Oil Lights and Gauges

[Greg Field]

I did a few really brisk takeoffs last night and actually did get the oil light to come on. The needle on the oil-pressure gauge didn't even twitch. When I shut off the bike, the oil-pressure gauge shows the pressure loss as instantly as I can read with my eyes, so I would think it would do the same if there was a pressure loss under the acceleration. Maybe not, though. More experimentation later.

[guzzi323]

I did a few really brisk takeoffs last night and actually did get the oil light to come on. The needle on the oil-pressure gauge didn't even twitch.

93674[/snapback]

Not to toot my own horn but maybe this is the next step.

http://www.v11lemans.com/forums/index.php?showtopic=8251

 

I haven't 'tried' to make the light come on since installing it because I think rod bearings are good things and I want to keep mine happy but I would expect the pressure switch to respond faster than the guage. To my knowledge most gauges of any type (oil temp/pressure, speedo, etc) have a damper in them to smooth out the readings. This little bit might be enough to make the momentary pressure drop.

But what the hell do I know? I'm just some wierd guzzi guy on the internet.

johnk

[Greg Field]

Go ahead and toot your horn. You actually tried something. I'd bet it fixes the problem, if there is a problem.

 

As for dampers, my gauge dives the instant I kill the engine, so I'm doubting it has one.

[pete roper]

I've been racking my tiny peanut brain about this and I have a feeling that the guage probably won't be sensitive enough react quickly to the momentary loss of pressure. I could be barking up completely the wrong tree here but.......

 

The actual guage is electronic. It relies on current coming from the sender that is plumbed into the oil gallery. This is provided by a switched circuit so when you turn off the ignition it will immediately drop to zero. Yup? That's all fine and dandy but what about the signal from the sender? I haven't taken one apart but looking at it and how it appears to be made it would seem to me that the most likely scenario is that there is some sort of spring loaded plunger in there which is pushed up by oil pressure and operates some sort of rheostat as it does so, a bit like a TPS but it's moveent will be *vertical* rather than *lateral*. So essentially it is much the same as the original pressure switch only it uses a variable resistor rather than a simple contact.

 

If this is the case, seeing as we are tending to see only momentary loss of pressure, (the dreaded flickering oil light issue.) I just wonder if the reaction time of the guage is going to be any better than the poxy original switch? I'd hazard a guess it might actually be even slower as whatever the contact system of the rheostat it is invariably going to impart a frictional impediment of some sort to the movement of the contact and I don't know whether it would be damped in some way or not?

 

Look, it may not work that way at all but it certainly seems the simplest, (read cheapest!) and most obvious way for such a guage/sender unit to be produced and most guages are installed to detect constant pressure and gradual loss rather than sudden failure. That being the case I have my doubts about whather the guage will actually work as a diagnostic tool for identifying cavitation or pick-up exposure.

 

Wotcher fink? Greg knows me well enough to know I'm not going to deliberately say something just to be obtuse. I'm certainly not saying fitting a guage is without merit. It's just that I'm not sure that in this situation it's going to be able to give us the information we want for a cast-iron answer.

 

Pete

[Greg Field]

It's a mechanical gauge. No electrics--not even a light.

[Guest ratchethack]

Wotcher fink? Greg knows me well enough to know I'm not going to deliberately say something just to be obtuse. I'm certainly not saying fitting a guage is without merit. It's just that I'm not sure that in this situation it's going to be able to give us the information we want for a cast-iron answer.

 

Pete

A most interesting read on it, Pete. I'd just assumed that the sender is a simple "make or break" switch. I don't recall ever seeing my oil light glowing "partially on" except when the charging system would be likely to be giving partial output under low rev's. . . . .

 

BTW - Any progress on re-locating your baffle plate design for a run for V-11's?

 

If so, any ability at Motomoda to scan & post it here?

 

Either way, I'm keen to get one installed, and I've got 2 riding Pals who'd likely be in also.

 

TIA

[mike wilson]

It's a mechanical gauge. No electrics--not even a light.

93828[/snapback]

 

The gauge is probably damped as, otherwise, it would fluctuate with pressure variations. The oil pressure varies quite a bit as the crank swings because the velocity of the crank (and therefore everything else rotating in the engine) is not constant over each cycle. Quite a bit could be anything from a few percent to as much as 20%. Don't forget, liquids are not compressible so there is no "spring" effect to soak up fluctuations. Probably only noticable at lower revs. It may be that just the inertia of the mass of the needle is enough to soak up very small cyclic changes at higher engine speeds.

 

I'm beginning to wonder just how anal this thread can become. 8-)))))

[Frenchie]

I did a few really brisk takeoffs last night and actually did get the oil light to come on. The needle on the oil-pressure gauge didn't even twitch. When I shut off the bike, the oil-pressure gauge shows the pressure loss as instantly as I can read with my eyes, so I would think it would do the same if there was a pressure loss under the acceleration. Maybe not, though. More experimentation later.

93674[/snapback]

 

Just back from 10 days around France - had same oil light problem on my new Nero Corsa 05 model - with just 2000 miles on the clock Dealer told me "they all do it" - happens during rapid acceleration from standstill - sometimes light stays on even in 2nd gear Been told I should be using 15/50 Semisynth oil - was using 10/40 semi - any other suggestions? New to Guzzi - lovin' it!

[richard100t]

Just back from 10 days around France - had same oil light problem on my new Nero Corsa 05 model - with just 2000 miles on the clock  Dealer told me "they all do it" - happens during rapid acceleration from standstill - sometimes light stays on even in 2nd gear  Been told I should be using 15/50 Semisynth  oil - was using 10/40 semi - any other suggestions?  New to Guzzi - lovin' it!

94055[/snapback]

My bike doesnt do it! There may be something seriously wrong with your bike. That light comes on for a good reason. Sounds like you need to get your bike looked at by a more motivated dealer.