Oil & Fuel Oil siight / Temp guage

[jaquetarr]

PT,
Thanks for the scenario. Yes, it does help. I use my PT as a yard tractor. My place is too small to get far. Fortunately you had enough oil in the tank, short distance to go or small enough leak to let you get to the top safely. From your experience I can guess you did not damage the pumps. You had the experience and knowledge of your situation to make the right decision in a split second.

The ‘kill’ switch I envisioned would be at the discharge of the main pump and not activate until this pressure dropped to some nominally low value such as 50 to 100 psi. At such a low value the wheel motors would not have enough pressure to turn. Also at such time the leaking hyd line or blown seal would have passed all the oil in the tank, but the pumps / motors would have enough oil retained for lubrication and not be completely dry. Thus they would be able to be used again. Of course, in such a case it would be wise to check them for evidence of damage.

If an oil leak fault occurred while running, the operator would have time to move the tractor as long as main discharge pump pressure was in the operational range. When the pump discharge pressure dropped below the level needed to move the tractor - soon after the tank emptied - the main pump discharge pressure ‘kill’ switch would activate stopping the pump keeping it from self destructing. At that time the operator would have the option of making a temporary fix to the leak such as bypass or plug, refill the oil tank & drive the tractor again.
The switch would function in the same manner as the operator turning off the engine when the tractor stopped moving during an oil leak failure. It would be one less thing for the operator to think about. This is a conceptual idea and would need more engineering to see if it is workable.

It is not the same as an ‘in the tank’ level switch. With an in the tank switch you never would have been able to get on that 30 degree slope.

If the distance to the top would have been longer or the leak more severe and you wiped out the pump ($$$$), would your thinking be different? Who knows.

Best Rgds,
tim

 

[SwampmanLA]

Maybe I am missing something here but with a discharge pressure switch, would you not have to be out of oil to get a pressure drop? Seems to me a low oil level float, positioned at half the tank volume, is the way to go. The float would be submerged at all times even if the oil is sloshing around and would not activate until the oil volume gets low. A light,buzzer, or kill switch is your choice. Also, my 422 has an access plate at the top of the oil tank. It would be easy to remove it drill, tap, or weld in the necessary fitting for a float. Guess I'll have to look for something like that. Anybody know of a good website for control switches?

From the Swamp

 

[ponytug]

If you monitored the vacuum in the charge pump line, a break to nominal atmospheric would indicate a lack of oil in the charge line, and therefore a soon to be lack of oil in the pumps. Thus, a monitor there would be the last indication prior to pump damage.

Obviously, if the hydraulic pressure is down to 100psi, nobody is going anywere, but by that point you probably already have air being pumped into the motor circuit. I infer from PT insistence on bleeding the charge line after changing the oil filter that any air in that circuit is a problem.

I have struggled with the installation in tank switch for the reasons that jaquetar mentioned and several others; high slopes, strong fluid flows in the tank, and rapid shifts in fluid levels. Before you go drilling into the tank, you might want to look at how the oil flows with a wide open throttle. I was certainly surprised, but with 20gpm, the PTO alone is turning the entire tank over every minute, and I guess that I shouldn't have been surprised. I haven't used a sensor that would work accurately under those dynamics, but perhaps someone here does.

All the best,

Peter

 

[Gravy]

I'm pretty sure a simple float switch placed very close to the centerline of the tank would work well enough. All we need to do is detect a major fluid loss. Sloshing will only cause a transient alarm.

 

[jaquetarr]

Looks like there is a different solution for everyone. An indication of low oil level to pump shutdown to prevent damage. Lights, Horns and stop switches. It would depend on how you use your machine, on what terrain and how hard you push it.

Personally for my yard work on fairly level ground a low tank level buzzer would be good enough. Its interesting to see the different needs

With the high tank oil turnover that PT mentions, it wouldn't take long to empty the Hyd oil tank.
Rgds,
tim

 

[woodlandfarms]

Gravy... Problem with the center guage (at least on the 1850) is that there is the tunnel and the oil level is not very deep in that area.

Also, I really want to stay away from any wires on the top of the tank. Between getting dinged going under the hood, and the general thrashing my PT takes in the blackberries, wires are easy to grab and remove.

Carl

 

[MossRoad]

... I really want to stay away from any wires on the top of the tank. Between getting dinged going under the hood, and the general thrashing my PT takes in the blackberries, wires are easy to grab and remove.

Carl

Then you are going to have to mount something in a line with constant pressure to detect pressure or you are going to have to mount a fluid sensor through the rear of the hydraulic reservoir so the wires are protected in the engine compartment. That would require draining the tank, drilling it out, cleaning out the shavings, etc.... unless there is an unused pipe fitting in the rear of the tank near the bottom inside the engine compartment already.

 

[MossRoad]

Here is a link to some info about a GM oil level switch. It is not a pressure switch, just a level switch. It looks like it goes into the side of the oil pan.

Stroker Engine Build Oil Level Sensor Photo

Below is a picture of a Pontiac oil level switch with part number on the box. Again, not a pressure switch, an oil level switch.

Here's one for a malibu.
RockAuto Parts Catalog

Here's one for a Corvette.
RockAuto Parts Catalog

There are lots of them out there. Some are under $20.00. Seems like one of them should work. Someone just needs to buy one at a junk yard and figure out how it works. (not me, of course).

 

[ponytug]

Dear MR,

They are basic float switches. (KISS) I think that there are some assumptions about how steep an incline you can run a corvette on...

On the other had, if you mounted it just above the normal oil intake to the charge pump, would you really care why it was that the charge pump was about to suck air?

All the best,

Peter

 

[woodlandfarms]

That looks like it should run vertically (the engine switches) but runs horizontal? I would say that Ponytug and MR have the solution.... I have to replace all my intake hoses this spring so maybe I will drain the tank and do some drillin....

Question, If you put it above the intake, would the fluid pull (the sucking) effect the switch? I am sure there is a lot of pull on that system if it is churning a tank over once a minute... (1850 = 18GPM)

 

[ponytug]

Dear WF,

Before you tear it down, I would look at the tank and watch the oil movement. I think it might help you in your selection of location(s).

Personally, I would want to play around with one in tin can or a bucket to get a feeling for how much angle and how much turbulence they can stand. Some oil, and paintstirrer on a drill and and you could save yourself some headaches.

Just my $0.02...

All the best,

Peter

That looks like it should run vertically (the engine switches) but runs horizontal? I would say that Ponytug and MR have the solution.... I have to replace all my intake hoses this spring so maybe I will drain the tank and do some drillin....

Question, If you put it above the intake, would the fluid pull (the sucking) effect the switch? I am sure there is a lot of pull on that system if it is churning a tank over once a minute... (1850 = 18GPM)

 

[Gravy]

Gravy... Problem with the center guage (at least on the 1850) is that there is the tunnel and the oil level is not very deep in that area.

Also, I really want to stay away from any wires on the top of the tank. Between getting dinged going under the hood, and the general thrashing my PT takes in the blackberries, wires are easy to grab and remove.

Carl

Details, details... They only pay me for the Concepts, y'know?

Whadd'ya mean, they ain't payin' me? I'll get back to ya Real Soon Now, OK?

 

[Gravy]

And now for today's "Well, Duh" moment:

The float switch doesn't need to be centered. It needs to be placed just above the main suction fitting. The pump doesn't care about the oil level in the tank. It only cares whether it is sucking oil or wind.

 

[woodlandfarms]

Gravy... Elaborate please.

Also I must apologize to the PT guys. Realized my typo today... Eyes are getting bad in my old age...

 

[toy]

You know I was just thinking if you had a sight glass on the side of the oil tank and it got hit and busted then you would have in effect created yourself a problem. If the sight glass was on the side of the tank or on the cover plate and you were on the machine running it then you couldn't see the sight glass. If you wasn't on the machine running it then you could just check the oil, and I know that the oil is kinda hard to see on the dip stick, but it is doable. When I lost my rear wheel motor a few months back I knew by the sound of the machine that something wasn't right and I began looking around to see if I could tell where the leak was coming from while I was running the machine and I had a pretty good idea where the general area of the problem but I didn't make a fuss about it because my wife was there and she would have panicked and I needed to work it just a little longer but when the machine began having robotic movements I knew I needed to get her home. I put a few quarts of oil in it and headed for the garriage, when I saw the oil tracks I was leaving behind then I began to be panicked, thought I had waited too long but I made it. On my dip stick I engraved a line where the full mark should be. The dip stick on my pt for the hydraulic didn't have any markings on it , did any of yours have a mark for full and add?

 

[Gravy]

Gravy... Elaborate please.

Also I must apologize to the PT guys. Realized my typo today... Eyes are getting bad in my old age...

I had just realized something that Peter had actually previously pointed out. I somehow missed his post. Having the sensor centered is good design if you are trying to accurately keep track of the actual oil level, but that's not what is really needed. The pump doesn't suck from the centerline of the tank. The pickup on mine is near the rear bottom corner on the right side. Therefore the sensor ought to be placed as near to that as practical to monitor the oil level where it really matters.

 

[SpringHollow]

i can not believe a traditional float sensor on a shaft will work in these flow conditions. The electronic sealed style? I do not know. Pressure would be a whole lot easier but you would get almost no warning - you would probably notice the changes in the machine first. Hooked up as a shutoff device might save you.

Ken

 

[Gravy]

I think the float switch might have to be baffled to damp out some of the sloshing, but I think it would probably work well enough to provide some warning in most circumstances. It probably wouldn't be perfect, but it would be a lot better than nothing.

I've probably got a suitable stainless float switch that could be installed on a drop pipe from the hydraulic tank cover plate. I'd rig it to a bright warning light. It's just a matter of finding the time to do it.

 

[MossRoad]

Make yourself a circuit that has a time delay in it. Set it for 5 seconds. If the switch bounces around it will not trigger the alarm. If it makes for 5 seconds, then it will go off.

Just thinking...

 

[BobRip]

Make yourself a circuit that has a time delay in it. Set it for 5 seconds. If the switch bounces around it will not trigger the alarm. If it makes for 5 seconds, then it will go off.

Just thinking...

Or just let it go off occasionally and that way you know it works. If will probably go off at the same places or conditions and you will learn how it behaves in normal conditions and will notice abnormal.