AMR Nortec Mod

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I feel a whole lot smarter but I know it will only last a little while. It doesn't take long to find something to humble my thought processes.
 
Me too guys. Been stuck on this all day.
Maybe I can get some work done now................
 
MichaelB said:
Ahhh, Ok. I see that now.
I thought it was blowing off into the CC, crankcase.
So, the pressurized oil is blowing off into the feed of the pressure causing item, the pump.
Doesn't seem very efficient.

That appears to be a GOOD reason to reroute it.
Not so sure about the wet sumping as it just drips back into the pump on the original dump.
Click to expand...

Not quite, when the PR piston is overcome and bleeds oil pressure it goes to the Non pressure or feed side of the oil pump (basically into the rubber hose route of the oil (tank) to oil pump.

All this mod does is remove another possible wet sump route that could bypass their check ball mod.
 
I get that. It's feeding right back into the pump, not to the sump.
It can go around and around.
Doesn't get to the sump till the crank.
How does it affect wet sumping?
 
MichaelB said:
I get that. It's feeding right back into the pump, not to the sump.
It can go around and around.
Doesn't get to the sump till the crank.
How does it affect wet sumping?
Click to expand...
Let’s say oil is seeping around your OPRV piston which is plausible. Currently that leaked oil is going back into the oil pump, through the crank and into the sump.

With the mod the oil now has to leak past the OPRV and up and into the timing case. It needs to fill up the timing case and then into the crankcase. I see it more of a delaying tactic than anything else.

But if the ball check and oil pump don’t leak then it’s redundant. I have a feeling there’s no way to ever get an oil tight oil pump. It’s just not possible with a gear oil pump, there is always some clearance there.

So we do whatever we can to slow the flow.
 
grandpaul said:
So you are saying that in a STATIC state, you had oil leakage past the stationary oil pump end plate from the oil pump body? That's pretty knackered!
Click to expand...
There is a another place you can also check.
I have foudthe cast iron plate on the oil pump sometimes sticks proud of the oil pump body, this prevents the pump from fitting flush to the crankcase. It's a simple mto carefully file away this plate on one side where it sticks up, allowing the pump to fit flush.
Also, leave timing cover off, with oil tank 3/4 full a nd see how long it takes oil to fill up a container, sometimes there is a broken oil return pipe inside the oil tank that you cannot see.
Both would cause rapid wet sumping.
 
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swooshdave said:
Let’s say oil is seeping around your OPRV piston which is plausible. Currently that leaked oil is going back into the oil pump, through the crank and into the sump.

With the mod the oil now has to leak past the OPRV and up and into the timing case. It needs to fill up the timing case and then into the crankcase. I see it more of a delaying tactic than anything else.

But if the ball check and oil pump don’t leak then it’s redundant. I have a feeling there’s no way to ever get an oil tight oil pump. It’s just not possible with a gear oil pump, there is always some clearance there.

So we do whatever we can to slow the flow.
Click to expand...
I don’t think that’s quite right Swoosh...

I think the issue is that when the OPRV outlet routes back into the pump feed, what can happen when the engine is NOT running is that oil from the tank flows BACKWARDS into the OPRV, on to the (leaky) pump and then into the sump, thus effectively providing oil in the tank with a means of by-passing the AMR ball valve mod completely. This will result in a more slow wet sump process, but still a wet sump process!

When the OPRV outlet is routed into the timing case, oil cannot flow as described above. In this case the only way oil can flow from the tank and into the engine is via the AMR ball valve.

At least that’s my understanding, and I’d be very happy if someone can either confirm or correct me...?
 
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Bernhard said:
sometimes there is a broken oil return pipe inside the oil tank that you cannot see.
Click to expand...

Not the majority of Commandos with the triangular-shaped side oil tank (so not early Fastback and central oil tank models) as the Commando's rigid return pipe does not rise through the contents of the oil tank but is mainly external so the oil cannot drain to the crankcase due to a broken return pipe.

swooshdave said:
Let’s say oil is seeping around your OPRV piston which is plausible. Currently that leaked oil is going back into the oil pump, through the crank and into the sump.
Click to expand...

For the standard pre-Mk3 Commando, leakage through the OPRV passes into the timing cover crank feed gallery, it doesn't "go back into the oil pump". Oil can also leak through the pump as well as the OPRV so that's two potential points of leakage into the timing cover gallery.
 
Ok, I think I have I have now. I guess I have to see the word BACKWARDS 3 or 4 times to get it.
In static mode, the head pressure from the bag feeds through the dump backwards into the OPVR backwards, into the channel
that feeds the crank on the way to the sump.
 
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Curious how many folks use same as my procedure?
1. remove oil pump drive gear to properly get straight access to the 4 pump screws?
2. run a 2BA tap through the brass plate and die over the 2 BA screws?
3. light surface polish of brass plate if needed AND iron body (feed and scavenge) if needed to remove excess clearance from gear.
4. use lite wicking loctite on screws after reassembly?

Back to "other unintended oil flow paths"...
 
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MichaelB said:
Ok, I think I have I have now. I guess I have to see the word BACKWARDS 3 or 4 times to get it.
In static mode, the head pressure from the bag feeds through the dump backwards into the OPVR backwards, into the channel
that feeds the crank on the way to the sump.
Click to expand...
Isn't that what I said?
 
swooshdave said:
Isn't that what I said?
Click to expand...
According to this you have routing back through the pump, unless I'm reading it wrong..

swooshdave said:
Let’s say oil is seeping around your OPRV piston which is plausible. Currently that leaked oil is going back into the oil pump, through the crank and into the sump.

With the mod the oil now has to leak past the OPRV and up and into the timing case. It needs to fill up the timing case and then into the crankcase. I see it more of a delaying tactic than anything else.

But if the ball check and oil pump don’t leak then it’s redundant. I have a feeling there’s no way to ever get an oil tight oil pump. It’s just not possible with a gear oil pump, there is always some clearance there.

So we do whatever we can to slow the flow.
Click to expand...
You have it seeping back into the pump.
That's not the issue.

In static mode, it's backfeeding into the OPRV, then dropping into the galley/channel, then flows by the oil pump on the back side of the new installed spring/ball
into the crank onto the sump.

It's going around the pump., backwards.,.....
 
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MichaelB said:
According to this you have routing back through the pump, unless I'm reading it wrong..


You have it seeping back into the pump.
That's not the issue.

In static mode, it's backfeeding into the OPRV, then dropping into the galley/channel, then flows by the oil pump on the back side of the new installed spring/ball
into the crank onto the sump.

It's going around the pump., backwards.,.....
Click to expand...
Ah, yes. Thanks. I thought that going into the OPRV would cause it to head back into the return which feeds the oil pump. But I was even questioning how it could do that.

What would be really cool is to get an x-ray of a timing cover. Anyone have access to one?
 
I wouldn't have thought anyone would have the Nortech OPRV modification done without having the anti-drain valve modification done?

swooshdave said:
What would be really cool is to get an x-ray of a timing cover. Anyone have access to one?
Click to expand...


Hopefully, diagrams might make it clearer.

Pre-Mk3 Commando

Engine running and OPRV operating
Oil vented from the OPRV returns to the pump feed through the timing cover and crankcase return gallery...
AMR Nortec Mod


Engine static
..Not only can oil leak through the pump into the timing cover oil gallery but can potentially flow in the opposite direction through, or along the thread of, the OPRV.
AMR Nortec Mod


Mk3 (or modified pre-Mk3) timing cover engine running and OPRV operating
The Mk3 timing cover drilling between the OPRV and the return gallery in the crankcase is blanked-off (or gallery is plugged = AMR) so oil from the OPRV vents into the timing chest and the Mk3 anti-drain plunger or AMR ball-valve conversion is held open by pump pressure...
AMR Nortec Mod


...therefore the potential for the oil to flow 'backwards' through the drilling and OPRV when the engine isn't running is removed and the anti-drain valve closes to prevent leakage through the pump to the timing cover gallery, however, oil can still leak along the pump shaft unless the AMR shaft seal mod. is done and also leak from the pump joints, or pump to crankcase joint faces mentioned previously.
AMR Nortec Mod
 
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