520xi oil pressure guage and light not working

[RedMaine 1]

I have a low hr 520xi, and recently had some summer help using it.  The boys just used it to pull a cart with brush.. starting and stopping the tractor many times.  When I went to use the 520, it would not turn over, and I assumed that the battery was dead.  After charging the battery and realizing that there was something more than a possible dead battery, I thought maybe the soleinoid was faulty or a loose wire.  I checked all the connections, and could not find any that were loose or disconnected.  However, after fussing with it, the tractor turned over and started.

 

All seemed ok, except that now the oil pressure light was on, and the oil pressure gauge was pegged below the red.  I pulled off the air filter, and the plate and the connection was solid to the sender.  I fully believe is is a connection issue, and think there must be something that I disturbed with the starting issue. 

 

As an aside, the ground to the battery was not properly tightened, and that resolved the starting issue. 

 

I did take out the 3 relays, and interchanged them to see if one of them was not working.  I checked the fuses as well.

 

any insight would be much appreciated!

 

Mark

[RedMaine 1]

Oh, yes the oil level is proper, and recently changed.  The engine sounds fine, and I have let it run for several minutes.  But I am very nervous without the gauges.

[shallowwatersailor 3,213]

I would try to jumper the oil pressure sensor as it is normally open and see if your warning light goes out. The Oil Temperature is a different circuit.

[RedMaine 1]

Jumper..  do you mean pull the wire off and ground it?  The oil temp started working again.. but I think that possibly the key switch is failing..  as it has been intermittent.. 

[shallowwatersailor 3,213]

Jumper..  do you mean pull the wire off and ground it?  The oil temp started working again.. but I think that possibly the key switch is failing..  as it has been intermittent.. 

What I mean is to take the two wires off the oil pressure sensor and run a jumper wire between them. That way you can tell if that is the problem. If it doesn't make any difference the pressure switch should be good and the problem is elsewhere. Don't continue to run it without the pressure switch in the circuit though!

[RedMaine 1]

OK..  so I replaced the oil pressure sensor, and the problem still exists.  I changed the oil and filter as well.  cleaned up all the connections. The temp gauge works, I was not running the motor long enough to make temp ..  any other thoughts?

[Martin 2,132]

I know nothing about these engines, but right now I would be temporarily swapping in a mechanical gauge and seeing if you have oil pressure. If not, sounds to me like its a bit more internal, oil pump or relief valve (if relevant to the engine).

I would be worried about running it a long time until you know for sure.

Sent from my iPhone using Tapatalk

[doc724 925]

OK, just to be clear, and following up on what John Matthews has said.  The oil light is connected to a pressure switch.  It is a close on (pressure) rise and it will close at about 20 psi.  The oil pressure switch is located down low on the block (right side if memory serves me correctly).  The temperature sensor (it is an analog device, probably a thermistor), is located at the top of the engine, under the air cleaner assembly.  If the oil light is on, it means one of 4 things 1.  There is no oil pressure  2.  The switch is bad  3.  There is an open circuit between the switch and the light  4.  There is a high resistance somewhere in the circuit between the switch and the light.  The resistance is high enough so that it looks like an open circuit  Download the service manual from Toro.  Print out the schematics and using a multimeter, measure the resistance of the oil pressure switch when running and not running.  Check all the connections as well with the multimeter. 

 

Martin's suggestion is a good one as well.  Neighbor across the street had a JD318 with similar problem. He bought a cheap oil filled gauge at harbor freight, installed it and confirmed pressure was ok.  New switch and his problem was gone.  I had a similar problem in a Chevy pick-up.  Talk about panic!  A new switch fixed the problem.

[doc724 925]

I was incorrect.  I just checked the engine service manual.  The oil pressure switch is at the TOP of the engine.  Must have gotten confused with my 314 Command Pro where it is at the bottom of the engine, close to the oil filter.