OIL NON-RETURN VALVE

Hal

Hal

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I run a Norton specialty shop in Japan.I would greatly appreciate your advice.

I built a Commando MKIII race bike.
Unfortunately, the connecting rod bearings melted almost immediately, and I'm investigating the cause.

While reviewing the Andover Norton parts list, I noticed one thing: I hadn't installed a part labeled “OIL NON-RETURN VALVE.”
andover-norton.co.uk

Andover Norton - PLUNGER-OIL NON-RETURN VALVE - 06.6199

PLUNGER-OIL NON-RETURN VALVE
andover-norton.co.uk

Engines prior to the MKIII didn't have such a part, so I assembled the MKIII engine without knowing this.

I don't think this is the cause, but does anyone know what function this OIL NON-RETURN VALVE serves?
 
Hal said:
I run a Norton specialty shop in Japan.I would greatly appreciate your advice.

I built a Commando MKIII race bike.
Unfortunately, the connecting rod bearings melted almost immediately, and I'm investigating the cause.

While reviewing the Andover Norton parts list, I noticed one thing: I hadn't installed a part labeled “OIL NON-RETURN VALVE.”
andover-norton.co.uk

Andover Norton - PLUNGER-OIL NON-RETURN VALVE - 06.6199

PLUNGER-OIL NON-RETURN VALVE
andover-norton.co.uk

Engines prior to the MKIII didn't have such a part, so I assembled the MKIII engine without knowing this.

I don't think this is the cause, but does anyone know what function this OIL NON-RETURN VALVE serves?
Click to expand...
It prevents the engine from wet sumping. When after not using the bike for a while, the oil tank drains oil into the base of the engine and the oil tank can completely empty, that usually takes a few weeks or more.

Did you prime the engine and fill the crank with oil before starting it? Do you have an oil pressure gauge on the bike? Where the oil hoses hooked up properly.
 
Hal said:
I run a Norton specialty shop in Japan.I would greatly appreciate your advice.

I built a Commando MKIII race bike.
Unfortunately, the connecting rod bearings melted almost immediately, and I'm investigating the cause.

While reviewing the Andover Norton parts list, I noticed one thing: I hadn't installed a part labeled “OIL NON-RETURN VALVE.”
andover-norton.co.uk

Andover Norton - PLUNGER-OIL NON-RETURN VALVE - 06.6199

PLUNGER-OIL NON-RETURN VALVE
andover-norton.co.uk

Engines prior to the MKIII didn't have such a part, so I assembled the MKIII engine without knowing this.

I don't think this is the cause, but does anyone know what function this OIL NON-RETURN VALVE serves?
Click to expand...
Prevents (or attempts to) wet sumping. The MK3 also has a different rubber seal from the oil pump to timing cover. That missing or wrong can easily starve the engine of oil.
 
marshg246 said:
Prevents (or attempts to) wet sumping. The MK3 also has a different rubber seal from the oil pump to timing cover. That missing or wrong can easily starve the engine of oil.
Click to expand...
Omitting that plunger shouldn't affect anything to your big ends. But as Greg states - the oil seal for a MK3 is different than all other years, and using the wrong seal with a MK3 timing cover would cause a huge loss of oil pressure, which would cause rapid big end failure.
 
Thanks for all the advice, everyone.

It seems unlikely that forgetting to install the OIL NON-RETURN VALVE is the problem.

I don't remember which model's oil seal I installed, but checking, I see I used the one in the photo. Comparing it to the Andover one, it probably looks like it's for the MKIII.
andover-norton.co.uk

Andover Norton - OIL PUMP SEAL Mk3 - 06.6190

OIL PUMP SEAL Mk3
andover-norton.co.uk

The engine is built with parts from JS's Jim. I previously built a 750 engine with the same specs, and that engine has been running fine for years without issues. So I'm investigating whether something related to the MKIII's oil might be the problem.
I ran it on the circuit twice, but the engine noise gradually increased. When I lifted the engine, the big end bearing was severely melted.

I want to install an oil pressure gauge, but I haven't found a good one. I have the type that taps into the head, but I haven't installed it because it's considered unreliable.
 

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Hal said:
Thanks for all the advice, everyone.

It seems unlikely that forgetting to install the OIL NON-RETURN VALVE is the problem.

I don't remember which model's oil seal I installed, but checking, I see I used the one in the photo. Comparing it to the Andover one, it probably looks like it's for the MKIII.
andover-norton.co.uk

Andover Norton - OIL PUMP SEAL Mk3 - 06.6190

OIL PUMP SEAL Mk3
andover-norton.co.uk

The engine is built with parts from JS's Jim. I previously built a 750 engine with the same specs, and that engine has been running fine for years without issues. So I'm investigating whether something related to the MKIII's oil might be the problem.
I ran it on the circuit twice, but the engine noise gradually increased. When I lifted the engine, the big end bearing was severely melted.

I want to install an oil pressure gauge, but I haven't found a good one. I have the type that taps into the head, but I haven't installed it because it's considered unreliable.
Click to expand...
The one in the photo is pre-MK3 and very wrong for a MK3.
 
marshg246

Thanks for the advice.

My understanding is that the left side of the photo shows models prior to MKIII, and the right side shows the MKIII model.
The part attached to my oil pump is the right one, 06.6190.

Am I misunderstanding something?
 

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Hal said:
marshg246

Thanks for the advice.

My understanding is that the left side of the photo shows models prior to MKIII, and the right side shows the MKIII model.
The part attached to my oil pump is the right one, 06.6190.

Am I misunderstanding something?
Click to expand...
Yes, you have the left side installed - not the right side. Easy to tell because the flat metal area on the pump is much bigger on the MK3 and the correct seal covers that area - yours covers about 1/2.
 
marshg246 said:
Yes, you have the left side installed - not the right side. Easy to tell because the flat metal area on the pump is much bigger on the MK3 and the correct seal covers that area - yours covers about 1/2.
Click to expand...
The original photo may have been difficult to see clearly.

The seal attached to the oil pump is the one in the photo.
This appears to be the correct one for the MKIII, part number 06.6190.
 

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Hal said:
The original photo may have been difficult to see clearly.

The seal attached to the oil pump is the one in the photo.
This appears to be the correct one for the MKIII, part number 06.6190.
Click to expand...
Whatever you say. But notice that the latest picture has a rusty oil pump bush and is the same diameter as the seal and the other has no rust and the seal is 1/2 the diameter of the oil pump bush and you can see the outline of where there once was a correct seal. So, IMHO, two different pumps - which came from the bike?
 
marshg246 said:
Whatever you say. But notice that the latest picture has a rusty oil pump bush and is the same diameter as the seal and the other has no rust and the seal is 1/2 the diameter of the oil pump bush and you can see the outline of where there once was a correct seal. So, IMHO, two different pumps - which came from the bike?
Click to expand...
Thank you so much.

Both oil pumps are the same ones removed from the MKIII.

The photo might be a bit hard to see.
 
That rusty oil seal seating makes me question the integrity of the pump …?

Do you have any kind of anti wet sump device in the oil line between the tank and the engine ?
 
Fast Eddie said:
That rusty oil seal seating makes me question the integrity of the pump …?

Do you have any kind of anti wet sump device in the oil line between the tank and the engine ?
Click to expand...
Eddie, thanks for the advice.

I've installed a cock on the oil line.

I disassembled, cleaned, and reassembled the oil pump, but I'm still concerned, so I ordered a new one from Andover.
I also disassembled and cleaned the Pressure Release Valve, but it's not moving smoothly, so I plan to replace that with a new one too.
 

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Well, I realise no one will admit it… but the possibility that that valve was off, or partially off, even accidentally, is not something you can 100% rule out.

I would never have something like that on a track bike, there is simply too much going on when preparing and riding a bike on the track to make an error more likely, for me at least. And riding at track speeds means an increased likelihood of assured destruction if switched off by accident.
 
Last edited:
It may have been opened ie lever in line with pipe but did anyone check that the tap worked and what the lever did in what position. Best left off, there is no place for a non return valve in a race bike, if you are worried about wet sumping drain the oil after the meeting and fill before it leaves the garage.
 
marshg246 said:
Whatever you say. But notice that the latest picture has a rusty oil pump bush and is the same diameter as the seal and the other has no rust and the seal is 1/2 the diameter of the oil pump bush and you can see the outline of where there once was a correct seal. So, IMHO, two different pumps - which came from the bike?
Click to expand...
Hi Greg, I think that photo was taken with the flash on, so the reflection on the oily surface of the rubber has made it look silver.
 
Thank you all for your advice.

It's helpful to know that the oil seal and oil non-return valve don't seem to be the problem.

I'll investigate further to see if there might be an issue with the oil pump or pressure release valve.
 

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