Good Thing I Have an Oil Pressure Gauge!

Dan1950 said:
That's why I like spray Coppercoat. It seals well but releases when disassembled. I've used it for years on all types of gaskets including head gaskets.
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Earlier in the life of this thread I was wondering if you used Coppercoat that you mentioned months ago on the composite gasket.

I have a 15 year old can of Coppercoat on the shelf I used on a Toyota head. It does work well, and is about 900% easier to work with than Pliobond is. I thought about using it on my last drop down of the Norton head, but did something silly and used a 49 year old can of brush on aluminum paint like I did in the olden days. So far so good, but I haven't tried passing anybody going uphill yet with the current engine configuration. Passing cars in the mountains is what caused my base gasket to weep a little on my previous higher CR incarnation of the Norton engine. Good engine test passing long lines of cars.

Anywho, enough of my hog wash in the Commando forum. I wish you the best of luck with the whatever the oil pressure situation ends up being.
 
MikeG said:
Yes. Test don't guess someone once told me.
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Even the very reliable Mikuni injection oil pump gets a quick verification of flow, only takes a moment.
Good Thing I Have an Oil Pressure Gauge!
 
Fast Eddie said:
Dan, any conclusions with your oil pressure situation ?
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Schwany said:
See Dan's OPRV post

In post #14 it looks like the solution was found.
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74ok said:
post #14 Dan1950
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While modifying the 0PRV did boost oil pressure, after the engine warmed up the same scenario repeated itself. It seems to be all temperature and RPM related. My oil supply line from the tank seems to be awfully soft and I'm wondering if that isn't the culprit. After the oil gets hot and the oil pump is pumping a large volume of oil, maybe the line is being sucked closed.

I've been procrastinating but I need to go home this week and do a few things so I'm going to get some transmission oil cooler line from NAPA, inspect the outlet screen on the tank and replace the oil line.
 
Dan1950 said:
While modifying the 0PRV did boost oil pressure, after the engine warmed up the same scenario repeated itself. It seems to be all temperature and RPM related. My oil supply line from the tank seems to be awfully soft and I'm wondering if that isn't the culprit. After the oil gets hot and the oil pump is pumping a large volume of oil, maybe the line is being sucked closed.

I've been procrastinating but I need to go home this week and do a few things so I'm going to get some transmission oil cooler line from NAPA, inspect the outlet screen on the tank and replace the oil line.
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I have also seen other hoses delaminate or bulge internally, definately replace .cheers.
 
Dan1950 said:
While modifying the 0PRV did boost oil pressure, after the engine warmed up the same scenario repeated itself. It seems to be all temperature and RPM related. My oil supply line from the tank seems to be awfully soft and I'm wondering if that isn't the culprit. After the oil gets hot and the oil pump is pumping a large volume of oil, maybe the line is being sucked closed.

I've been procrastinating but I need to go home this week and do a few things so I'm going to get some transmission oil cooler line from NAPA, inspect the outlet screen on the tank and replace the oil line.
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No. To have a hose suck flat, you would need a restriction upstream and a good amount of suction force from the pump. There is very little suction created by these gear type pumps and oil will move easily from tank to pump by gravity alone, more so when hot and lower in viscosity.

Pump pressure will always drop as oil heats up. I get 30-40 PSI at idle for first few minutes from cold start. Then once fully warm, only 8-10 PSI at idle. If very hot, say after sustained hill climb or stuck in traffic hot day, I will have less than 5 PSI at idle. Returns to 8-10 PSI once moving along well for a bit.
 
Tornado said:
No. To have a hose suck flat, you would need a restriction upstream and a good amount of suction force from the pump. There is very little suction created by these gear type pumps and oil will move easily from tank to pump by gravity alone, more so when hot and lower in viscosity.

Pump pressure will always drop as oil heats up. I get 30-40 PSI at idle for first few minutes from cold start. Then once fully warm, only 8-10 PSI at idle. If very hot, say after sustained hill climb or stuck in traffic hot day, I will have less than 5 PSI at idle. Returns to 8-10 PSI once moving along well for a bit.
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FWIW Got exactly that on long ride Tuesday with 82F air temp.
 
Tornado said:
No. To have a hose suck flat, you would need a restriction upstream and a good amount of suction force from the pump. There is very little suction created by these gear type pumps and oil will move easily from tank to pump by gravity alone, more so when hot and lower in viscosity.

Pump pressure will always drop as oil heats up. I get 30-40 PSI at idle for first few minutes from cold start. Then once fully warm, only 8-10 PSI at idle. If very hot, say after sustained hill climb or stuck in traffic hot day, I will have less than 5 PSI at idle. Returns to 8-10 PSI once moving along well for a bit.
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I don't think you're grasping just how drastic my oil pressure drop is. I can be cruising along with 45 lb of oil pressure and within less than a minute it will drop to nothing on the gauge.
 
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Dan1950 said:
I don't think you're grasping just how drastic my oil pressure drop is. I can be cruising along with 45 lb of oil pressure and within less than a minute it will drop to nothing on the gauge.
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Seems if true the engine should be seizing up by now? Have you confirmed gauge reading is reflecting reality?

A blockage as you suggest on feed line would not appear then later disappear. A vacuum flattened hose will remain that way until the pressure can equalize. That won't happen while pump is still running.
 
Tornado said:
Seems if true the engine should be seizing up by now? Have you confirmed gauge reading is reflecting reality?

A blockage as you suggest on feed line would not appear then later disappear. A vacuum flattened hose will remain that way until the pressure can equalize. That won't happen while pump is still running.
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I also have an oil pressure warning light and when I experience the oil pressure drop it will start to flicker at idle.
When I shut off the engine and let the bike sit for several minutes, I can restart it and oil pressure will return to the same PSI as before the drop. However, unless the bike has cooled down significantly, the oil pressure problem returns in a shorter period of time and when the bike has been ridden from a cold start.
 
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Dan1950 said:
I also have an oil pressure warning light and when I experience the oil pressure drop it will start to flicker at idle.
When I shut off the engine and let the bike sit for several minutes, I can restart it and oil pressure will return to the same PSI as before the drop. However, unless the bike has cooled down significantly, the oil pressure problem returns in a shorter period of time and when the bike has been ridden from a cold start.
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A pressure light flickering at idle is not unheard of. Would be steady on if no pressure.
Have you confirmed with a different guage? Have you confirmed oil returning to tank even when light flickering/guage showing low?

Next time it's low, try pulling a rocker line or the guage line off momentarily to confirm lots of oil spraying out. Folks have run for a couple of minutes with no rocker feed to check on rocker box drainage issues etc...no harm done.
 
Dan1950 said:
I don't think you're grasping just how drastic my oil pressure drop is. I can be cruising along with 45 lb of oil pressure and within less than a minute it will drop to nothing on the gauge.
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Hi Dan , is your oil tank still vented ? , enough ? .could you be getting to the point when the tank is holding the oil back ? , mine had some low oil pressure but was just the seal on my pump and now it will stay at 54 psi or so at 65-70 all the time .cheers .
 
Dan, refresh us, is the oil pump new? Or modified to have O-rings?
Get a new oil pump on hand, and bolt it on to test.
You have so much time & $$$$ in that engine, it would be a shame to ruin it
 
Tornado said:
A pressure light flickering at idle is not unheard of. Would be steady on if no pressure.
Have you confirmed with a different guage? Have you confirmed oil returning to tank even when light flickering/guage showing low?

Next time it's low, try pulling a rocker line or the guage line off momentarily to confirm lots of oil spraying out. Folks have run for a couple of minutes with no rocker feed to check on rocker box drainage issues etc...no harm done.
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There's nothing wrong with the oil pressure gauge. I put over 4,000 miles on a bike and I know what normal oil pressure was before the rebuild.

The bike always carried about 10 psi hot when idling and the oil pressure light never came on or flickered as long as the engine was running.

This isn't my first rodeo you know!
 
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concours said:
Dan, refresh us, is the oil pump new? Or modified to have O-rings?
Get a new oil pump on hand, and bolt it on to test.
You have so much time & $$$$ in that engine, it would be a shame to ruin it
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I have a new oil pump on the bench but it's also much easier to replace an oil line.
 
I've posted this before but here goes again how a gauge saved me:

MK III with the conical seal on the timing cover. I noticed that it was wet sumping which the bike normally doesn't. Other than that oil pressure was normal until it wasn't. The pressure dropped to zero or so idling with 20 or so riding. i found the conical seal split. My conclusion is that when I first notice some wet sumping the seal was starting to split and when the pressure dropped suddenly it was when seal gave way. This happened twice. My gauge pegs on startup so I ride easy until it comes off the peg. Normal cruise around 3000 is 50-55psi 10+ idle hot.

I now am alert for any wet sumping after only a week or so. Of course on longer non use periods it will wet sump a bit so I expect that.

With the conical seal blown oil return to the tank is totally normal, so that tells you nothing other than the pump is working not that pressure is being fed to where it needs to go.
 

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