDT
From: John Magyar
In a message dated 98-08-26 20:08:05 EDT, John Magyar wrote:
> Excellent point. Tend to agree that this could be the primary
culprit and
> that the shafts (the shaft to the pinion gear and the shaft between
the
> pressure and scavenge pump gears) are only the conduits. The
main point to be
> made for the benefit of the readers is that the wet sumping remedy
of the later
> model MkIII timing cover is not necessarily going to be effective
>
> I have lapped the pump and plate surfaces as you described with an
earlier
> Norton in an earlier life and found no ill effect whatsoever.
I paid special
> attention to the clearances during the gradual lapping process.
Then, someone else wrote:
>To tell the truth its been so long since that engine was rebuilt with
the MkIII
>timing cover that I've totally forgotten why or where I heard of the
idea in
>the first place. I think at the time the guy rebuilding the engine
thought I
>had brought up an interesting idea and wanting to try it. Was the
MkIII timing
>cover redesign intended to prevent wet sumping in the first place
or was there
>another reason? And I've forgotten what the access plug in the timing
cover is
>for. Checking timing chain tension?
The access plug was to check slack in the cam chain. One still has to remove the timing cover to adjust this chain.
There were several aspects of the "redesign" of the MkIII. In the MkIII timing cover, there is a small spring loaded valve that presses up and seals against the pump output washer (rubber) when the engine shuts down and oil pressure drops. This is supposed to keep oil from draining down from the oil tank and out of the big end journals. This valve is located in the oil feed circuit between the oil pump and journals, thus oil drain back through the clearances within the pump are not stopped by this valve.
Assuming the MkIII spring loaded valve and pump gaskets are functioning
properly, the oil pump clearances are probably what are causing the wet
sumping. At least in my case, that is likely what is happening.
Then, Dave Friesen wrote:
>My problem with wet sumping was more that a "minor inconvenience"
as draining
>the oil was not a cherished task, especially back in the NW when riding
days
>where held quite dear.
You may want to remove the timing cover, inspect and perhaps lap the
pump as described elsewhere, inspect the check valve and spring, and replace
the pump gaskets. As good practice, I would also replace the timing
cover gaskets and cam seal.
Barring something like a fractured component bleeding oil, the above steps should alleviate your wet sumping problem.
Regards and good luck,
John Magyar
AHRMA #221
Dances with Wheels
Dances with Alloy
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