New Commando owner with bad sumping problem

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storm42 said:
What would happen if the pressure release valve was stuck open a bit?
Click to expand...
It's a MK3 timing cover so the release valve doesn't connect to the oilway drilling in the crankcase (as it would with a pre-Mk3 cover) so there no possibility for the feed oil to flow in the reverse direction through a stuck valve and bypass the oil pump. The only way oil can reach the OPRV in a MK3 timing cover is through the pump (and past the anti-drain valve plunger assuming it's fitted?).

Edit: Unfortunately, Tom P hasn't mentioned if the Mk3 cover anti-drain valve is fitted or not or if it has the Mk3 06.6190 pump seal and 06.6191 pump feed bush which is significant as the anti-drain valve would certainly prevent oil from draining through the pump in "minutes" if it is there.
 
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MexicoMike said:
Sounds like it was a simple oversight - not tightening the endplate cover bolts! Who hasn't done something similar? :rolleyes:I know a professional mechanic on a famous drag-racing team who once left a shop towel in the engine during a "refresh" between rounds with unhappy consequences! Surprisingly, he still had a job afterwards! ;) (The advantage of having several championship seasons to offset that one "Aw, ship!" :eek: event) :)
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No he's saying the end plate was proud of the gasket sealing face
Not end plate bolts being loose
Cheers
 
I'm not understanding how the end plate can NOT be sealing against the face if the bolts are tight. But it's been a while since I had a Norton pump out so maybe I'm missing/forgetting something... :(
 
MexicoMike said:
I'm not understanding how the end plate can NOT be sealing against the face if the bolts are tight. But it's been a while since I had a Norton pump out so maybe I'm missing/forgetting something... :(
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If there is enough slack in the holes then the endplate can seat but also be cocked to one side enough so that it stops the pump seating against the crankcase. So the bolts were tight but the endplate was out of position.

It also means the pump had access to air not oil alone on the feedside, so possibly aerated oil was being fed to the big ends. So worth getting the oil pressure checked or listening out for worn big ends.
 
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L.A.B. said:
Edit: Unfortunately, Tom P hasn't mentioned if the Mk3 cover anti-drain valve is fitted or not or if it has the Mk3 06.6190 pump seal and 06.6191 pump feed bush which is significant as the anti-drain valve would certainly prevent oil from draining through the pump in "minutes" if it is there.
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Sorry L.A.B. I should have mentioned, It does have the non return valve in the timing cover as well as the 06.6190 pump seal and 06.6191 pump feed bush (though i'm glad you bough it up because I was unaware of the difference between the 06.9911 and 06.6191)
There's certainly lots to learn, especially when the engine is a Frankenstein mixture of modifications and upgrades!
Tom
 
kommando said:
If there is enough slack in the holes then the endplate can seat but also be cocked to one side enough so that it stops the pump seating against the crankcase. So the bolts were tight but the endplate was out of position.

It also means the pump had access to air not oil alone on the feedside, so possibly aerated oil was being fed to the big ends. So worth getting the oil pressure checked or listening out for worn big ends.
Click to expand...
Luckily I noticed that oil was somehow getting to the sump before I got around to re-assembling the Boyer rotor/stator so it never ran in that condition.
Tom
 
Tom P said:
It does have the non return valve in the timing cover as well as the 06.6190 pump seal and 06.6191 pump feed bush
Click to expand...

Thanks for the update as the presence of the anti-drain valve (assuming the plunger isn't stuck open) bush and seal virtually eliminates the possibility of oil draining through the pump feed gears as the cause of the problem although oil can still drain from the feed side to the scavenge side of the pump along the shaft clearance, the anti-drain valve should reduce the rate of tank drainage to several days or longer.
 
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Tom P said:
Well, progress has been made. I removed the oil pump and noticed that the cast iron endplate was very slightly proud of the sealing face so it was not allowing the pump to seal on the gasket. So far it looks good, but I will be interested to see how much oil has sumped by tomorrow morning.
Thanks for all your ideas and help
Tom
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Been there, done that. Discovered the problem before reassembly so no damage. Glad to hear you also found out before running the motor.
 
What about those 750 and 850 Mk2 Norton owners out there who are bringing their pistons up to TDC before parking in an effort to slow down wet sumping? Is this just an opinion or does it actually work? Has anyone measured or compared the difference?
 
jseng1 said:
What about those 750 and 850 Mk2 Norton owners out there who are bringing their pistons up to TDC before parking in an effort to slow down wet sumping? Is this just an opinion or does it actually work? Has anyone measured or compared the difference?
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I can’t tell you how much difference it makes on my 72 750 Combat as fortunately it doesn’t wet sump much .
It does make a difference in my 1950 ES 2 though . It slows it down but doesn’t stop it . The pump was lapped when I rebuilt it and I don’t ride it much since I finished up the Commando ( the newest toys get all the attention for a while) so it has lots of time to wet sump and it does . I always drain the crankcase and return the oil to the tank before starting but of late I find it easier to simply drain the oil tank after a ride into a Morris oil jug I keep for that purpose. Before draining the tank I hang a placard on the steering damper knob reading “ FILL OIL BEFORE STARTING “
 
jseng1 said:
What about those 750 and 850 Mk2 Norton owners out there who are bringing their pistons up to TDC before parking in an effort to slow down wet sumping? Is this just an opinion or does it actually work? Has anyone measured or compared the difference?
Click to expand...
My bike is a 74' Mk. II.
I roll the pistons up to TDC after shutdown.
I do use that setting/positioning after reading of the TDC setting, wet sumping issues on various years of Commandos on this site. I pay fairly close attention to it.

I just checked two days ago after not riding for 3+ weeks because of weather.
I keep my oil tank filled to the low mark on the dipstick. I pulled the drain plug from the bottom of the engine and didn't need to...maybe two ounces came out.

I have also taken a hard look at oil volume in the crankcase after an engine shutdown without setting the pistons at TDC.
I checked after it sat for 12 days (fishing trip) and drained just under 16 ounces or almost 2 cups from the crankcase.
I understand the concept of positioning the crank/pistons at TDC to block passage/flow but I have never ventured any deeper than my original inspection and clean up of the oil pump during restoration.
I have also read from other members that the TDC positioning had zero bearing on their wet sumping issues.
 
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Richard Tool said:
I can’t tell you how much difference it makes on my 72 750 Combat as fortunately it doesn’t wet sump much .
It does make a difference in my 1950 ES 2 though . It slows it down but doesn’t stop it . The pump was lapped when I rebuilt it and I don’t ride it much since I finished up the Commando ( the newest toys get all the attention for a while) so it has lots of time to wet sump and it does . I always drain the crankcase and return the oil to the tank before starting but of late I find it easier to simply drain the oil tank after a ride into a Morris oil jug I keep for that purpose. Before draining the tank I hang a placard on the steering damper knob reading “ FILL OIL BEFORE STARTING “
Click to expand...

When the oil tank is empty I always put a piece of masking tape on the gas tank and write "oil". I always do that because I nearly make a mistake once.
 
Well close, but no cigar. It took 24 hours to drain most of the tank into the sump (just showing on the dipstick). so I tore her down again and blocked off the unused OPRV hole with a casing screw and topped up the tank. Immediately oil started to trickle out of the oil pump outlet spigot, so it is leaking past the gears. However the MK3 casing with the non return valve should take care of that(if working properly.
I then blocked the oil pump outlet with a length of appropriately sized o-ring rubber, and wiped all visible traced of oil up with a clean kitchen towel. I placed clean drip tray underneath, and so far after about an hour only a single drop has gone into the drip tray (which seemed to come out of the crank shaft) nothing seems to have come from the rear of the pump.

So I can deduce that the non return valve was not sealing on the rubber oil pump seal, so I will replace it and the oil pump gasket and the timing cover gasket.

The one way valve seems to move freely (too freely as it falls out if the case is inverted)

I've attached photos of the timing case (Mk3) and crank case (Combat with modified breather),
Timing cover
Crankcase
 
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If I didn't use reminders and labels I'd still be wondering where it goes or if I filled it...

New Commando owner with bad sumping problem
 
Tom P said:
Well close, but no cigar. It took 24 hours to drain most of the tank into the sump (just showing on the dipstick). so I tore her down again and blocked off the unused OPRV hole with a casing screw and topped up the tank. Immediately oil started to trickle out of the oil pump outlet spigot, so it is leaking past the gears. However the MK3 casing with the non return valve should take care of that(if working properly.
I then blocked the oil pump outlet with a length of appropriately sized o-ring rubber, and wiped all visible traced of oil up with a clean kitchen towel. I placed clean drip tray underneath, and so far after about an hour only a single drop has gone into the drip tray (which seemed to come out of the crank shaft) nothing seems to have come from the rear of the pump.

So I can deduce that the non return valve was not sealing on the rubber oil pump seal, so I will replace it and the oil pump gasket and the timing cover gasket.

The one way valve seems to move freely (too freely as it falls out if the case is inverted)

I've attached photos of the timing case (Mk3) and crank case (Combat with modified breather),
Timing cover
Crankcase
Click to expand...
From what you say it doesn't seem like it does any good to lap the oil pump since oil still leaks past the gear lash. My bike has an oil filter between the oil pump and the tank (requires priming at each oil filter change) but the added resistance of the filter along with parking with the pistons at TDC gives me a couple weeks+ before the oil tank empties. But still there's always some oil in the pump at start up and I've never had a problem from wet sumping. I never drain the sump to start it. I just kick and go. With the hot spark Joe Hunt magneto it always starts with one or two kicks even when when sumped. The one thing I do suggest is adding a 1/16" cross section Oring (1-1/16" ID viton) between the crank PTO seal and the primary sprocket to prevent the seal lip from inverting when wet sumped.
 
Tom P said:
Immediately oil started to trickle out of the oil pump outlet spigot, so it is leaking past the gears. However the MK3 casing with the non return valve should take care of that(if working properly.
Click to expand...

Yes, the anti-drain plunger should be stopping the pump leakage but I wouldn't expect oil to drain so quickly from a newly lapped pump (unless you are filling the tank with 3-in-1 oil? :)).

Tom P said:
So I can deduce that the non return valve was not sealing on the rubber oil pump seal, so I will replace it and the oil pump gasket and the timing cover gasket.

The one way valve seems to move freely (too freely as it falls out if the case is inverted)
Click to expand...
The plunger should move freely and will mostly be pushed out by the spring regardless, although it is only a light spring so perhaps a new spring is needed?
 
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L.A.B. said:
Yes, the anti-drain plunger should be stopping the pump leakage but I wouldn't expect oil to drain so quickly from a newly lapped pump (unless you are filling the tank with 3-in-1 oil? :)).


The plunger should be mostly pushed out by the spring regardless, although it is only a light spring.
Click to expand...
Oil is Royal Purple 20w50, and the plunger sits about 80 thou proud of the hole
 
The pump rubber should be slightly compressed between the pump and the timing cover when the cover is fitted.
With the timing cover gasket fitted and the timing cover held in place then the rubber should hold the timing cover about 10 thou from the gasket in the area adjacent to the pump. If not then a shim of suitable thickness can be added behind the rubber (or behind the spigot bush).
 
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