JD 425 Oil pressure problem

[leftybob]

While puttimg my tractor away after mowing the oil light came on. I checked the oil andit was low. I added oil to the full mark but when started the light wont go out. Thinling it might be the sender unit I took it out and put in a gauge but it shows no pressure. It has no signs of locking up when run for the pressure test. Am I in for a major tear down for a oil pump repair or what do you suggest. this is a 96 year with the 20 hp Kaw. engine

 

[BBO]

Thinking it might be the sender unit I took it out and put in a gauge but it shows no pressure.

Humm...
I think I would drain the oil and see what I could see in the oil, and then change the oil filter just in case something is stopped up.
Inspect the old oil carefully. Is it a JD filter and have you changed it regularly?

I would not run it until you sort this out. Are you real sure there is zero oil pressure?

 

[Gittyup]

If it is the oil pump, not that bad a tear down. I changed mine when I changed out a broken plastic cam shaft/gear. Also changed the water pump, governor gear, push rods, and o-rings/seals. About $500 in parts and 5 hours of labor, most of which is pulling the engine and putting it back in.

 

[BBO]

If it is the oil pump, not that bad a tear down. I changed mine when I changed out a broken plastic cam shaft/gear. Also changed the water pump, governor gear, push rods, and o-rings/seals. About $500 in parts and 5 hours of labor, most of which is pulling the engine and putting it back in.

5 hours... I suspect a shop would charge ~ $1400 for all this.
I suppose you put a metal cam shaft in vs. the plastic. Mine already had the metal cam.

 

[Gittyup]

Yep, about right. They quoted $1300. Some have done it without removing the engine.

So when they replaced the cam, did they change the oil pump at that time?

 

[BBO]

Some have done it without removing the engine.
So when they replaced the cam, did they change the oil pump at that time?

I don't see how this could be done without engine removal; seems it would be harder if possible.
I did not replace my cam; it was already steel and OK. I also did not replace the oil pump.
I had a bad blow by issue and we was mainly replacing the rings.

It's still spitting some oil back into the carb thru the crankcase vent. (not much)
I do wish not I would have had it bored and larger pistons installed.
It has just over 1100 hours.
445 EFI...

 

[Gittyup]

I think it can be done in the tractor by removing the muffler, battery, and front of the tractor. Then you can get to the front cover.

It was much nicer to work on from my workbench though, and the extra work is motor mounts, drive shaft mainly. Worth it to work standing upright off a clean workbench.

 

[Rob50056]

I think it can be done in the tractor by removing the muffler, battery, and front of the tractor. Then you can get to the front cover.

It was much nicer to work on from my workbench though, and the extra work is motor mounts, drive shaft mainly. Worth it to work standing upright off a clean workbench.

I just finished mine and there's no need to pull engine.
Pull the crankcase cover and that's it.Oil pump gear is in crankcase cover and pump may be also.

 

[beenthere]

Maybe needed to put in new rotor pump kit.

 

[Rob50056]

Maybe needed to put in new rotor pump kit.

Good picture and it looks very familiar.Isnt rotor metal?
I just replaced gear on oil pump and every part in oil pump is metal,unless I missed something.
How could the rotor wear out?
I only ask because after replacing cam,oil pump gear and other parts associated with upgrade to steel cam gear my oil light stays on and I may have to rebuild oil pump.
I tested my oil sending unit using compressed air and it seems to work.

 

[beenthere]

Rob
I do not know what the rotor material is, but gut feeling it is a hard rubber or neoprene.. and not metal.

Someone may chime in here who knows..

Being as it comes in a kit, then I'm thinking a normal wear item to replace.

Might be another way to test oil pressure.. to nail it down for you.

Checked in my service tech manual, and 40 psi is needed for oil pressure.. looks like the test port is where the oil sensor is threaded in by the oil filter can.

To continue, suggest you get the service tech manual. Might be an engine saver.

The oil pump inspection from service manual. The one Note that says the rotor housing should be filled with oil for initial lubrication suggests a possible cause of your lack of oil pressure.. just a thought.

 

[Coyote machine]

Here's some thoughts on why a rotor assembly might need replacement, and oil pressure could be lost. Age of tractor, number of hours on it. How often the oil and filter were changed and under what conditions engine was run. Was air filter service done regularly? Oil pumps and the rotor assemblies have close tolerances, as shown in the diagram. And if the mentioned screen was not fitting correctly or was excessively dirty or clogged this could contribute to loss of pressure.

You could switch to one of the high mileage oils used in older cars to take advantage of the 'molasses effect', which could help maintain better pressure once you rebuild whatever is worn out.

 

[beenthere]

I just read the other thread by Rob, and he found a spring missing.. assume all is fixed now.
http://www.tractorbynet.com/forums/john-deere-lawn-garden/381330-how-can-i-test-oil.html#post4795848