Farmall C oil pump observations

[Smarten_up]

So I mentioned earlier that my C had very low oil pressure. I took it out and found the bottom plate and gasket beyond repair.
At least 1/8 of warp in the plate, two directions of warp. New one is on order. But, I find a few things very weird.
First off the idler gear just floats on the plate, so in theory it could just wear the plate out?
Second the relief valve seems a joke, like how could the oil pressure ever get high enough for it to do any relief?
The oil passages are huge, no way that relief valve would ever relieve. My observations anyways.
Gonna get it fixed up shortly and see what kind of pressure I get. Luckily no significant damage done.

 

[SinkholeRoad]

(quoted from post at 16:27:17 08/18/22) So I mentioned earlier that my C had very low oil pressure. I took it out and found the bottom plate and gasket beyond repair.
At least 1/8 of warp in the plate, two directions of warp. New one is on order. But, I find a few things very weird.
First off the idler gear just floats on the plate, so in theory it could just wear the plate out?
Second the relief valve seems a joke, like how could the oil pressure ever get high enough for it to do any relief?
The oil passages are huge, no way that relief valve would ever relieve. My observations anyways.
Gonna get it fixed up shortly and see what kind of pressure I get. Luckily no significant damage done.

My observations are almost exactly the same as yours.
The aluminum pump covers always wore out.
The idler gear simply rests on the cover and wears.
It just doesn t seem like it would ever be able to over pressure.

Many of the pressure relief systems on working tractors are stuck and the owners just don t know because the systems never needs it.

My advice, flip the idler gear, put the new cover and gasket on, and run 15W40.
Good luck.

 

[Smarten_up]

I'll try it and see. The plate isn't actually worn from the idler gear yet, just warped, I guess bathed in oil there would be enough of a oil film under the gear so it could kinda float when spinning. Maybe the engineers already knew that in 1947?

 

[fastfarmall]

My Super C Engine got about 60 lbs of oil pressure now, with 30 weight low ash oil,but my plate wasn't that bad,I got two oil pressure gauge,[just a T, in the Line]45 lbs gauges, i can believe they have not busted off the needle's yet !!!

 

[Janicholson]

Others have made a steel reinforcement plate to go over the pump cover to keep it from failing. The clearance is supposed to be between .0005 and.001inch. The pickup tube may put enough force on the cover to cause the distortion as tractor bouncing and vibration wiggle the pickup. The gaskets are the adjustment for clearance. Jim

 

[Smarten_up]

I was thinking a steel plate could be made to work, not that hard to fab one up. But, I decided to buy one anyways.
I have the old plate and just might over winter decide to make one out of steel.
The oil pressure guage is original so it only shows a red mark at the lower end, maybe I'll put an actual guage that reads psi in there instead.

 

[Janicholson]

No matter how big the passages are they all lead to bearings. Proper fit at the bearings causes the pressure to open the relief valve. Imagine a 2 inch ID garden hose with a 1/4 inch opening. With the sil cock open, the pressure in the hose is totally related to the restriction of the nozzle, not the hose size. Jim

 

[Smarten_up]

I don't have a diagram of how the engine is lubricated.
That being said, everything in this engine appears to be 'splash lubricated' there are no oil lines leading to bearings.
The oil is pumped up to the rockers and just drips around the bearings and runs back down into the oil pan.
Pressure doesn't need to be very high if oil viscosity is low enough.
Even the oil pick-up strainer is kinda weird, what was the idea with it, to remove sticks, leaves and grasshoppers?
Its a simple engine I know, that's why I like it.

 

[riverbend]

The oil pump cover was very warped on my SC too. I flattened it out with various grades of sandpaper on piece of polished granite. There were still some of the wear marks in the cover when I was done. It works fine to this day.

As far as making a steel cover, isn't there something about two similar hardness materials running against each other wear faster ? Not to mention that the aluminum filings are soft. It seems like the edges of the gear teeth would cut into the aluminum but the body of the gear would wear the cover very slowly. Once the teeth aren't touching, they will cut very slowly too.

 

[Janicholson]

That engine is full pressure lubricated. The crank and rod bearings are fed from a gallery on the oil filter side. there are no cam bearing, the cam runs directly in the cast block. The oil filter is bypass type meaning it gets a metered stream of oil from the pump that goes through the filter and is dumped back into the pan through a hole. The center cam bearing has drillings in it that provide a squirt of oil through a drilling in the block to the center valve train bolt and disperses to the rockers and valves. they often hold 70psi of pressure in the gallery and hold 40 or more when warmed up and idling. The timing gears and cam drive are lubed by drip down from the front cam lobe. The governor main bearing shell is also pressure lubricated. Not as simple as it looks. Jim

 

[Smarten_up]

As I said I don't have a lubrication diagram for the engine. 70 psi seems a bit of a stretch but I don't know.
Probably work fine if I had even 10 psi oil pressure when still cold.
Just by looking at the relief valve, no way that plunger has moved in many years.
Maybe modern oil works better than what was available 75 years ago too?
I'm a gonna take a closer look, maybe put my glasses on this time.

 

[dhermesc]

Seems like a pretty sturdy build considering how old these tractors are.

I would imagine the bypass might come into play at 0 degrees with straight 30 weight nondetergent oil like it would have had when new.

 

[fastfarmall]

I believe you Jim, that they have 70 Lbs pressure,i got 50 lbs ideling,it's unreal, the needle is always pegged hot or bold!

 

[Rick Remmert]

My take on the aluminum cover is it is a sacrificial part. It is a lot cheaper to replace or polish the cover made of aluminum than one of steel. If it was made of steel, it would probably ruin the plate and both gears. If you had to replace the gears, you might as well buy a new pump. A lot cheaper to replace just the cover. No cost if you have the knowledge to straighten it on a surface plate.

 

[Smarten_up]

I of course looked at sanding the plate down to avoid paying for a new plate but, to get it flat too much material would need to be removed. Taking off over an 1/8 inch would serious weaken the plate. And yes I suppose its a sacrifical plate. Maybe intentionally, I don't know. My goal is to get some reasonable oil pressure again so as to not cause any severe damage to bearings/bushings etc.
I think a steel plate may work, haven't made one yet but if and when I get bored over winter I might just try it and see. The oil should protect it from the idler gear wear, wont know for sure until I try it. Thanks for all the replies everyone.
BTW, using heavy weight oil may not be the right thing for me, gets very cold here and sometimes I use the tractor in winter.