What causes oil light to be on a John Deere 425?

[Rob50056]

I just finished replacing failed plastic cam gear in my 425 with metal gear kit.
I had to replace oil pump gear,but other than that I replaced governor gear and lever.
I put two quarts of oil in it adjusted valves but still haven't put on valve covers.
The kit came with new lifters which I installed and heavier valve springs also.
It fired right up runs great,got 190 per cylinder compression test,but oil light is on.
I will measure the amount of drained oil then put on valve covers but other than low oil or oil pressure by valve covers being off what can cause oil light to stay on?

 

[bruceatlam]

Oil pump not pumping or simply a bad pressure sender ----------------

 

[Rob50056]

The only gear that stripped was oil pump gear and it was replaced.Isnt oil pump built in to crank case cover?
I started but only let it run for a minute since light was on and to adjust valves.
Can valve covers not being on keep oil pressure from building enough to shut off light?

 

[crazyal]

I wouldn't think the valve covers off shouldn't have any effect. The oil light is most likely just oil pressure but it could be oil level too. With the valve covers off did any oil come out while it was running?

 

[Rob50056]

I wouldn't think the valve covers off shouldn't have any effect. The oil light is most likely just oil pressure but it could be oil level too. With the valve covers off did any oil come out while it was running?

Oil was coming up by pushrods and running out a bit.
I put valve covers on,light still on.
I rechecked oil level it didn't leak enough to be slightly below full.
I pulled off oil pressure sensor and started for one second and it has pressure,but how much I don't know.Oil squirted out about 18 inches from hole where sensor goes.
I put sensor back on and tried again light still on.
Other than replace oil sensor I see no way to test it unless I get some type of oil pressure measuring tool.
Would oil squirting out of sensor hole support that oil pump is at least working?
Any suggestions where to go from here?

 

[mrmikey]

Would oil squirting out of sensor hole support that oil pump is at least working?

It would sorta but you'd have no idea of the pressure, it takes nothing to force oil out of an unrestricted hole so not really reliable.

.......unless I get some type of oil pressure measuring tool.

Yup, a pressure gauge, manual oil pressure gauge - Google Search ..............Mike

 

[Coyote machine]

Save the money and just buy a new sender, and see if the results change.

 

[beenthere]

Rob found the problem.. in this thread (I think).
http://www.tractorbynet.com/forums/john-deere-lawn-garden/381330-how-can-i-test-oil.html#post4795848

 

[Egon]

Rob found the problem.. in this thread (I think).
http://www.tractorbynet.com/forums/john-deere-lawn-garden/381330-how-can-i-test-oil.html#post4795848

:thumbsup::thumbsup:

 

[Rob50056]

:thumbsup::thumbsup:

Yes I got it fixed.
When I removed oil pump gear the spring that sits on check ball stuck to cover and wasn't installed when reassembled.
I was looking at diagram of oil pump and immediately knew the spring wasn't in place so I went back to where I put new gear on pump and there was spring laying on floor where fell off back of oil pump cover.
Pulled crankcase cover,installed spring,and oil light no goes off after starting.
I mowed about an acre and I think my ignition module shot craps.
It doesn't fire on left cylinder now so I'm a bit stumped.
I switched left and right coils and spark plugs and both coils are fine for the right side still fires.