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Discussion Starter #1
Hello all,

first let me explain that when I got the tractor it had exactly one wire. the alternator wire.

Next let me explain that my gauge cluster looked like someone took a hammer to it.

all that to explain that what im tying to do is judge the health and functionality of the tractor without spending money on a bunch of secondary parts. so what im doing is wiring in a dummy light to the oil pressure switch.

my guess in the switch is the original one from 1974.

I wired up a dummy light as per the diagram. when in turn on the toggle switch (i put this to save the battery when not in use) the light comes on. the tractor is not running.

i start the tractor, the light almost immediately goes out... then a 3 to 5 seconds later it comes back on. tried it 5 or 6 times and always does the same thing. Do yall see anything wrong with how i have it wired?

Im guess and HOPEING that its just a bad oil switch as i ran the tractor all day Saturday, this is also what make me pretty confident that its the switch. don't think it would have ran all day in 91 degree heat, bush hogging, without oil pressure.

Thanks

Wiltz
 

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Your schematic looks right. Any chance the connector slipped off of the oil pressure switch after it started? Or maybe the wiring is loose somewhere you're not aware of? I don't see how the light would go out when you first started it if the pressure switch was bad all along, and if it was good when you first started it, then it would be a heck of a coincidence that it went bad at that instant a few seconds after the engine started.

Also, does the light go out each time that you start the tractor and then come back on a few seconds later? Or did it only go out when you started it that first time?
 

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Discussion Starter #3
It does the same thing every time. Light is on, start tractor, light goes out, a few seconds later it comes back on. Not sure how the internals work but maybe it's worn causing the contacts to make ground?

All my connections are good but you did get me thinking. The led I'm using had a ground terminal. That being the case I assumed the led housing would not ground out. I bet it is grounding out. Ill test the light tomorrow isolated from the chassis ground.

New oil switch on the way ill just have a backup.
 

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Just guessing...

When you crank the engine, the battery voltage drops.
When engine is running, the generator/alternator restores the voltage.

Depending on battery condition, connections/wires to battery and bulb type, you may get the effect as you described when the sender is faulty, oil pressure is low or unwanted connection to ground is present.
 

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Discussion Starter #5
Maybe im looking at this the wrong way. I'm trying to trouble shoot the Oil Pressure light/switch, but maybe what I should be looking at is DO I HAVE OIL PRESSURE.

What would be the easiest way to be sure I'm getting oil where i should be be getting oil? Im thinking if i pull the valve cover and turn the engine over for a bit I should see oil flowing thru the top end. Would this confirm good oil pressure?

or what about just putting a standard pressure guage in the port where the pressure switch is? If this would work, what pressure should I get as a reading?

Any other thoughts?

thanks guys

Wiltz
 

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Well the first time you said you were using alight, and now you say it's an LED. There is a big difference. An LED is a diode, which means that current only flows in one direction, so when you first start it you are drawing current through the starter which causes the current in your circuit to try to flow in the opposite direction, and so the LED goes out, and then once it's started and the charging circuit kicks in then the current can begin to flow back in the other direction and the LED comers back on.

Use an ohmmeter on the pressure switch contact and ground without your LED circuit connected to it while you go through the starting procedure, and I'll bet that it stays at or near zero ohms the entire time, which hopefully is a bad pressure switch and not a true lack of oil pressure.

You could just loosen the pressure switch in the block and see if oil comes out there when you cranks the engine rather than pulling the valve cover.
 

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Sorry all, I misunderstood. I took it as there where battery connections made of lead.:eek:

Seeing oil being pumped around is no guarantee that there is enough engine oil pressure. Engine oil pressure should be 60-70 psi at 1000 rpm engine speed.

I would first switch the senders and use an ordinary 12V bulb.
 

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Discussion Starter #8
I know on Friday night yall are patiently waiting to see what I found!!! Oh, and trying to find a 12v "LIGHT" at a parts store is almost impossible.

Well here it is. first the LED. I turned the switch on, LED lit up as it should. I pulled the terminal from the OSU (oil sending unit), LED went out. started tractor, LED still out. touch LED ground to OSU, LED comes on. This confirms I don't have a bad ground somewhere. Oh, one more thing on the LED issue. I connected the OSU ground to a chassis ground. tractor off, LED on, start tractor, LED stays on, tractor running Stays on. It never goes out.

Next the OSU. tractor off, I get either 20ohms, or 110ohms. not sure why different readings but I tested it several times and id get one or the other (not those exact numbers but within 5ohms up or down). start the tractor, I get an OL (open line). 3 to 5 seconds later (just like with the LED) I have resistance. its ALL OVER THE PLACE. jumps from 40 to 100. dances around 50, drops to 2 to 5 , goes back to 90. Just all over.

So I think the switch must be jack up. New one will be in early next week so ill see what happens with it.

any thoughts would be appreciated.

And here is a pic of my $45 home made oil light and water temp gauge.
(once I get the tractor running and I know its a strong machine ill get a new ford gauge and hook it all up properly. just trying to get some monitoring done on the cheep.) you will also notice my new steering wheel. you may remember my makeshift wooden one in had made. This got the old ford knick named Frodo (the hobbit). My buddy said "that looks like a hobbit tractor"... Ford-Frodo. Hey it works.
 

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Discussion Starter #9
Here's me gauges. ImageUploadedByMyTractorForum Free App1370653914.788189.jpg


Sent from the MTF Free App
 

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Does sound like there's something screwy with that pressure switch. The fact that you get different symptoms if you attach a separate ground wire to the body of the pressure switch sounds like the threads are insulated from the exposed part of the switch housing, otherwise you would get the same symptoms with or without your extra ground wire. Also sounds like something is moving inside the pressure switch when the pressure first comes up but whatever it is that moves and opens the circuit isn't staying where it moves to and is settling back to its original position.
 

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Discussion Starter #11
ImageUploadedByMyTractorForum Free App1370817103.897628.jpg well, inpatients, curiosity, and boredom got the best on me. When to O'reilies and picked up a oil pressure gauge. I think this is better than a dummy light anyway. Getting pressure between 60 and 70 psi.

Thanks for the help guys

Wiltz


Sent from the MTF Free App
 
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