Just a little insight into the oil side of the VRO2/OMS

[cfauvel]

Wanted to share some of my findings about the oil side of the VRO2/OMS


I have been plagued with some dripping oil from my VRO and wanted to address it.

Tightening the clamp on the hose at the inlet didn't help so decided to figure out where it was leaking from.....now I know


found the leak to most likely be the top o-ring on the pin that used to count the pulses




Cleaned up





what is going on the opposite side of the oil electronic and chamber







The pin that goes to the electronic side is an activator of a set of tiny contacts.
The o-ring is the pivot point, as oil pushes up on the fuel side, it pushes down at the opposite side and indirectly closes the contacts, which must be registered in the electronics and counted.







Whilst I had the pump off I replaced the o-rings for all the inlets and outlets and inspected the air motor and fuel pump (both were fine).

did some vacuum tests once all back together and tested fine...

will run off of a pre-mixed gallon of fuel, test the NO-oil circuit and test that indeed oil is being drawn in via a clear tube connected to the oil inlet..

When I get the parts back together I'm going to take a video of the counter doing it's thing..

Being a frustrated Mech Engineer I like that they went mechanical to do the counter, rather than some tricky impedance mechanism like I thought it was.

(Correction 07/05/2017- the pin is NOT a counter, rather it is counter RESET, the counting takes place in the electronics based on TACH pulses (not revolutions per minute) )



compare the number of closed contacts to the revolutions per minute and if not in the right range no-oil alarm sounds....initially decades ago I thought the electronics did the pumping, it wasn't until another decade or so when I read that VRO bible on Continuous Wave that the electronics had no bearing on the pumping of oil.

Would love to know the chart between counts of oil cycle to revolution per minute.
(Correction 07/05/2017 - the electronic part counts up to 8192, if it reaches that number before the reset pin resets the counter back to 0 then the alarm sounds)

 

[cfauvel]

The manual states the following
At WOT a 1 inch column of oil in a 1/4 ID tube should be consumed in three pulses
at 800 rpm a 1 inch column of oil in 1/4 ID tube should be consumed in 9 pulses

I can see how the travel distance of the piston varies with the amount of vacuum at the pulse fitting....


I don't have a way to simulate the pulse off the engine...Open to ideas on mechanism to simulate the engine pulses...

 

[ob]

Maybe some diaphragm or piston actuated aquarium air pump or a/c and refer vacuum pump with a rheostat control to vary pulses. IDK?:noidea: Otherwise , a very informative write up.:thumb:

 

[Bosunsmate]

A good read, i look forward to the video

 

[Fed]

8192, I thought everyone knew that.

I have NFI but I found this for you, way above my pay level & too old to want to learn it.
\http://forums.iboats.com/forum/engi...47-testing-vro-alarm-without-pulling-oil-hose
Judge Judy is on in 15 Minutes.

 

[Faztbullet]

That a newer OMS pump as it has the bolt in nipple....the 1987 OEM had glued on nipple

 

[cfauvel]

8192, I thought everyone knew that.

I have NFI but I found this for you, way above my pay level & too old to want to learn it.
\http://forums.iboats.com/forum/engi...47-testing-vro-alarm-without-pulling-oil-hose
Judge Judy is on in 15 Minutes.

LOL I was wondering what the 8192 was about

Awesome thread....going to build that gizmoe

 

[cfauvel]

That a newer OMS pump as it has the bolt in nipple....the 1987 OEM had glued on nipple

Indeed it is an OMS (hence the title) I replaced it over a decade ago...maybe even two....I'll see if can open up MS money to see if I logged the purchase.

(07/5/2017 - the current pump was purchased in 1999, so 18 years old)

 

[cfauvel]

after reading the other thread about the VRO tester over and over again. I have come the conclusion that the pin when pushed down to close the contacts is NOT a counter, but a re-setter...waiting for confirmation from that poster (super impressed BTW)...

I think the 8192 is a revolution count of the crank shaft, the electronics counts the revolutions via the tach signal, and the pin resets the counter back to 0.
(Correction 07/05/2017 - 8192 is the count of pulses, at this point I believe it is either 2 or 6....2 if it is the number of coil windings for the recharge system, or 6 if the number magnets passing over one of the two coil windings for recharge system...big difference there....if 6 then alarm should sound in 1365 revs, otherwise it should sound in 4096 revs)

if the electronics of the VRO has reached 8192 then it assumes that the pin has NOT pushed down on the re-setter contacts and sets off the alarm...

pretty ingenious little design....the only possible flaw or potential issue I see (and was mentioned in the thread) is if the tach/grey wire is cut to the VRO, or if the regulator fails and no longer sends a tach signal....if that happens the electronics will never get to 8192 or anywhere near there and remain at 0...potentially falsely thinking it always has perfect oil flow.

So good to test both the no-oil circuit and actual pump action per manual...

good stuff...

 

[Bosunsmate]

pretty ingenious little design....the only possible flaw or potential issue I see (and was mentioned in the thread) is if the tach/grey wire is cut to the VRO, or if the regulator fails and no longer sends a tach signal....if that happens the electronics will never get to 8192 or anywhere near there and remain at 0...potentially falsely thinking it always has perfect oil flow.

...

Thats quite a big opportunity for a fail considering that the lifetime of a regulator can be quite short. I would of thought/hoped there would be some kind of redundancy in the system for this event occuring but will take your advice if it seems not.
I premix mine so cant test this but i would of thought there would be the opportunity for an alarm if the VRO did not get a tach signal yet the motor was running (it would know it was running from the piston switch)

 

[cfauvel]

Thats quite a big opportunity for a fail considering that the lifetime of a regulator can be quite short. I would of thought/hoped there would be some kind of redundancy in the system for this event occuring but will take your advice if it seems not.
I premix mine so cant test this but i would of thought there would be the opportunity for an alarm if the VRO did not get a tach signal yet the motor was running (it would know it was running from the piston switch)

with my jumper wires I should be able to simulate a cut tach wire...when I get the stuff back together I'll post back the results.

as far as possible failures of oiling systems, i think MANY if not ALL system have potential weaknesses...my buddy has an older carbed mercury and the oiling is separate from the fuel pump all together if that fails there is NO warning at all. his issue was goofed up check valve that allowed oil to flow to each carb non-stop....filling the bowls with oil...


(update 07/05/2017 - my first no-oil test failed to sound the alarm, exactly because the voltage regulator was bad....it did not send a pulse to my tachometer or the VRO)

 

[Fed]

There's a big gauge on the dash that tells if the tacho feed isn't working.
There's something very elegant about running on temporary pre-mix & pulling the oil line off, waiting for the alarm then replacing the oil line and the alarm stopping.
Satisfaction guaranteed.

 

[cfauvel]

There's a big gauge on the dash that tells if the tacho feed isn't working.
There's something very elegant about running on temporary pre-mix & pulling the oil line off, waiting for the alarm then replacing the oil line and the alarm stopping.
Satisfaction guaranteed.

elegant ? not really ...simple and effective? absolutely....KISS

and you disconnect the oil line AND plug it...you don't want to suck air through the oil side....

based on 8192 magic number...at 1000 rpm, I think you'll have to wait 8 minutes for it to sound...book says 5 minutes after residual oil has been used up in VRO...seeing how little volume there is in the oil side chamber...

yeah maybe the electronic tester is a bit much....but damn that was pretty cool and learned a lot...8192!!


oh what I meant by simulating a broken tach feed, was a broken tach feed to the vro, not to the Tach...so the gauge would still be operating, but the VRO thinks there is no revolution of the crank....I will test that for sure....once I know everything is working as it should..

(Update 07/05/2017 - as stated earlier 8192 is the pulses for the Tach, not the revolutions of the crank)

 

[Fed]

I have a VRO2, our manuals must be different re testing no oil.
Don't forget the tacho runs off the stator coils so it's not 1 pulse per 1 revolution.
Stator coils are alternator coils (very nominal 12V), charge coils supply the power to the powerpack (200-300V) & Sensor coil (3V) provides the control.

 

[cfauvel]

I have a VRO2, our manuals must be different re testing no oil. .

nope you're right, my manual states to just remove the oil line....sometimes you have to re-read and re-learn

and now that I know the check valve for the oil, with the oil line off the pressure of the piston would simply push air out the oil-inlet...

Don't forget the tacho runs off the stator coils so it's not 1 pulse per 1 revolution.

not actually following you...but you might be able to help me understand...the stator coils (the 12v) there are two windings, so two pulses = 1 rev? I remember there is some setting behind the tachometer...forget the setting, but it has been working for decades.

If the tach stops, it seems VERY prudent to get that taken care of ASAP, considering the VRO needs it to know if it needs to set the alarm.

Stator coils are alternator coils (very nominal 12V), charge coils supply the power to the powerpack (200-300V) & Sensor coil (3V) provides the control.

roger that....I get the 'charge' coil mixed up with the 12v coils....

(Update 07/05/2017 - my mistake, I always call the whole unit 'the stator'...but now I get the windings with the two knobs/coils is the stator and the windings with the eight knobs/coils is the Charge Coil....thanks)

 

[cfauvel]

So looking at the VRO no oil circuit that the other poster from the other thread posted, we see that there is an IC chip,....



through some research I found this spec sheet
https://assets.nexperia.com/document...t/HEF4020B.pdf

the IC chip is a binary counter with two inputs, clock pulse and manual reset. Outputs are equal to the binary count

q0=1
q3 = 8
q4 = 16
q5 = 32
q6 = 64
q7 = 128
.
.
q13 = 8192


8192 is not an out of the blue number, it is the next binary number from 4096, (binary numbers 1, 2,4,8,16,,,, )



I don't know electronic components so I don't know if it is counting rotations of the crankshaft, I just assume that it is as it states 1000rpm => 100hz

if I knew more of what the electronic parts were doing, I'd be able to tell why OMC chose 8192 to act, rather than 4096...this is black magic stuff to me..

 

[Fed]

Count the magnets ;-)

 

[cfauvel]

Count the magnets ;-)

So since I have six magnets, the tach has its pole set to 6, which divides the pulses by 6 to give the correct rpm.

do you think the pulses to the VRO electronics is adjusted to RPM, or simply pulses, so 8192/6 = 1365 revolutions, meaning if the vro counted 1365 revolutions without being re-set then there is no oil...

if that's the case the No-oil alarm should fire off in less than 2 minutes at idle....I like the sound that the horn will blow with less revolutions....

interesting stuff...to say the least...
and today's motors have engineered the heck out of that exponentially.

(Correction 07/05/2017 - jury is still out as to the number of pulses that equal on revolution. it is either 6 or 2. 6 makes the most sense to me as there are 6 magnets rotating across the path of the stator coil
but 2 may make sense too as there are two knobs for the stator coil...using 2 as the quotient, the time it took to sound alarm is right)

 

[Fed]

That sounds better, I'm not sure what the 1000RPM 100HZ was all about though, to me HZ has always meant cycles per second.

 

[Bosunsmate]

2mins at idle does seem long but i suppose with carbs and lines to the carbs both full with premixed fuel perhaps it is enough time, but why not earlier is an unanswered question.
This 8192 seems to come from the past poster but im not sure where he got it from that that is the actual required figure, he may of set his equipment up for Q13, but perhaps the counter sets off the alarm at Q12 ie 4096