Oil pressure gauge off the dial

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Mic

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just fitted an oil pressure gauge but upon start up the needle jumped to the 100 psi limit on the gauge and could go no further,it has remained there with the motor no longer running .....gauge broken I assume....any ideas why this would have happened? Thanks in advance to members
 
Yes, I have an idea as to why that has happened. In respect of the gauge not returning, there is a (somewhat unlikely) possibility of a blockage not allowing pressure to release, and as you mentioned the gauge may have been damaged, so is merely "jammed".
As far as the gauge hitting 100 psi, it may be as simple as you have more than 100 psi of oil pressure (on cold start-up). With thick oil, cool temperatures, a new (or at least top condition) oil pump, and plenty of shims in the OPRV, that pressure is obtainable, especially if the rpm are not kept in check.
 
I had a situation once, where, at 5:00AM, I accidentally pinched off the oil tank vent hose that ran along rear loop with a bungee cord. Gage pegged. So, a failed breather line could do that.
 
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Thanks for your reply CCR....anyway I can un jam the gauge? I paid good money for this gauge and wish it had the ability to withstand the extra pressure and not have topped out...hmmmp
 
Gauge appears to be a sealed unit...most gauges I have seen advertised suitable for Nortons only read up to 100 psi...I would love to know what oil pressure the bike has and if it comes down to a more normal level when the oil is hot....the pressure relief valve is shimmed enough to just feel a slight rattle
 
Mic said:
Gauge appears to be a sealed unit...most gauges I have seen advertised suitable for Nortons only read up to 100 psi...I would love to know what oil pressure the bike has and if it comes down to a more normal level when the oil is hot....the pressure relief valve is shimmed enough to just feel a slight rattle
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There is not a default need for shims in the OPRV. They may well be, and clearly are, required in some instances, but 70lbs with no shims, and not overly heavy oil, is neither impossible nor unheard of, dependant on other factors.

Of course, in some instances there is zero pressure without some shims.

I use gauges that read to 60LBS, but they can tolerate up to 80 lbs without "pegging out". My test gauge is a 100lb type.
 
Mic said:
I’m not sure what to do now....any ideas?
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Yes. Obtain a reliable (test) gauge 100lb is a good idea (which you may have already done, and inadvertently damaged it). Remove all shims from the OPRV, and ensure the spring is not modified. Start engine, and make sure oil pressure is indicated (pretty much) immediately.

Keep revs to a fast idle only. If it looks like the gauge is going to be exceeded (which is difficult to believe if there are no shims) shut down before it does.

Assess from there.

Of course, if the relief path for the excess oil from the OPRV is blocked (I do not know what model you have), then the shims (or lack of) will have no effect.
 
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Classic Cycle Repair said:
Yes. Obtain a reliable (test) gauge 100lb is a good idea (which you may have already done, and inadvertently damaged it). Remove all shims from the OPRV, and ensure the spring is not modified. Start engine, and make sure oil pressure is indicated (pretty much) immediately.

Keep revs to a fast idle only. If it looks like the gauge is going to be exceeded (which is difficult to believe if there are no shims) shut down before it does.

Assess from there.

Of course, if the relief path for the excess oil from the OPRV is blocked (I do not know what model you have), then the shims (or lack of) will have no effect.
Click to expand...
Thanks for your assistance.very much appreciated
 
One winter...At 15 deg "F", and 50w oil, I pegged a gauge out at 160psi full scale. At a slower idle it should not get that high or even close with winter oil. The OPV device usually does not need shims and will still start to limit to 55-65psi. With increased rpm the OPV DOES let the pressure go even higher.
Running and with the engine/oil warm the running pressure never opens the OPV.
Oil pressure gauge off the dial
 
Mic was your gauge digital or analogue if it has a needle the principal of these gauges use a bourdon tube as it expands with pressure it turns a drive wheel which is attached to the needle you read it is possible you exceeded the gauges pressure and jammed the needle . Most pressure gauges are best selected to read at 2/3 rds of their maximum pressure . As already mentioned with cold oil you may have blown the gauge if you release the gauge line to vent to atmosphere and it still is at max you have blown the gauge .
 
dynodave said:
One winter...At 15 deg "F", and 50w oil, I pegged a gauge out at 160psi full scale. At a slower idle it should not get that high or even close with winter oil. The OPV device usually does not need shims and will still start to limit to 55-65psi. With increased rpm the OPV DOES let the pressure go even higher.
Running and with the engine/oil warm the running pressure never opens the OPV.
Oil pressure gauge off the dial
Click to expand...

How did you spin up the pump assuming the pump on the crankcase was doing the pumping?
 
dynodave said:
Running and with the engine/oil warm the running pressure never opens the OPV.
Click to expand...

I do not believe that to be true.
If that were true, then adding a shim would have no effect on warm running pressure.
But it does.

I have seen that statement previously, that the OPRV remains closed, but I do not think it is ever "closed" when the engine is running.
The idea that the oil pump is only making 30 lbs pressure, so the valve must be closed, is a completely faulty conclusion.

The spring is understandably easier to compress initially, resulting in pressure losses at low readings.

I have conducted a range of tests involving adding shims to hot engines, etc, and have concluded that the OPRV is always bleeding pressure to some extent, dependant on oil viscosity, temperature, actual pressure reading at a given rpm, etc.

The result was always the same. The pressure reading increased with the addition of a shim, even at idle.

At some point, at idle, adding more preload to the spring will cease to have an effect, as the valve will be held closed throughout, but that will translate through to a higher maximum reading as well, which could be quite high if the OPRV is actually coil bound prior to the relief aperture being revealed.
 
Gauges ar
dynodave said:
One winter...At 15 deg "F", and 50w oil, I pegged a gauge out at 160psi full scale. At a slower idle it should not get that high or even close with winter oil. The OPV device usually does not need shims and will still start to limit to 55-65psi. With increased rpm the OPV DOES let the pressure go even higher.
Running and with the engine/oil warm the running pressure never opens the OPV.
Oil pressure gauge off the dial
Click to expand...

Love that I can date that photo by the Molsons beer logo
 
Twer it my pressure gauge, I would take it off and hope that if I sat it on the bench that it would read zero in the morning. If it didn't I would gently tap, suck on the fitting and curse until I got frustrated and decided to do something potentially damaging to the unit. But then I always start with the least destructive and work my way up to full on "let's see what's inside of this thing" mode.

Where is the gauge tapped into the lube system?
 
Im sort of in the midst of this myself. But we are talking RE Interceptor. Cold it can see 85psi with the OPRV set to go at 60.
This is room temperature and 20-50 oil. If I ran straight 50 Im sure it would peg the gauge at 100. Once warm the pressure
drops right off and hot it sinks seriously. Granted two completely different pumps involved. The relief valve may not be
able to dump enough oil fast enough when cold.
 
L.A.B. said:
How did you spin up the pump assuming the pump on the crankcase was doing the pumping?
Click to expand...

I machined a dummy shaft to act as the crankshaft to drive the pump with either 3 or 6 start gear. There is a 1/4 hp DC motor, 0-130VDC 0-2700 rpm driving the shaft through a lovejoy coupling. I can seperately test the OPV pressure & flow by ball valving it in or out of the circuit.
There is a crank speed optical tach read out above the oil temp readout. My variac controlled power supply controls the speed.
OPV is fed by normal timing cover gallery. OPV output is entirely run through the VA meter on the left. It only shows flow (other than OPV thread leakage) when OP is reached. If there is flow you see it on the meter.
Regular oil pump flow is out the front where the crankshaft lines up. Oil pump flow is measured on the VA meter on the right. There are no other outlets from the timing cover gallery except the Lab 0-100PSI gauge on top.
This was a bit of engineering and machining to make this set up but it's not rocket science either.

Oil tank in the rear behind the 100psi gauge is a mid 50's ES2. Surplus race cracked combat cases.

Oil pressure gauge off the dial
 
rvich said:
Twer it my pressure gauge, I would take it off and hope that if I sat it on the bench that it would read zero in the morning. If it didn't I would gently tap, suck on the fitting and curse until I got frustrated and decided to do something potentially damaging to the unit. But then I always start with the least destructive and work my way up to full on "let's see what's inside of this thing" mode.

Where is the gauge tapped into the lube system?
Click to expand...
Tapped into the left side rocker feed
 
Onder said:
The relief valve may not be
able to dump enough oil fast enough when cold.
Click to expand...

You are quite correct. The cracking pressure is where it "starts" to open up (flow on the va gauge). With cold oil, the higher the flow with higher RPMs, the OPV can not full keep up but does significantly moderate the over pressure. A OPV opening at 55-60 will run well over 70 psi at speed.
I however have noted the NEW SRM OPV have a different spring winding and regulated the over pressure much better than the original norton ones AND the OPV thread bypass leakage is much less.
 
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I have a oil pressure gauge set up that I purchased off of ebay, it came from Greece. It worked great for a year or so then about 3 weeks ago I was out for a ride and the nylon hose pulled out of the fitting on the engine. Ruined a pair of boots, well the left one, and a pair of pants. Fortunately I caught it before the oil tank was emptied. I had the original set up with me and I re-installed it. On inspection I noticed that there wasn't a compression sleeve to crimp the hose to the fitting which I believe lead to the hose blowing off. Tried to find a compression sleeve / olive to fit the nylon hose
Oil pressure gauge off the dial
olive and the hose size is between the 2 and 3 size from Weatherhead, 3 being to big and 2 is to small to fit over the hose. Here is a picture of the end that blew off. If and when I do replace it I will use a 1/4" hose and a double banjo not this sort of silliness.
John in Texas
 
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