Another! oil pressure question...

ludwig said:

I don't have an oil pressure gauge on my bikes , but check the pressure every other year or so.
Many years ago, coming back from Lagos Portugal ( 6000 km round trip) I checked the pressure, and it was zero at idle.
Revving up , maybe 1 bar max ( 10 -15 psi )
Opening the timing cover, I found the circlip holding the crankshaft seal had popped out .
( only myself to blame..))
Going by the wear marks on the circlip, it must have been out for a long time.
There was NO damage on the engine.
If I had a gauge and watching the pressure drop, it would surely have spoiled the trip.
Instead I had a great trip, without a worry on my mind :



Cabo de San Vincente is the extreme SW tip of Portugal

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I'm with you- after several thousand miles of low to 'zero' @ idle oil pressure with no major issues, I'm about to take it off the bike and call it good enough. All it does is make me look down and go HMM when I should be enjoying flogging the ol' girl through the twisties. At this point if the engine grenades I'm probably halfway to the next rebuild (given the way I ride) anyway...

acotrel said:

I have always believed that oil pressure causes the big end bearings to float and that low oil pressure can allow the bearing metal to pick-up on the steel journal.

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Have you always believed that 60 lbf/sq in through a 1/8” hole in the journal is overcoming the conrod forces and jacking the bearing surface away from the crankshaft?

I think the big end bearing and the journal are kept apart by the presence of an oil film.

I think low oil pressure is a sign that something is wrong, something that may compromise the required continuous presence of the oil film between the journal and the bearing.

"All it does is make me look down and go HMM when I should be enjoying flogging the ol' girl through the twisties."


If that is how a person chooses to use a tool, the tool can not be blamed.
An oil pressure gage provides trending information, which is very useful in the hands of a person who wants that info. Hundreds of millions of vehicles have them, and are in no danger of being extinct.
"Idiot lights" were created to bridge the gap to indifferent operators.
Madass sells a kit for these bikes.
There are plenty of crankcases perforated from "just riding it", unaware of the downtrend in oil pressure, until one day, it soils the sheets.
NO gage is meant to be stared at.

You always look at the speedo and tacho, I don't see the difference.

Exactly, a millisecond glance..

concours said:

Exactly, a millisecond glance..

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The gauge I have the needle just points straight up,if all good, don't even need to see any numbers.

Shelby-Right said:

The gauge I have the needle just points straight up,if all good, don't even need to see any numbers.

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I have a gauge on all four of my bikes. As I have said many times before Ignorance is not Bliss.
Having two Enfield Interceptors which suffer from chronic low OP, the gauge provides a means of collecting data to form some sort of idea of what is going on. The hotter the ambient the greater the pressure drop. A long pull up a hill will show a big drop but it recovers reasonably
quickly when the grade levels off.
The Norton will hold 42 pounds once warm fading to 35 under very warm temperatures.
The Trident with a fresh overhaul will have no problem exceeding 60 even on the hottest day.
So seems to me that the lubrication system on old brit bikes was usually marginal. We do not
see low OP on modern bikes or cars. And we don't see rods coming through the cases or
short TBO either. Agree with the idea flow is at least as important as pressure. Agree that
oil pressure does NOT float the crank. The layer of oil protection is likely only molecule level
thick .
I remain in awe of Ludwig's low pressure event and his willingness to go gauge free.

Like house pricing is location,location and location, bearing performance is oil film thickness, oil film thickness and oil film thickness.

To calculate Oil film thickness the oil pressure is irrelevant.


All the oil pressure gauge showing is that oil is flowing.

Of much more importance is the ability of the oil to create good oil film thickness and that it is clean.

Shelby-Right said:

You always look at the speedo and tacho, I don't see the difference.

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Not the same thing. You can ride for hours without once looking at speedo or tacho.
If you don't check your oil pressure gauge every two minutes or so, it is pointless to have one.

ludwig said:

If you don't check your oil pressure gauge every two minutes or so, it is pointless to have one.

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Not really.

If the gauge shows something different from usual, such as slowness to build up pressure from starting, or a falling-off during long rides, that’s useful information that you can get from an occasional glance.

If anyone cares, I don’t have an oil pressure gauge on my non-Norton twin. I don’t want the extra three feet of high pressure hose and fittings tapping into the oil system. Others are happy with all that.

I do have a pressure warning light. It tells me less than a gauge, but it’s robust. I like to see it behave consistently.

kommando said:

Like house pricing is location,location and location, bearing performance is oil film thickness, oil film thickness and oil film thickness.

To calculate Oil film thickness the oil pressure is irrelevant.

How to Calculate the EHL Oil Film Parameter

When designing an application, the design engineer must consider proper bearing lubrication. The lubrication method affects the proper operation of the equipment and the cost of maintaining it. Once the lubrication method is determined, selection of the proper lubricant oil viscosity is vital...

www.pumpsandsystems.com

All the oil pressure gauge showing is that oil is flowing.

Of much more importance is the ability of the oil to create good oil film thickness and that it is clean.

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ludwig said:

Not the same thing. You can ride for hours without once looking at speedo or tacho.
If you don't check your oil pressure gauge every two minutes or so, it is pointless to have one.

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Disagree.

Trends. It's about trends.

Not the "oil hose slipped off and ran dry" scenario.

concours said:

Disagree.

Trends. It's about trends.

Not the "oil hose slipped off and ran dry" scenario.

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Ok, you have a point here, but still, if I wanted to add another instrument on my bikes, it would be a tire pressure monitor, not an oil pressure gauge.

For me, it is important that the conrods don't lock up on the journals and then destroy the crankcase, I would rather just rebuild a worn out engine. I use a small braided line with proper fittings, I don't like push in air fittings, we all have our own preferences, if we were all the same, it would be boring, and have nothing to say on the forum .

In near 50 years with my Norton i have never used a pressure gauge or any oil light, nothing at all, i have a Smiths 100 psi oil gauge for as long still new in the box, i was going to mount it between the speedo and taco and have all the fitting but all these years of not running one and hearing all the folks from here running on very low pressures i decided i didn't need one, just worrying about something and looking at the gauge all the time, no thanks.
I run good classic Pentrite oil but i also mix STP with my oil and have been so since 1982 as well a Lochead oil cooler all year round including winter, some say snake oil but i have had very long life out of my motor and clocked up over 150k miles doing this, snake oil i don't care what others say but it works for me and my motor and bike is ridden hard all the 50 years of ownership.

Ashley

ashman said:

In near 50 years with my Norton i have never used a pressure gauge or any oil light, nothing at all, i have a Smiths 100 psi oil gauge for as long still new in the box, i was going to mount it between the speedo and taco and have all the fitting but all these years of not running one and hearing all the folks from here running on very low pressures i decided i didn't need one, just worrying about something and looking at the gauge all the time, no thanks.
I run good classic Pentrite oil but i also mix STP with my oil and have been so since 1982 as well a Lochead oil cooler all year round including winter, some say snake oil but i have had very long life out of my motor and clocked up over 150k miles doing this, snake oil i don't care what others say but it works for me and my motor and bike is ridden hard all the 50 years of ownership.

Ashley

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A short time after I breathed my N15CS back to life from a 40 year dormancy, I had an oil feed hose to the head come off. My fault, all better now with a proper crimped arrangement from the Mesa hose shop nearby. Anyway, shortly after kicking it over, it gave way, and it splorched my car's door pretty good. I figured, man, that's good oil pressure right there, I'm all set!

I think people just over think and worry about things that may never happen, whether i have a freak Norton i don't know, it was a everyday rider most of the 50 years i have owned it or just lucky who knows but i do thank my Norton after every ride when i get home and give it a pat on the tank for a great day out and getting me home safe.
So worrying about what may happen, no that is just not me, ride and don't think about and enjoy your day out on your bike.