520H oil pressure sensor

[formariz 11,849]

So while doing extensive maintenance for the first time in my 96 520H I found a few surprises. Oil pressure light which is supposed to flash when key is turned and then go off once tractor starts, never really worked, so I thought. However upon very close inspection and cleaning I found that someone fabricated a very precise circular black dot which was placed over the light. Believe me, it was practically invisible. So light works but it always flashes. I am assuming oil pressure  is OK although I will check since it has been like this for who knows how long.

I got to the sensor which is a substantial amount of work. Tried all the suggested methods I found to fix it or diagnose if it is the light or the sensor, but light always flashes. I see also that this may not be an easy sensor to find.So although I am seeking advise on how to fix this, I am at this point contemplating adding an oil pressure gauge along with a temperature gauge for the hydro also. That wire was cut sometime in the past also looks like it may have gotten tangled in the hydro fan. I am not a fan of dummy lights and I think the two gauges would be much more useful. Everyone's thoughts and advise greatly appreciated.

[roadapples 6,981]

Like the gauge idea...

[Lee1977 6,209]

I have a oil gage on my C-120/180 with a 18 HP briggs Vanguard. It is macgincal with a small nylon tube to the gage. It's mounded below the dash in a 2" abs pipe. The tube runs around the blower housing with the idiot light wire. I have both the switch and and tube are connected at the same place with a tee.

[ericj 1,576]

did someone have the tractor apart and reverse the wires on the sensor ? they do go a certain way on the sender. just a thought

 

 

 

 

 

eric j 

[formariz 11,849]

1 minute ago, ericj said:

did someone have the tractor apart and reverse the wires on the sensor ? they do go a certain way on the sender. just a thought

 

 

 

 

 

eric j 

I tried that also. It looked like no one had ever been in there. Considering the amount of work it is to get to the sensor they may just elected to do what they did. Could very well be the actual sensor that went bad. The thing also is that to really try another one the whole engine cover has to be put back. Again, quite time consuming so perhaps just introduce a gauge and have no more doubts as to what is going on. If the oil pressure light was to activate while using it it may be too late anyway. With the gauge at least any change in pressure from normal it can be seen.

[DougC 2,641]

My oil pressure sensor/switch was leaking and I went the tough route to replace it. I agree it is no fun to remove the engine covers to get to it.

The down time waiting for the new part and the expense of shipping from the Onan dealer was ridiculous. 

I wish I would have just bought some copper fittings and pipe and converted to an oil pressure gauge. Just my experience..   

[lynnmor 6,761]

One terminal connects to ground when oil pressure is present and is the ground feed to the hour meter.  The other terminal opens to turn off the oil pressure light.  Here is a chart for Wells brand.   If you do eliminate the sending unit, remember to connect the hour meter to ground so it runs whenever the ignition is turned on.  There are sending units available that have 3 terminals, such as the PS119 available here and one terminal needs to be grounded, the factory unit is grounded thru the mounting threads.

[formariz 11,849]

Unfortunately I needed tractor and couldn't leave it apart waiting for a part. So that solidifies my decision to get both the oil pressure gauge and the hydro temperature gauge  for the next time. This way I also dont have to worry about a new sensor since gauges come with sensors. I may just have to disable the blinking light or fabricate a clever black dot like the previous owner. I have narrowed my gauge choice to a couple of digital ones that also have a warning light.

[DougC 2,641]

You and I think alike sir.

[608KEB 794]

I have a extensive post about the oil  sensor on a 520H that I have. I found the correct sensor. But, I still could not get it to work correctly. I think the post was from may 2015. 

Edited August 21, 2019 by 608KEB

[formariz 11,849]

On 8/21/2019 at 6:32 AM, 608KEB said:

I have a extensive post about the oil  sensor on a 520H that I have. I found the correct sensor. But, I still could not get it to work correctly. I think the post was from may 2015. 

I believe I have your post saved on my PC. Have no access to it now. That is another motivation to go with gauge. There will be no guess work wether it is working or not or if there is actually a problem with oil pressure. Another recent post where it was found that the pick up tube screen was clogged with crud along with the insane amount of work to get to it, just reinforces my decision.