check oil pump while engine apart? (Feruson TO20)

I'm refreshing my TO20 Ferguson (new head, rings). Is there a way I can test the oil pump? Should I remove and disassemble and look for any problems?
I just got this tractor and am getting it running for the first time in 15-20 years. It has signs of overheating at some point (hence new head).
Since the pan is off, I'm just wondering what I should do to make sure the oil pump is pumping.

Yes, take it apart. No real need to test it if the clearances are within the bounds called for in the service book, and there is no obvious damage. Pack it full of grease when you put it back together , that will give it high vacuum for that initial start. Find your oil pressure regulator and take that apart and make sure it moves freely and the spring is not broken.

Do take the oil pump apart and check it for wear.

Gear backlash max .007.

Gear to pump body .003-.004.

Gear end clearance .004-.008 and check the cover for wear and flat. It can be surface ground to clean up.

Shim the drive gear to crank gear lash to .005-.010.

Look the set screws over closely that drive he shaft and driven gear. That is a weak point. Be sure the screws are tight, the gear is not split, or loose on the shaft.

Take the suction line and screen off and clean, clean, clean! Anything gets sucked into the pump will lock it and shear the set screw or split the gear!

While you are in there...

Be a good time to pull the cylinder liners and replace the orings, especially since it's been hot. If any liners rode up with the head off, they MUST be removed and resealed. Check the block for cracks between the cylinders at the bottom, common failure due to freezing. Clean thoroughly!!! Orings must seal, liners must bottom completely at the top flange. Liner height above block deck is CRITICAL,.001-.003.

Take a look at the governor. Early weighted style has been replaced with the ball type. Both are prone to fail, release pieces into the engine.

I have the oil pump off, and I'm trying to make sense of this.
The cover has what looks like a metal gasket that is in rough shape.
https://photos.app.goo.gl/Bots4XVwWrDfLuzb9

There is a lot of play between the teeth- I measure about .050 (50 thou). That seems excessive and more than would just be from wear. Can I somehow move the gears closer together?
https://photos.app.goo.gl/NHAzk7o9NRPPhfcx6

I couldn't get the img tag to display. Please click the links to see the pics.

I do have a manual 6x12 surface grinder with mag chuck. I've never really done any precision work on it, but maybe this is the occasion.

Thanks!

This post was edited by ironandsteel on 10/07/2022 at 10:52 am.

ironandsteel , It looks like the driven pump gear is way loose on the shaft ,from your pic.

I think maybe the gears are just really worn. Here is a closeup of the driven gear.

https://photos.app.goo.gl/8aPvGvtus8MhL3hF6

If I grab the gear that is driven by the crankshaft, I get a little bit of wiggle- but nowhere near enough to account for the big gap between the gears.

I think I need an oil pump rebuild kit.

But what about the plate- does that look like too much wear, and should there be a gasket there?