GP oil pressure

[olddeerefever]

I have a 1934 JD GP that I bought on a auction that appears to have been restored but I don't know to what extend it was gone thru. When I
start it the oil pressure peg comes up and seems all fine, but after its run a while or warmed up the indicator peg goes back down. I've never
run it very long that way but I'm puzzled as to what's going on, anyone have any ideas what could be going on?

 

[Sam Vastano]

Did you check the quality of the oil? Maybe there is fuel contamination and it is too thin? I would start with that first. If you are not sure change oil and filter and then check again. If it still does it then you are going to have to dig deeper to bearings etc.

 

[olddeerefever]

Yes that probably would be a good idea, hope it could be that simple. Thanks

 

[40JDG]

The oil pressure plunger should be able to be pushed down with your finger and it should leave a small indent on your finger like when you click a pen. If oil pressure is low there is an adjustment behind the flywheel on the pump housing. Take the cone shapped cap off the side of the pump and there will be a spring with shims inside. If you need more pressure ad a shim or two, if to much pressure take one out. Also i have found on a few GPs cracked oil lines inside the crankcase causing low pressure. Hope this helps

 

[olddeerefever]

Thanks I'll check that out also if need be.