Oil Pressure

[chotus52]

Just removed, cleaned & reseated the prv . Running Penrite 30 oil 20/w60. Oil pressure now 30psi cold reducing to 20psi at idle & 25psi when riding when warm

[chaterlea25]

Hi,
Those figures are too low for my liking 
PRV should open at around 55psi and feed oil to the cam trough
I would either get the PRV tested or substitute for a known value one

John

[Colsbeeza]

An update on my experience with oil pressures,
I have completed my engine repair and the GF started second kick last week (my Rt knee is a bit weak). I went for first 5-mile ride yesterday.  It ran beautifully, no noises, no spitting or backfiring, and best of all No Smoke, using IMD pistons. Note all is virtually new with 1.8 thou crankshaft end-float and new big-end shells. I had also ran a cleaning drill through the LH conrod oil hole, which had been partially blocked.
I used Penrite 15W-40 Running-In oil, have a pressure gauge fitted and cartridge oil filter in return line.
Cold start gave 60psi at fast idle. Oil returning well. Warmed up and at 35mph was 30psi - no lugging, less than 1/3 throttle. On arrival home it idled at 10psi. That sounds low but common for low-viscosity oil.
My notes from a couple of years ago indicated that when I used Penrite 15W-40 I got the same oil pressures, suggesting that my rebuild has the same resistances to oil flow and everything is normal.
Back then, I changed to Penrite 20W-60 and got 40psi at 30mph and 45psi at 35mph and 20psi at hot idle.
I will probably change to 20W-60 again at 50 miles running and see how that goes.
This may help somebody.
And Muskrats fork dampers worked a treat!
Col

[muskrat]

G'day Col.
That's great to hear mate.
That 1st ride your senses are like Superman listening for rattles and feeling for vibes.
20/60 is a good grade after run in.
Cheers

[sean]

This is why Harley fitted an "idiot" light to their bikes.

 You set the light to trip at under 5 or 10 pounds pressure, its warns an owner something is wrong.

 Put a gauge on a bike and people worry all the time.

I bought a new harley electraglide in 04 the oil pressure at idle was 10 psi as soon as the warranty ran out I pulled the motor apart and put in a feuling oil pump along with cams etc oil pressure at idle went to 20 psi and 60 on the highway .

[RDfella]

An oil pressure light only comes on around 5psi or a shade higher, unless you get an adjustable type you can set so the light comes on at your preferred danger point. In my view, an ordinary light switch is virtually useless. Imagine you're cruising along at 50mph enjoying the scenery. The oil light is out so everything is fine. But is it? Your engine could be running at 7psi. Which is why on boats we fit an alarm, usually of the adjustable kind (mine are set to 40psi). On a fine day I want to enjoy the scenery, not be permanently staring at the dashboard. Imagine again - one looks at the dash and sees 55psi. Good, so one looks away to enjoy the scenery. But a few seconds after you saw that 55psi it fell to zero. Now how long will that engine continue to run at almost full power before mechanical disaster? The alarm calls your attention to the dashboard, where you'll see there's a problem and take appropriate action. Could be low oil pressure (pipe failed etc) or overheating, but at least you've saved the engine, which on pleasure boats usually start around £10k and rise to £100k depending on boat - and that excludes most boats 70ft or over.

[Triton Thrasher]

What faults cause loss of oil pressure as you’re riding a BSA along the road?

Can’t happen very often.

[Greybeard]

Harking on about my Austin Seven again:
Oil pressure is rather over rated.
On the dashboard was a button that protruded slightly from its bezel if there was oil pressure, (can be seen behind the steering wheel in the picture). Those engines had very low oil pressure anyway; 5lbs when hot. Two nozzles in the crankcase directed a stream of oil at troughs on the crankshaft webs that had drilling into the big end journal's. Most of the engine lubrication relied on oil splash and mist.

PS. Note, only two crankshaft bearings!

[Greybeard]

What faults cause loss of oil pressure as you’re riding a BSA along the road?

Can’t happen very often.

Loosing all the oil?

[mikeb]

What faults cause loss of oil pressure as you’re riding a BSA along the road?

from my limited experience with BSAs I've already observed:

• broken takeoff to the head on the return side near the oil tank. the bike ejected all oil (some of it over me, following behind). bottom end failure.
• a blockage in the oil tank return stand pipe that lead to oil being ejected from the engine breather all over the tyre and road. the owner stopped coincidentally just in time.
• loss of pressure likely due to a very poorly fitting PRV and the engine (in summer) working hard, then idling, then working hard. bottom end damage.

and that's just what I've seen. I'm currently installing a pressure switch

[Triton Thrasher]

What faults cause loss of oil pressure as you’re riding a BSA along the road?

from my limited experience with BSAs I've already observed:

• broken takeoff to the head on the return side near the oil tank. the bike ejected all oil (some of it over me, following behind). bottom end failure.
• a blockage in the oil tank return stand pipe that lead to oil being ejected from the engine breather all over the tyre and road. the owner stopped coincidentally just in time.
• loss of pressure likely due to a very poorly fitting PRV and the engine (in summer) working hard, then idling, then working hard. bottom end damage.

and that's just what I've seen. I'm currently installing a pressure switch

That makes sense and a pressure light will give you a warning of that situation, if a bit on the late side.  Probably better than a gauge. 

Maybe the oily tyre or footpegs will sometimes be noticed first!

A gravity fed gear pump is a very reliable system.  I expect that’s why they reckoned they could get away with having no pressure indication.

I prefer to use a gauge as a test instrument, in the garage, rather than permanently fit it to the bike.

[mikeb]

a pressure light will give you a warning of that situation, if a bit on the late side

maybe i should learn from RD's nautical perspective and get an enormous alarm or a large siren with flashing lights.
I agree about the gauge - another distraction on the bike

[Radlan2]

Hi Folks
     I have never seen this mentioned before perhaps it should have its own postas it is a critical check when assembling a re-furbed motor. Hopefully you can see the pics which show the oil hole in the main bearing bush was not aligned with the groove in the crankshaft, it was blanked off by the outboard part of the main crank journal. I would say the hole was about 95% blocked and though some oil would find its way to the big ends the motor would not last long.
      I nearly missed it to and I am pretty fussy, so easy to take such a basic dimention as a given. I have since checked some old steel backed types and they were also marginal, the oil gallery groove on the OD of the bush can contribute to the error.
         Just Saying
                    Chris

[JulianS]

I hoped these dodgy bushes had gone off the market. I experienced one in the mid 1970s. The most obvious symptom was oil leaking from many of the engine joints.

The first photo shows dodgy bush on left, you can see the wear mark in the bush and the position of the oil hole in relation to the journal channel. The one on the right is better.

Second photo shows position of oil holes from the outside.

Last shows another view of dodgy bush.

One of the reasons my engine went off to SRM as soon as they offered the end feed conversion for it.

[mikeb]

thanks Chris and Julian - hadn't thought of that. I have a new fancy srm bush tho am definitely going to check this when i get my crank back from the grinders