4020 oil pressure

I have a 1967 4020. It has a JD dealer rebuilt engine with 700 hours on it. it has always registered low oil pressure. I decided to buy an oil test gauge to determine if it was actually low pressure or a gauge issue. After connecting the oil pressure test gauge, started the engine and it registered at 30 PSI. I then operated the tractor for about 20 minutes to bring the engine to operating temperature and as the engine was warming up at 1900 RPMs, it gradually dropped from 30 PSI to 18 PSI - and would drop to about 10 psi at 500 idle RPMs. The shop manual says that at 1900 RPMs, the pressure should be at 30 PSI. If it isn't, the manual suggests adjusting the pressure valve/screw.

I tried to adjust the pressure by screwing both in and out the adjustment screw that sits just behind the oil fill cap on the right side of the tractor - pressure did not change at all - just remained the same whether screwing in or our.

Someone told me that the pressure drop might be coming from bad oil pipe O-rings - maybe even bad oil pipes.

So, I thought I would check to see if anyone might know specifically the issue. if this is it, I've got a little work ahead of me to replace the O-rings/tubes, but if not, I've got some more searching to do.

Any help would be appreciated.

Rick

There is a metal tube that goes onto the oil pump and which your engine oil filter sets. It is the housing in which the engine oil filter sets. Sometimes when installing it the large o-ring that goes on the oil pump gets damaged or rolled out of place. That is where I would start first.There other places to like worn cam bearing or if the front ventilator pump has been removed and it was not plugged correctly. Worn oil pump gears or a bad housing could also be an issue. Start with the filter housing. Tom

I'm with Tom,, that is most likely what the issue is...deal with it before you use it any more...

(quoted from post at 13:55:51 10/17/16) There is a metal tube that goes onto the oil pump and which your engine oil filter sets. It is the housing in which the engine oil filter sets. Sometimes when installing it the large o-ring that goes on the oil pump gets damaged or rolled out of place. That is where I would start first.There other places to like worn cam bearing or if the front ventilator pump has been removed and it was not plugged correctly. Worn oil pump gears or a bad housing could also be an issue. Start with the filter housing. Tom

Click to expand...

Thank you - very helpful. I'll start with the filter housing. I appreciate the input. Rick

I am jumping into the topic with questions about the ventialtor pump? My 5020 had one but it got removed. Should I check if they plugged it right
What was the purpose of it when the tractor was new?

The purpose was to pull crankcase fumes and put them back into the intake. We overhauled an engine once and for some reason the vent pump decided to fill the intake with oil. Needless to say the head gasket was history real fast and oil went everywhere. Found out latter the shop that cooked the block dropped it and broke our block and when they installed our parts into the replacement block they lost a check valve. I have not plugged one in 20 years or more but you need to plug the oil galley if you remove the gear. Tom