Farmall Cub

The Farmall Cub has been sitting in the garage. It has been a couple months since I last mowed with it. It started right up yesterday, but engine knocked due to lack of oil pressure and I shut it off as soon as I realized what the problem was. I guess the first thing need to do is remove the oil pan and check to see if the oil pump screen is clogged? Is there a shear pin on the oil pump? It was running fine when I parked it.

Prime the oil pump. Remove the oil filter cap. Inside the oil filter housing, front, down an inch or so is an opening. Put a cup of engine oil in the opening. Then crank engine over without starting engine until oil flows out of the opening.

I pulled the oil pan off. Screen is clear. I have been going to remove it anyway and check for sludge build up in the pan. No sludge in pan. I have been drivng Cubs "off and on" most of my life and never had this problem before. I will follow your recommendation. Thanks.

Check to see if the oil pump screws came loose and sucked part of the gasket inside and wont suck oil!---had 504 do that and the pump was fine with new gasket and really tighten the screws good! thanks; sonny

Eugene has you on the right track. The oil pump has lost its prime....I'll betcha!

Most common cause is the oil pump losing prime. No idea why it happens. I leave my Cubs sit for months during the winter and they always have oil pressure in the spring. Others can't leave them sit for a week.

As far as checking the oil pump for gasket issues, easier said than done. The oil pump is mounted high on the rear of the crankcase, and requires splitting the tractor, then pulling the clutch and flywheel.

Since you heard a knocking noise, I would recommend that you plastigauge the main and rod bearings while you have the pan off.

While you are at it, when the pan is off make sure that the tube coupling up on the engine block that is on the end of the pickup tube going into the pan screen is tight.

I will check the tube coupling for tightness, thanks. I was thinking that it could have vibrated loose.

bythepond88 wrote:Since you heard a knocking noise, I would recommend that you plastigauge the main and rod bearings while you have the pan off.

The knocking was caused by lack of lubrication. I just hope I didn't damage anything.

C. Amick wrote:The knocking was caused by lack of lubrication. I just hope I didn't damage anything.

Knocking from lack of lubrication. To late, damage done.

Check oil for grey metal bits.---bearing shell material. thanks; sonny