Oil Pressure Issue

71 Commando. 13k miles. It sat for about 15 years. It had always wet sumped and I wanted to fix that while going through the items in the timing cover. So I replaced: Oil pump, oil pump gasket, conical seal, crank seal, timing seal, bypass piston, cap, and spring. I also fitted the oil filter kit and the HNW oil pressure gauge. Filled with 20-50 Royal Purple HPS. Shimmed bypass to give 65ish psi on cold start.

It still wet sumped while sitting. So I added the HNW anti wet sump valve/banjo bolt. That cured the wet sumping.

I finally got to take the bike for a test ride. First short ride (3 miles) all was good. Second ride (3 miles), the oil pressure dropped to zero or near zero at idle and didn't maintain the 10/1000 ratio when free reved to 3-4k. It was close, but still down at about 35 @ 4k.

I know many will say that the gauge is a distraction. I have not been able to verify the flow back to the tank. I will do that ASAP.

Things I've checked: verified that all rocker shaft oiling holes are pointed outward from the head (toward the valves). Verified crank seal was in properly (garter in) and intact. Pulled the oil pump to verify that that the gasket was in the right way round. It was, but see the attached pics for weird witness marks on it. Could it have been leaking at the edge?

Thanks for the help!!

-Kyle

Oil Pump face witness marks:
https://www.amazon.com/photos/shared/OvlTBTThSb6re3sfZs9H3Q.etoZXeultxpuuQp9qB7uoK

Oil pump gasket witness marks:
https://www.amazon.com/photos/shared/CkB62DGkRNKkl4XvksBgRg.QoWkJ3VtT1s390eEnZr-WQ

First thing I would do is remove the anti wet-sump valve. Check the oil pressure at idle without valve after a spirited run.

I've never shimmed up an oil pressure release valve. They seem to work just fine.

Thanks Jim. That is the plan. Wondering if missed anything and if that odd witness mark at the edge of the oil pump gasket was an issue.

-Kyle

What rpm is it idling at when pressure seems too low? Can you verify gauge accuracy someway?
My 74 850 will do a little under the 10 psi per 1K rpm rule of thumb and have seen less than 10 psi while idling in traffic in heat. Gauge scale isn't good below that point.

Not familiar with HNW anti wet sump valve. Is it the spring loaded automatic type know to fail or not let oil through at startup for 15+ minutes because of poor suction from the pump?

disquek said:

Things I've checked: verified that all rocker shaft oiling holes are pointed outward from the head (toward the valves).

Click to expand...

Unless I'm missed something in the threads about the oil holes they should be pointing inward??

Their orientation shouldn't be causing pressure issues; excessive big end clearance or a restriction in the pressure galleys is more likely. If your lower end is original the bearing inserts have holes that align with holes in the rods that were intended to squirt oil at the wrist pins/pistons to lubricate/cool respectively. Excessive big end clearance coupled with this vestigial oiling strategy could be the root cause, but do wait for the heavy hitters to weigh in before tearing your engine down.

Best

RoadScholar: https://www.oldbritts.com/11_head_info.html

Here are the pics of the weird witness marks on that gasket and the pump so you can see them more easily.

Not sure shimming for a cold oil pressure is the right way to go, a hot oil setting would be the way I would go given a choice. In his engine rebuild DVD I think Mick Hemmings just set the valve by changing shims until by shaking the valve you could hear the piston rattling inside, will try and have a look.

When you say it wet sumps, over what period?

Also as others say, be very wary of any so-called automatic anti wet sump valve in the oil feed line. Personally I'd never use one and would rather have a wet sump than a destroyed engine.

Ian

Worth a read

https://www.accessnorton.com/NortonCommando/oil-pressure-relief-valve-shims-2008.2187/

When I was at Mick Hemmings shop last year, he said that he added shims until the free play in the spring was not quite all taken up. In other words, it will still just "rattle" in the housing when shaken. Unscientific, but this is what he advised. The pressure release valve on mine had no shims in it either, but using the above method, I think I put one shim in.

I have the identical set up to you. I installed pressure gauge to confirm HNW valve is working on start up. I took shims out to get about the same as you on start up. When engine is hot I get around 35psi as a maximum and am happy with that. The pressure drops off on idle when hot to around 10psi. I have used Castrol classic and Royal purple and both seem to work better than other oils in that I get a more consistent pressure when the engine is hot. I have an Atlas with the same set up- new Andover pump, HNW valve, spin on filter, and gauge using Castrol classic. The pressure on this is much lower, about 20psi, when hot, but plenty of oil on the return. General consensus on this forum is that low pressure is not a problem with these engines as long as the return flow is good. Both engines have been rebuilt with cranks and rebores supervised by Norman White.

RoadScholar said:

Unless I'm missed something in the threads about the oil holes they should be pointing inward??

Click to expand...

No.

As you said yourself.....
https://www.accessnorton.com/NortonCommando/head-and-rocker-spindles.7507/

kommando said:

Not sure shimming for a cold oil pressure is the right way to go, a hot oil setting would be the way I would go given a choice.

Click to expand...

Shimming the OPRV with cold oil is the only way to do it properly because the OPRV tops off the high pressure when the oil is cold/thick. When the oil is hot/operating temperature the OPRV doesn’t work anymore (unless the oil pressure would still be above the pre set value, which isn't likely). Recommended OPRV shimming is 60 to 70 psi max (with cold oil of course), hot/operating temperature should read at least 30 psi at 3000 rpm (guideline expect about 10 psi per 1000 rpm at operating temperature).

Kyle, I read you already checked some points however lack of oil pressure can be caused by all associated parts of the oil pressure system like for instance oil pump housing, gears and shafts (side play of the gears will cause severe oil pressure drop), rockers/shafts, big-end shells etc. It will take some experimenting to find the cause, take one step at the time. As JimC suggested do also replace our HNW oil tank anti wet sump valve for the original filter bold. I would be very surprised to learn our oil tank AWSV is causing your oil pressure drop as our valve is known not to affect the oil pressure at all unlike certain other inline valves. HNW has been distributing this oil tank AWSV for many years now and truly never ever experienced any problems from our customers. This valve is also used on my Commando for many years and countless miles in extreme hot and cold temperatures without problems (of course I notice some oil pressure drop on my permanently fitted oil pressure gauge in extreme hot temperatures).

Hopefully you get your oil pressure problem sorted out and in the unlikely event our AWSV did cause your oil pressure drop please return the AWSV for investigation and you will get a full refund.

Constant Trossèl
www.hollandnortonworks.eu

kommando said:

Not sure shimming for a cold oil pressure is the right way to go, a hot oil setting would be the way I would go given a choice. In his engine rebuild DVD I think Mick Hemmings just set the valve by changing shims until by shaking the valve you could hear the piston rattling inside, will try and have a look.

Click to expand...

Excessive pressure with cold oil is exactly why the OPR valve is needed. No need to worry about too high pressure with hot oil. Also, shimming will not increase pump pressure, only limit it.

disquek said:

71 Commando. 13k miles. It sat for about 15 years. It had always wet sumped and I wanted to fix that while going through the items in the timing cover. So I replaced: Oil pump, oil pump gasket, conical seal, crank seal, timing seal, bypass piston, cap, and spring. I also fitted the oil filter kit and the HNW oil pressure gauge. Filled with 20-50 Royal Purple HPS. Shimmed bypass to give 65ish psi on cold start.

It still wet sumped while sitting. So I added the HNW anti wet sump valve/banjo bolt. That cured the wet sumping.

I finally got to take the bike for a test ride. First short ride (3 miles) all was good. Second ride (3 miles), the oil pressure dropped to zero or near zero at idle and didn't maintain the 10/1000 ratio when free reved to 3-4k. It was close, but still down at about 35 @ 4k.

I know many will say that the gauge is a distraction. I have not been able to verify the flow back to the tank. I will do that ASAP.

Things I've checked: verified that all rocker shaft oiling holes are pointed outward from the head (toward the valves). Verified crank seal was in properly (garter in) and intact. Pulled the oil pump to verify that that the gasket was in the right way round. It was, but see the attached pics for weird witness marks on it. Could it have been leaking at the edge?

Thanks for the help!!

-Kyle

Oil Pump face witness marks:
https://www.amazon.com/photos/shared/OvlTBTThSb6re3sfZs9H3Q.etoZXeultxpuuQp9qB7uoK

Oil pump gasket witness marks:
https://www.amazon.com/photos/shared/CkB62DGkRNKkl4XvksBgRg.QoWkJ3VtT1s390eEnZr-WQ

Click to expand...

Kyle,
It certainly look as though the gasket hasn't been evenly clamped down. Are the side plates flush with the pump body face?, because if you look closely at the picture you can see vertical lines on the gasket which may indicate that they are not. Personally I would temporarily block all the holes with something (pieces of earplug work well) then work it on a glass plate with grinding paste to be sure it's flat and all three parts are at the same level.

Cheers,

cliffa.

L.A.B. said:

No.

As you said yourself.....
https://www.accessnorton.com/NortonCommando/head-and-rocker-spindles.7507/

Click to expand...

Good catch and a very impressive recall for detail; clearly missed my own post of 10 years ago. Be great if the "fact checkers" in this country had half your ability. Thanks for the sanity check.

Best

RoadScholar said:

Good catch and a very impressive recall for detail; clearly missed my own post of 10 years ago. Be great if the "fact checkers" in this country had half your ability.

Click to expand...

It was really just a lucky search result.